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August 31, 2007

New tropical depression threatens islands

The National Hurricane Center has announced the formation of the sixth tropical depression of the 2007 Atlantic season. The storm is expected to become a named storm - Felix - on Saturday. Tropical storm warnings have been posted for St. Vincent and the Grenadines. Watches are up for the Dutch islands of Aruba, Bonaire and Curacao as well as parts of the Venezuelan coast.

This storm appears likely to follow a more southerly track across the Caribbean than Hurricane Dean. It appears unlikely to affect U.S. territory. Here's the advisory. Here's the predicted track. And here's a satellite view.

 

Posted by Frank Roylance at 5:01 PM | | Comments (0)
Categories: Hurricanes
        

August 30, 2007

"Still on track" for active hurricane season

So, here we are, in the statistical "peak" of the Atlantic hurricane season and what do we have to show for it? Just five named storms, including one hurricane. And, for now, the tropics seem surprisingly quiet.

It's not that we're wishing for more storms, mind you. It's just that forecasters have been insisting since April that we would see an unusually "active" season. All the conditions are there - warm sea surface temperatures, favorable winds aloft and the right La Nina conditions in the Pacific Ocean - to encourage storm formation in the Atlantic. Here is a map of current sea surface temperatures. Red and orange are warm, blue is cool.

 Current sea surface temperatures

And, somehow, it just seems like it's been unusually quiet.

Not at all, says Gerry Bell, of the NOAA Climate Prediction Center, whom I nabbed in the middle of his seaside vacation. "We're not changing the forecast," he said. "The conditions we predicted are still in place, and we're expecting an active season."

Active? With only five named storms? Granted, Hurricane Dean was one of the most intense Atlantic hurricanes ever at landfall when it went ashore last week on the Yucatan coast.

"There have been a lot of active years when we don't see a lot of activity until mid-August," Bell said. "Everything's in place for an active season."

The National Weather Service is still forecasting a total of 11 named storms this year. If they're right, we should have six more (including five that reach hurricane strength) to look forward to (or worry about) before the season ends officially on Dec. 1.

Both the weather service and Colorado State University experts have shaved back their earlier forecasts for the season by a storm or two. But both are still expecting the season to be more active than the long-term average. 

Colorado State's forecasters, Phil Klotzbach and William Gray, are expected to issue a new update to their forecast next week. We'll pass it along when it's published.

 

Posted by Frank Roylance at 2:45 PM | | Comments (1)
Categories: Hurricanes
        

Md. drought continues to ease

The latest Drought Monitor map from the US Department of Agriculture shows that the summer's drought has continued to ease in the past week. Here's the new map, out this morning. 

Although more than 90 percent of Maryland remains at least "abnormally dry," as measured by rainfall, stream flow, soil moisture and satellite measures of the health of vegetation, the proportion of the state's land area still experiencing drought conditions has fallen dramatically, from 78.8 percent a week ago to just 31.2 percent this week.

 University of Maryland

The regions still in moderate drought include Southern Maryland, from southern Prince George's and Calvert counties south to Charles and St. Mary's, as well as the southern portions of the Eastern Shore, roughly from Cambridge and the Choptank River south and east to the ocean and the Virginia line.

For the first time in many weeks, there are no signs of "severe" drought anywhere in Maryland, down from 7.4 percent last week and 55 percent the week before that.

The slow recovery comes too late, of course, for many Maryland farmers, who have lost much of their harvest for the year. As the graph above shows, drought is by far the most common cause of crop loss in Maryland. An agricultural drought disaster has been declared for the entire state. But suburban lawns, at least, have begun to green up again, and the summer buzz of lawn mowers has returned to the land.

Posted by Frank Roylance at 9:19 AM | | Comments (0)
Categories: Drought
        

August 29, 2007

Northwest Passage nearly open

USCG Icebreaker Polarstern 

It's been a dream of navigators since the 15th century - a regular sea route to the Orient without the long, arduous sail around the Cape of Good Hope or Cape Horn. For centuries, snow and ice blocked the Northwest Passage across the top of Canada. Indeed, it made it impossible to know whether it even existed. No one had sailed the route until a century ago, and the way was blocked by ice too much to make it practical.

Now, thanks to unprecedented summer melting of the Arctic sea ice, that sea route has nearly opened to blue water this month.

Here's a satellite view of the northern ice cap, showing the dark blue all-water path through the islands of northern Canada reaches nearly to the open water north of Alaska. The ice has also nearly melted clear of the entire Siberian coast.

Here's more on this summer's record meltdown on the Arctic Ocean. And there's still a few weeks to go before the Arctic Ocean begins to refreeze.

 

Posted by Frank Roylance at 1:32 PM | | Comments (2)
Categories: Climate change
        

Great weather for the long weekend

It would be hard to conjure up a better forecast for the long Labor Day weekend coming up. We'll have one more blast of near-90-degree heat on Thursday. But there's a slow-moving cold front headed our way from the north and west, and after a small threat of rain late Thursday and Friday,  as the front slides through, we're golden for the weekend.

Look for a high of barely 80 degrees on Saturday, with drier air and lots of sunshine as high pressure builds into the region behind the front. Sunday and Monday will be even sunnier, but only a bit warmer, with highs rising only to the mid-80s. 

This week could be our final flirtation with the 90s this summer. Average daily high temperatures in September slip from the low 80s into the 70s. Ninety-degree weather isn't unheard of. But those occasions approach record territory in September. By month's end, the record highs are in the low 90s.

Headed for the beach this weekend? Here's the forecast. Don't forget the sunblock. You still need it.

 

 

Posted by Frank Roylance at 10:27 AM | | Comments (0)
Categories: Forecasts
        

August 28, 2007

Eclipse greets early commuters

Photo by Michel Hersen - Portland, Ore.

Skies remained clear enough just before dawn to show off the start of this morning's total eclipse of the moon. I hauled myself out of the sack at 5 a.m., threw on some clothes and drove to a nearby parking lot with a good view to the west.

As early commuter traffic began trickling down the state road to my south, I watched for about a half hour as the full August "Fruit Moon" drifted into the darkest part of the Earth's shadow. It was the moon's upper edge that dipped into the "umbra" first. With the urban light pollution and slowly brightening skies, the expanding shadowed portion of the otherwise brilliant full moon became all but invisible to the naked eye. 

Through binoculars, however, it had that dull, reddish hue that makes lunar eclipses so eerie. Somehow, that ochre light - the reflected light from all the sunsets and sunrises underway on the Earth - always gives the moon a distinctly spherical appearance that you don't see with a normally illuminated moon. The "regular" moon looks like a flat disk - a big, silvery tiddlywink.

But this eclipsed moon looked like the big ball that it is. And, as I watched, the shadowed portion spread across what remained of the sunlit slice. Here's how others saw it.

As I stood there in the dark, with my 10x50 binocs and drive-time radio in my earbuds, somebody pulled into the parking lot in a huge SUV. He drove around for a minute, then settled in behind me, his engine running. I assumed he was watching the eclipse, like me. After a few minutes, he got out of the truck, stood beside the driver's door and snapped a flash picture. A flash picture? Did he think his point-and-shoot would light up the moon? I chuckled, and he drove off to resume his pre-dawn commute.

By 5:35 or so - still 20 minutes before the period of totality began, all that remained of the moon that was visible to the naked eye was the sliver of a lunar "smile" - the only bit that was still in direct sunlight. And then the smear of clouds along the horizon swallowed the moon, and the show was over.

Read more about it here.

The next total lunar eclipse is on Feb. 20, 2008. If the weather cooperates, it will be visible here, from start to finish, at a much more convenient (evening) hour.

Posted by Frank Roylance at 9:55 AM | | Comments (2)
Categories: Sky Watching
        

August 27, 2007

A snowy day in 2005 ... or was it?

A private school teacher has been acquitted of the most serious charges against him in a set of sexual assault cases brought prosecutors on behalf of three of his former students. One of the young girls accused him of raping her as he drove her home from school in his car on "one snowy day" in February 2005. Here's The Sun's story of the acquittal.

The alleged crime took place on Feb. 23, according to prosecutors. But the teacher's attorney, seeking to undermine the girl's credibility,  argued during his closing that on Feb. 23, 2005 "it simply was not snowing" in Baltimore. And he was right. There was no snow that day. It never got cold enough to snow.

But the next day? Temperatures on Thursday, Feb. 24, 2005 dropped into the 20s and it snowed quite a bit, with more than 5 inches accumulating at BWI. In fact, it snowed nearly all day, the snowiest day of that entire winter. Was the girl's story bogus? Or was she simply confused about the date?

Sun reporter Julie Bykowicz, who covered the trial, says, "School was closed on the 24th and 25th, so everyone (police, defense attorneys, etc) determined the only possible date this could have happened was the 23rd. 

 

Posted by Frank Roylance at 9:27 PM | | Comments (0)
Categories: History
        

Lunar eclipse early tomorrow ... Will we see it?

With high pressure and drier air moving into our region today, there is a reasonable chance we'll see tomorrow's pre-dawn lunar eclipse. On the other hand, forecasters expect a wind shift tonight. Easterly winds off the ocean will eventually bring higher humidities, and that would create murkier viewing by dawn. But the betting in Sterling this morning was that humidity will hold off, and skies will remain "mostly clear overnight."

Lunar eclipseThat said, this eclipse - the second full lunar eclipse of the year for Maryland - was never destined to be a memorable one. Here's why:

The full August "Fruit Moon" is set to slip into the darkest part of the conical shadow the Earth casts into space - the "umbra" - at 4:51 a.m. Tuesday morning. Observers with a clear view toward the west will notice the upper left edge of the full moon's disk becoming noticeably dimmer.

Here's a cool animation of what you'll see. Cloudy skies? Too lazy to go outside and watch? You can find live coverage, online, by clicking here.

The moon will continue to plunge into the shadow for about an hour. By 5:52 a.m., it will be in full eclipse. Provided clouds, humidity or air pollution near the western horizon don't obscure it entirely, it may appear to have a dull red or coppery color. For an astronaut standing on the moon looking back, the dark, night side of the Earth would appear to be eclipsing the sun, surrounded by a reddish ring of light - the combined glow of all the planet's sunrises and sunsets. It's that light, scattered by the clouds and atmospheric dust, that paints the reddish color across the moon's surface as seen from Earth's night side.

NASA scientists will be using the period of totality to scan the moon's darkened surface for flashes of light caused by the impacts of meteors. You can read more about that here.

Unfortunately, our view of totality will be a fleeting one at best. Sunrise in Baltimore tomrrow will occur at 6:31 a.m. EDT, just a bit more than a half hour after totality begins. And the moon itself is scheduled to set below the western horizon just a few minutes later, at 6:34 a.m. 

So, the sky will be brightening throughout the short time we have to observe totality, washing out our view. And the moon will be sinking deeper into the murky skies close to the horizon, further dimming the scene.

For a better view, hop a plane today and head west. The entire eclipse will be visible from the West Coast. Totality will start there at 2:52 a.m. Pacific Daylight Time, and end at 4:23 a.m. PDT, with the partial phase winding up at 5:24 a.m. PDT. 

Our next opportunity to see a full lunar eclipse, from start to finish (provided skies are clear, and it's not snowing), will come on the evening of Feb. 20, 2008.   

Posted by Frank Roylance at 10:36 AM | | Comments (0)
Categories: Sky Watching
        

Greece on fire

Deadly wildfires have killed dozens of people in the southern Peloponnesus region of Greece in recent days. Greek authorities suspect arson on many of the fires. Here's more from CNN, and the BBC. And here is a remarkable satellite image of the fires and smoke.
Posted by Frank Roylance at 9:35 AM | | Comments (0)
Categories: Events
        

August 25, 2007

Fireball sighted over Baltimore

Emily Johnston sent us this report overnight: "At exactly 9:54 this (Friday) evening I was sitting outside and saw this HUGE green fireball streak across the sky, SE to NW. This totally blew me away. What do you suppose it was?"

Emily: It was a huge green fireball ... a meteor, either metallic or stony. Friction with the atmosphere as it streaks in heats the air molecules, stripping them of electrons. As they cool and regain the electrons, they give off light. The green color is characteristic of oxygen. The meteors themselves usually vaporize during their fall, and only rarely reach the ground. 

Lots of them fall every day, but most aren't observed because it's daylight, or because most fall over the ocean or other uninhabited places. But anyone who sits outside at night under clear skies will eventually see some.

There's a neat video of an entering fireball on this page.

You can read more about fireballs here. Readers: Did anyone else see this one? Leave a comment and describe where you were and what you saw. Thanks.

Also, the American Meteor Society wants people to report any fireballs they see. Here's the report form.

 

Posted by Frank Roylance at 7:15 AM | | Comments (0)
Categories: Sky Watching
        

August 24, 2007

What's wrong with this forecast?

Lots of MarylandWeather.com readers are getting a chuckle out of this prognostication today. Can you find what's got them laughing?   View image

Posted by Frank Roylance at 4:44 PM | | Comments (2)
Categories: By the numbers
        

Rains ease MD drought

Recent rains across Maryland have eased the worst of the drought that has been spreading and deepening all summer. But more than 92 percent of state remains under unusually dry to severe drought conditions, only slightly improved from last week (96 percent).

Data from the USDA's weekly Drought Monitor map shows the portion of Maryland that's enjoying normal, rains, streamflows and soil moisture is in Garrett County. It constitutes just 7.5 percent of the state, but that's an improvement from the 4 percent in that category last week.

The portion of Maryland that's in moderate to severe drought still amounts to 78.8 percent of the state, up slightly from last week (78.2 percent).

But that portion of the drought-stricken region where conditions are rated "severe" has fallen dramatically in the past week - from 55.7 percent to just 7.4 percent of the entire state. Most of that territory is in Charles and St. Mary's counties. Severe drought conditions have eased to moderate for much of the state, from Washington County eastward to the lower Eastern Shore. Since Sunday, BWI has recorded 1.69 inches of rain. Some locations saw more than 2 inches.

The USDA uses data from rainfall, streamflow, soil moisture and satellite-based reckoning of vegetation damage to calculate the drought index, and construct the weekly maps.

While conditions may have improved with the recent rains, it's too late for many of Maryland's farmers. A federal drought disaster has been declared for the entire state, making low-interest loans and other assistance available to many farmers. Read more here.

Posted by Frank Roylance at 3:21 PM | | Comments (0)
Categories: Drought
        

Summer returns with a vengeance

Kinda felt like autumn for a few days there, didn't it? Well, that's over. The National Weather Service has issued an Excessive Heat Watch tomorrow in Baltimore and Washington. With the sun coming back out after a long absence, daytime temperatures could top 100 degrees on Saturday. Given the expected high humidities, with breezes off the Chesapeake, the Heat Index readings tomorrow could exceed 110 degrees.

UPDATE: 3:30 p.m.: The National Weather Service has issued a Heat Advisory for 11 a.m. to 8 p.m. Saturday for all of Maryland between Frederick County and the Chesapeake Bay, and for the northern portion of the Eastern Shore. Here's more.

Forecasters were calling for a high of 104 degrees in downtown Baltimore. They seem to have backed off a bit from that. Here's the downtown forecast.  A high of 104 would be the second-highest temperature of the summer for the city. The hottest was 106 degrees, reached at the Maryland Science Center on Aug. 8. (It was "only" 102 degrees that day at BWI.)

The forecast for the airport calls for a high of 98 degrees. Even that would beat the 97-degree record for the date, set in 1968. (The average high for an Aug. 25 at BWI is 84 degrees. The coolest high was 65 degrees, set in 1940.

The satellite view shows the stubborn cloud cover lingering over much of Maryland. It's beginning to break up. But continues to shield us from the still-strong August sun. And that's been keeping temperatures well below average for this time of year.

But where the clouds scatter, and the frontal system and "cold air damming" east of the mountains that caused it, begin to depart, temperatures will rise. We'll be rid of this marine air, and get back into a flow of warm, humid air from the south and southeast, and we'll cook.

All the big rain, meanwhile, will stay to our north and west. We may get a shower or two, and some could drop a couple of inches locally, but none of the flooding rains we're seeing on TV from Ohio and Minnesota, or the ferocious thunderstorms they got in Chicago.

By Monday, as Baltimore school kids head back to class, we should be looking at highs in the mid-80s.

 

Posted by Frank Roylance at 12:10 PM | | Comments (0)
Categories: Forecasts
        

August 23, 2007

Wednesday's high tied record

When the official thermometer at BWI-Marshall reached its measly afternoon high of 69 degrees on Wednesday, it tied a record. It wasn't a record high, of course. That would have required topping out at 99 degrees - the record high for the date set in 1983.

The day's high of 69 degrees tied the record low maximum temperature for an Aug. 22, set in 1990. That means the highest temperature of the day was as cool as it's ever been on an Aug. 22 in Baltimore since record-keeping began in 1871.

The average temperature for the day was a mere 65 degrees (high 69, low 61), which is 9 degrees below normal for the date. It was the coolest day, relative to long-term daily averages, since April 16.

Wednesday was also the fifth straight day of below-normal daily average temperature. It's a far cry from just two weeks ago, on Aug. 8, when we topped out at 102 degrees at BWI, with an overnight low of 80 degrees. That made the day's average 91 degrees, 15 degrees above normal for an Aug. 8 in Baltimore.

By Saturday, of course, it will all be forgotten. They're predicting an afternoon high of 99 degrees at the airport that day as this stubborn, gray frontal system finally blows away to the north and we get back into a real mid-summer flow of hot, humid air again. After some showers later in the weekend, and a new air mass, things will cool a bit, and get back into the more seasonable 80s.

Posted by Frank Roylance at 11:46 AM | | Comments (1)
Categories: By the numbers
        

Lake Superior nears record low water; warm winters a factor

 Lake Superior - NASA

The water level in Lake Superior has been slipping for years, and is now nearing record lows, according to the National Oceanic and Atmospheric Administration. Monitors put the current lake level at 183.028 meters, close to the record low for August of 182.97 meters.

The all-time record low water measurement for Superior - the largest of the Great Lakes - is 182.69 meters, set in April 1926. The record low water for September and October is 183.06 meters, NOAA says, so there is some possibility a new record low could be set this fall.

There are a variety of possible explanations for the falling water levels. The region has been experiencing unusually warm winters in recent years. Higher temperatures and reduced ice cover in winter causes greater rates of evaporation from the lake. And reduced snow cover has meant less runoff into the lake.

Some observers are also blaming years of drought and human factors, including water diversion and dredging, which has increased drainage from the lake. 

The drop in water levels has reduced shipping on the lake as carriers try to lighten their loads to avoid running aground. Marinas are also having to dredge or close as lake levels fall.

You can read more about it here.

Posted by Frank Roylance at 11:20 AM | | Comments (0)
Categories: Climate change
        

August 22, 2007

The drip goes on ...

Looks like more drips and drizzle in the forecast today as we remain stuck beneath this stalled frontal boundary. After an inch-and-two-thirds of rain over the past three days, we're expected to get more clouds and drizzle today, with occasional showers this afternoon and tonight as well. We can hardly complain, after a long summer with hardly any sustained precipitation, and news of awful flooding coming in from the Midwest.

Accumulated rainfall so far this month comes to almost 2.5 inches. That's close to the average for the first three weeks of August.

The cool temperatures are something else. Yesterday's high at BWI was only 68 degrees. That's 16 degrees below the average high temperature for BWI on an Aug. 21, and the coolest high temperature since May 18, when it was just 63 degrees.

But it wasn't close to the record "low maximum" for the date. That was 63 degrees, set on Aug. 21, 1926. A 68-degree maximum today would have beaten the record, however, besting the 69-degree high reached on this date in 1990. But today's temperatures should rise above that, into the low 70s. That's still cool. The average high for an Aug. 22 in Baltimore is 84 degrees.

But we haven't seen the last of the summer-like temperatures. Not by a longshot. The sun should creep back into sight by Friday, with highs in the low 80s. And we'll be back in the 90s for the weekend, as the stalled front drifts back to our north, bringing us back into the warm, muggy southern flow. Look for high heat indexes again until another cool front washes it all away for the first week of school for many local kids. Here's the discussion from Sterling.

 

Posted by Frank Roylance at 8:24 AM | | Comments (0)
Categories: Forecasts
        

August 21, 2007

Dean was 3rd most intense ever at landfall

Dean at landfall - NOAA

Hurricane Dean had a central barometric pressure of 26.75 inches just before making landfall near the Mexico-Belize border early today. That made it the third-most-intense Atlantic hurricane at landfall since record-keeping began in the 1850s, according to the National Hurricane Center.

The air pressure in the eye of a hurricane is an indicator of a storm's ferocity because it's the low central pressure that powers the winds swirling around the eye, and the storm surge. 

The only storms with lower barometric readings at landfall were the unnamed 1935 Labor Day storm that ravaged the Florida Keys, with a pressure of 26.35 inches; and Hurricane Gilbert, which struck Mexico's Yucatan peninsula in 1988 with a central pressure of 26.22 inches.

The lowest barometric pressure ever recorded in an Atlantic hurricane was 26.05 inches, for Hurricane Wilma while at sea in 2005.

If Dean had made landfall in the United States, it would have ranked as the second-most intense ever to come ashore in the U.S., after the Labor Day storm in 1935. The next-most intense at landfall in the U.S. was Hurricane Camille, a deadly Category 5 storm that tore up the Gulf Coast of Louisiana and Mississippi in 1969. Its pressure at landfall was 26.84 inches.  

In the meantime, a weakened but still deadly Dean continues its trek across the Yucatan. Hurricane warnings are going up along the Mexican Gulf Coast. Here's the latest advisory. Here's the predicted storm track, and here's the satellite view.

 

Posted by Frank Roylance at 11:11 AM | | Comments (0)
Categories: Hurricane background
        

Storms triple BWI's August rainfall

It's catch-up time at BWI-Marshall. The rain storms that began tracking through the area on Sunday have tripled the official rainfall for the month of August, bringing us close to normal for an August in Baltimore.

By the end of the day on Saturday, the NWS instruments at BWI had recorded just 0.77 inch of precipitation for the month. Since the rain began on Sunday, another 1.66 inches have fallen, bringing the tally to 2.43 inches. The average August rainfall for Baltimore is 3.74 inches, but we have 10 days to go.

The recent rains have not erased the water deficits accumulated since May 1, which still amount to more than 4.5 inches.

Baltimore seems to be leading the region in rainfall from these storms. Here are some measurements from around the region, beginning Sunday and running through early this morning:

BWI: 2.43 inches

Baltimore Sun:  1.22 inches

Maryland Science Center:  1.47 inches

WeatherDeck (Cockeysville):  1.08 inches

Frederick:  1.68 inches

Ocean City:  2.13 inches

Washington, DC:  2.03 inches

Dulles Int'l:  1.04 inches

Here are some more readings from around the Baltimore area. Click here. And here is a look at how area streams have responded. Those marked with black dots are flowing at record highs for the date.

And here is the storm's total rainfall loop.

 

Posted by Frank Roylance at 10:33 AM | | Comments (0)
Categories: By the numbers
        

August 20, 2007

"Holy smokes! That's impressive..."

Dean's eye - NASA

Astronauts aboard the International Space Station got a first-hand look at Hurricane Dean as they flew over the strengthening storm yesterday. As the station passed 200 miles above the storm's eye, one of the spacemen said, "Holy Smokes! That's impressive." You can see it as they did on a NASA video. Click here, then look for the video link on the right-hand side of the page.

Dean is roaring westward across the Caribbean toward a catastrophic landfall early tomorrow on Mexico's Yucatan peninsula and the tiny country of Belize, the former British Honduras. Top sustained winds at the storm's center are raging now at 150 mph, and some further strengthening is expected before landfall.

Forecasters are warning that Dean is likely to become a Category 5 storm, with top sustained winds of more than 155 mph, before making landfall. That wind will be devastating to the region. It will drive a storm surge onto the coast north of the center - where the resort cities of Cozumel and Cancun are located - 12 to 18 feet above normal tides. People in the storm's path who escape the rising water will be dealing with rains of 5 to 10 inches, perhaps as much as 20 inches in some locations. That will cause flash flooding and mudslides.

Belize is located south of the center of the storm's path. That should mean slightly reduced wind speeds and storm surges. 

Here's the latest advisory. Here's the forecast storm track. And here's a satellite view, showing Dean's buzz saw spinning across the western Caribbean at the left of the image.

Posted by Frank Roylance at 2:52 PM | | Comments (0)
Categories: Hurricanes
        

Raindrops on dead grass

Northern counties in the Baltimore region could see up to a half-inch of rain later today as weak lows begin to traipse through the area along a stalled frontal system. Southern counties will see Clouds over Maryland Sunday

less. And as the front drifts slowly north this week, we will begin to feel the return flow from the high to our south and east. That air will be hot and humid. Enjoy the 70s now, because we're headed back into the 90s by the end of the week.

Here's the forecast. If it proves accurate, we could pick up as much as an inch of rain from this set-up before it moves off. Some of it includes remnants of tropical storm Erin, now caught up in continental weather systems. It may be wet and gray, but it's good weather news nonetheless. Here is the Drought Monitor map from last Thursday, in case anyone needs reminding. Streamflow in some parts of the state is still quite low.

Not so to our north and west. Minnesota flooding from persistent heavy rains has killed at least four people. Read more about it here. There's been too much rain in South China, too, where Typhoon Sepat has exacted a terrible toll.

Posted by Frank Roylance at 10:58 AM | | Comments (0)
Categories: Forecasts
        

August 19, 2007

Barometer falling as Dean intensifies

The latest advisory from the National Hurricane Center indicates that the storm's central pressure has dropped to 27.34 inches. That's evidence of the storm's intensification, and a warning that higher winds can be expected. Dean is already a Cat. 4 storm with top sustained winds of 145 mph. Some gusts have topped 180 mph.

Dean, while it is forecast to grow stronger, does not seem likely to strike U.S. territory at full force. Its forecast track carries it over Mexico's Yucatan peninsula. That will be a catastrophe for residents there. But that initial landfall will weaken it considerably before it moves back over the Gulf and heads for a second landfall on the Gulf coast of the U.S. or Mexico.  

How low can a hurricane's central pressure fall?  Here is a quick and sobering rundown of some of the most intense storms ever recorded, from Geocities.

"Since 1900 the most intense hurricanes to strike the Gulf coast had barometric pressure readings in the 27.49 to 27.91 inch range (931 - 945-mb). Hurricane Camille (1969) is separated from this group due to its extreme intensity.

"Worldwide - landfalling tropical cyclones with a barometric pressure of less than 28.00 inches (949 mb) are rare. Of the forty major hurricanes to cross the Gulf coast since 1900 - only nineteen made landfall with a pressure below 28.00 inches.

"Recent historical research has uncovered evidence that the Great Hurricane of 1919 may have had a landfalling pressure below 28.00 inches in Texas. The 26.84 inch (909Mb) barometric pressure reading taken in Bay St. Louis, Mississippi during Hurricane Camille - is the lowest sea level pressure ever measured in a landfalling hurricane along the Gulf coast. Only during the 1935 Florida Keys hurricane was a lower barometric pressure recorded (26.35 inches/892 Mb).

"Over the open sea - a few hurricanes, and supertyphoons in the Western Pacific, have had barometeric pressures measured below 900 mb (26.60 inches) In 2005, a new record low barometric pressure was measured in Hurricane Wilma - 26.06 inches (882 mb), in the very active 2005 hurricane season.

"The World record is 25.90 inches (870 mb) in Supertyphoon Tip in 1979. Sustained winds in these super tropical cyclones have been measured at speeds approaching 200-mph. However, only since the late 1940's have scientists had the ability to accurately make these measurements."

For a list of the most intense storms, from the NWS, click here and scroll down to Page 10.

Posted by Frank Roylance at 12:46 PM | | Comments (1)
Categories: Hurricanes
        

Hope for lawns, wet for the beach

A stalled weather front has brought us the cool temperatures that were forecast for the weekend. Cooler, even, than the original forecasts, with highs only in the low 70s today. But the sunshine and dry weather seem to have vanished from the predictions.

Light rain or sprinkles are dampening the dust today, and the forecast calls for more of the same, plus the possibility of some thunderstorms as the week rolls out. That's great for the dry, brittle lawns across the region, though maybe too late for farmers to salvage much. It's also going to disappoint families who picked this week to visit the beach - the last week before schools open in some counties.

But the predicted rain - some of which, later this week, could be described as the remnants of Tropical Storm Erin - will put the brakes on the deepening drought in Maryland, if not begin to ease it. It's not likely to end it, but it may mark the beginning of the turnaround.

Here's a radar image showing the arc of rain across the eastern U.S. that will be filtering through here this week. That rainy patch over Oklahoma is the remnant rain from Erin. Here's a closer look.

Here's a bit of today's forecast discussion from Sterling:

"MONDAY NIGHT THROUGH WEDNESDAY

"A WAVY FRONT WILL REMAIN ACROSS THE MID ATLANTIC THROUGH TUESDAY
NIGHT. SEVERAL WEAK WAVES APPEAR TO TRACK ALONG THE FRONT...BRINGING
THE BEST RAINFALL CHANCES THE REGION HAS SEEN FOR QUITE SOME TIME.
PRECIPITABLE WATER VALUES RISE TO NEAR 2 INCHES...WELL ABOVE THE
NORMAL OF 1.1 INCHES. PRECIPITATION CHANCES WILL COME WITH
HARD-TO-TIME WEAK WAVES MOVING ALONG THE FRONTAL BOUNDARY. GUIDANCE
STILL SHOWS THAT THE NORTHERN HALF OF THE FORECAST AREA HAS THE BEST
CHANCE OF SEEING NOTICEABLE PRECIPITATION WHILE THE SOUTHERN HALF OF
THE FORECAST AREA COULD BE LEFT HIGH AND DRY. OVERALL...INCOMING
CLOUD COVER ASSOCIATED WITH THE FRONT WILL SPREAD NORTH AND SOUTH
RATHER FAR...AND THIS SHOULD HELP TO KEEP TEMPERATURES WELL BELOW
NORMAL.

"THURSDAY THROUGH SATURDAY...

"HIGH PRESSURE WILL BUILD ONCE THE FRONT HAS EXITED THE
REGION...BRINGING A RETURN TO A MORE TYPICAL WARM AND HUMID AIRMASS."

We've had three whole hundredths of an inch so far here on the WeatherDeck in Cockeysville. Practically a monsoon.

 

Posted by Frank Roylance at 12:17 PM | | Comments (0)
Categories: Forecasts
        

August 17, 2007

Arctic ice melt surpasses record

The National Snow and Ice Data Center (didn't know we had one, did you?) is reporting that the arctic ice cap at the top of the planet has shrunk to a record minimum. And the ice cap melting season isn't over yet.

The solid ice in the Arctic Ocean melts back ever summer, but the extent of that annual melt has been growing dramatically larger in recent years, exposing more open ocean. That is reducing the amount of solar energy that's reflected back into space by the ice and snow, accelerating the warmup of the sea, contributing to global warming and eroding the habitat of arctic creatures such as walruses and polar bears.

The past record meltdown of the polar ice was reached in 2005. It left just 2.05 million square miles of ice. Already this summer, the ice has retreated farther than ever before recorded, leaving 2.02 million square miles of ice. And the date of maximum meltdown is usually reached in mid-September. So we have another month of melting to go.

You can read more about it here.

Posted by Frank Roylance at 4:13 PM | | Comments (0)
Categories: By the numbers
        

Space Station week for Maryland

They won't be the most ideal passes we could hope for, but - if skies are clear - the coming week will offer Marylanders at least four good opportunities to watch the International Space Station fly over just as the Shuttle Endeavour and its astronauts prepare to leave the station and return to Earth.

Here are the times and other specifics for these passes.Allow yourself a minute or two of leeway on these flyovers in case the prediction times slip between now and the event. Also, pay attention to news of the shuttle's departure from the ISS, and planned Aug. 22 landing. And be prepared to watch for two objects flying in close formation - the ISS and Endeavour.

Sunday, Aug. 19: Look for the ISS to appear above our northwest horizon at 9:06 p.m. as it passes over the Great Lakes. It will pass the bowl of the Big Dipper, and Polaris (the "North Star"), rising as high as 50 degrees over the northeast horizon at 9:09 p.m. as it flies directly over New York City. Then, at 9:10 p.m. it will disappear abruptly as it flies into the shadow cast into space by the Earth (night).

Monday, Aug. 20: The ISS will rise above our northwest horizon at 9:29 p.m. just as it passes over Chicago. Headed southeast, it will rise as high as 42 degrees (halfway up the sky) above the southwest horizon before at 9:31, disappearing into the Earth's shadow at 9:32 p.m.

Tuesday, Aug. 21: The ISS will appear above the northwest horizon at 8:16 p.m., rising to 48 degrees above the northeast horizon at 8:19 p.m. This time, the station will be visible all the way to the eastern horizon, where it will slip from view at about 8:22 p.m.

Wednesday, Aug. 22: Rising again in the northwest, at 8:39 p.m., the space station will soar from Chicago toward the North Carolina Capes. It will rise as high as 44 degrees above our southwest horizon at 8:41 before zipping off toward the southeast, disappearing into the Earth's shadow at 8:44 p.m.

Posted by Frank Roylance at 12:36 PM | | Comments (0)
Categories: Sky Watching
        

Dean pummels islands, now a Cat. 3

Hurricane Dean has crossed the arc of islands in the Lesser Antilles, pounding the French island of Martinique, as well as Dominica and St. Lucia. Top sustained winds remain at about 100 mph, making Dean a Category 2 storm on the Saffir-Simpson scale of hurricane intensity.

UPDATE: 3 p.m. Dean has strengthened today to a Category 3 storm, with top sustained winds over 125 mph.

Jamaica and the Cayman Islands will be the next to feel Dean's power.

Forecasters expect little change in Dean's strength or direction for the next 24 hours or so. Light wind shear is keeping a lid on the storm for now, and it has been struggling to develop a well-organized eye and wind structure. But beyond the next day or so, conditions are expected to improve for this storm. It is still predicted to strengthen to Category 4, with top sustained winds of at least 131 mph.

The other issue for forecasters is figuring out where Dean will go. For now, he is cruising briskly westward. But looking farther ahead, forecasters expect he will begin a gradual turn to the northwest. Depending on the timing and angle of that turn, Dean will either run ashore on Mexico's Yucatan peninsula and weaken, or turn northwest through the Yucatan Channel and enter the Gulf of Mexico. Warm waters in the Gulf can be expected to add dangerous fuel to the storm if it gets organized. The consequences for Texas and Louisiana can only be imagined.

Here is the latest advisory on Dean. Here is the predicted storm track. And here is a satellite view.

Here's an earlier story about Dean and Erin, which is now a huge rainstorm causing more severe flooding in Texas. 

Posted by Frank Roylance at 10:28 AM | | Comments (0)
Categories: Hurricanes
        

August 16, 2007

Dean targets St. Lucia, Dominica

Hurricane warnings are up for the Caribbean islands of St. Lucia and Dominica as Hurricane Dean continues to strenghthen. The storm, packing top sustained winds of nearly 90 mph, is still 400 miles east of the islands, barreling westward at 24 mph.  

Here's the latest advisory. Here's the predicted storm track, which has it striking the islands tonight, with 2 to 5 inches of rain and a storm surge of 2 to 4 feet. And here's a satellite view.

This storm is expected to continue strengthening, becoming a Cat. 3 "major" hurricane in the eastern Caribbean. It could eventually become a threat to the Yucatan, and the Gulf of Mexico, where waters are warmer still - fuel for further storm intensification.

Meanwhile, Tropical storm Erin has gone ashore in South Texas, and has now been downgraded to a tropical depression. It is little more than a really bad rainstorm, potentially 3 to 6 inches of rain in some places, with isolated accumulations of 10 inches. Here's the last advisory from the hurricane center on Erin.

Posted by Frank Roylance at 10:49 AM | | Comments (0)
Categories: Hurricanes
        

MD drought slightly worse

The USDA's new Drought Monitor map for this week is out. It shows that the extent of Maryland's geography affected by moderate to severe drought has increased a bit sinc elast week, despite some teaser rain showers. Only northwestern Garrett County has returned to normal conditions since last week. Here's the map.

Just over 78 percent of Maryland is now experiencing moderate to severe drought conditions, as measured by streamflow, rainfall, soil moisture and satellite-based measurements of damage to vegetation. That is up from 75 percent during the last two weeks.

The portion of the state in severe drought has increased from 50 percent to just over 55 percent.

About 18 percent of the state, including Baltimore, is considered to be merely "abnormally dry." The corner of Garrett County that has returned to normal moisture levels constitutes just 4 percent of the state.

 

Posted by Frank Roylance at 10:36 AM | | Comments (1)
Categories: Drought
        

Peru quake shakes Va. well

Christianburg, Va. well response

Last night's 8.0 earthquake southeast of Lima, Peru, sent the water level in the USGS groundwater monitoring well near Christianburg, Va. surging. A second, slightly less sensitive well in Augusta County also felt the tremor from 3,400 miles away. Hydrologist David Nelms writes:

"The water level started oscillating about 15 minutes after the quake.  The total oscillation was 0.50 feet and lasted for nearly 3 hours.  The long period of oscillation is mainly due to the magnitude and close proximity of the M7.9 and the numerous M5+ aftershocks.

"The Augusta County well also saw a response.  Again the water level started oscillating about 15 minutes after the quake.  The response in this well is normally more subdued as evidenced by the smaller oscillation of 0.09 feet and shorter period of just over 30 minutes." 

Here's the tracing from the Christianburg well. Here's another view of the well's response. And here's the USGS report on the Peru quake. At this writing, the USGS has reported 14 aftershocks since the initial quake last night. Two of them have been 6.0 quakes or stronger.

Posted by Frank Roylance at 10:00 AM | | Comments (0)
Categories: Events
        

August 15, 2007

Tropical update: Flossie, Dean and Erin

NASA

All of a sudden we have three tropical storms active, all with the potential to affect U.S. territory. Here's the morning line:

TS FLOSSIE:  A 140 mph, Category 4 storm as recently as Saturday, Flossie has been weakening as it approached the Hawaiian Islands. It is now a tropical storm, sending wind, water and waves onto the islands, but skirting westward well south of the 50th state and apparently no longer a serious threat. Here's the latest advisory. Here's a satellite view. And here's the predicted storm track. And, here's what the newspapers are saying.

TS DEAN: The fourth named storm of the 2007 Atlantic season, Dean is steaming westward across the tropical Atlantic, headed for the Lesser Antilles, and the Caribbean, with some slim risk of a strike in the U.S. Virgin Islands and Puerto Rico. It is still 1,000 miles east of the islands, but it is slowly strengthening, with top sustained winds for the moment at about 60 mph. At 74 mph it would become the season's first full-fledged hurricane. Here is a bit of this morning's tropical discussion from the National Hurricane Center:

"AS DEAN CONTINUES TO APPROACH THE LESSER ANTILLES IT WILL BEGIN TO
ENCOUNTER WARMER WATER AND LESS WIND SHEAR AND WILL LIKELY
BECOME A HURRICANE AS IT NEARS THE ISLANDS."

Here is the latest advisory. Here is the predicted storm track. And here is a satellite view.

TROPICAL STORM ERIN: This storm system is boiling up in the central Gulf of Mexico (see photo above), north of Mexico's Yucatan peninsula. It has strengthened enough today to become the season's fifth named storm - Erin. It is expected to come ashore in South Texas Thursday morning. Here is the latest advisory. here is the predicted storm track. And here is a satellite view.

And here's more from NASA on all three storms. 

 

Posted by Frank Roylance at 11:10 AM | | Comments (0)
Categories: Hurricanes
        

August 14, 2007

Do it this weekend

Whatever it is, do it this weekend. If it's an outdoor thing, you're golden. If it's an indoor thing, take it outside. After a couple more really hot days - in the 90s again Wednesday and Thursday - we're in for a real summertime treat as a cold front cuts through here, possibly with some showers, to clear the decks for the weekend.

We're talking about daytime highs around 80 degrees, lows near 60 degrees, and no worse than partly cloudy skies. Look for lows in the 50s this weekend up at Deep Creek Lake.

Here's the forecast for BWI. Get ready to open those windows and shut off the AC. This is the mid-August break we all prayed for last week when it was 102 degrees in these parts.

Posted by Frank Roylance at 6:07 PM | | Comments (0)
Categories: Forecasts
        

The tropics are stirring

The statistical peak of the Atlantic hurricane season is approaching and, right on schedule, the tropical weather news is heating up. Hurricane forecasters are now watching two storm systems, one of which reached tropical storm strength this morning. 

Peak of season - NOAA

The first and least worrisome for the moment is Tropical Depression 4, renamed TS Dean this morning as winds topped 39 mph. It formed yesterday far out in the Atlantic. It is headed west, toward the Lesser Antilles, at more than 20 mph.

Here is the latest advisory on Dean. Here is the satellite view. And here is the storm track, the central line of which shows it becoming a hurricane threat to the U.S. Virgin Islands and Puerto Rico.

The newcomer this morning is a storm system gathering strength off the Yucatan Peninsula, in the central Gulf of Mexico. It is expected to strengthen today and pose a threat to the western or northwestern shores of the Gulf.

There is no advisory yet, but below is part of this morning's discussion from the National Hurricane Center. Here is the satellite view. And here is a map of sea surface temperatures. It shows the Gulf is very warm - primed to fuel the development of tropical storms and hurricanes.

"1007 MB LOW IS CENTERED NEAR 22N88W...OR JUST OFF THE N COAST
OF THE YUCATAN PENINSULA. THE ASSOCIATED TROPICAL WAVE IS JUST
OT THE W OF THE LOW CENTER. THE SYSTEM CONTINUES INTERACT WITH
AN UPPER LOW MOVING ACROSS THE W GULF OF MEXICO AND IS PRODUCING
WIDESPREAD CLOUDINESS WITH CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS OVER THE SE GULF...S OF 27N
BETWEEN 83W-90W. UPPER-LEVEL WINDS CONTINUE TO BECOME MORE
FAVORABLE FOR DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL
DEPRESSION COULD FORM LATER TODAY AS THE LOW MOVES TO THE WNW
NEAR 10-15 KT. INTERESTS IN THE W GULF OF MEXICO SHOULD CONTINUE
TO MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE
RECONNAISSANCE PLANE IS SCHEDULED TO INVESTIGATE THIS SYSTEM
TOMORROW AFTERNOON...IF NECESSARY."

Meanwhile, out in the Pacific Ocean, Hurricane Flossie is bearing down on the Hawaiian Islands. Here's the latest advisory. Twenty-five-foot surf anyone? Here's the infrared satellite view, and here is the predicted storm track. And here is what the Hawaiian newspapers are saying.

And here is a terrific view from orbit, just in.

Posted by Frank Roylance at 10:14 AM | | Comments (0)
Categories: Hurricanes
        

August 13, 2007

Very cool waterspout video

Waterspout - Dr. Joseph Golden, NOAAA feelance videographer has shot some really nifty video of a waterspout that appeared off the beaches of Pensacola, Fla. It's posted at CNN.com  Here's a link.

Some waterspouts form when tornadoes form, or move over water. But most have different origins. Here's more.  

Posted by Frank Roylance at 4:43 PM | | Comments (1)
Categories: Cool pictures
        

Forecasters watching tropical depression

Hurricane forecasters have their eyes on a storm now brewing in the far eastern tropical Atlantic. It's been labeled Tropical Depression 4, and could become the fourth named tropical storm of the 2007 Atlantic season. If so, it will be TS Dean.

Here's the latest advisory. Here's the satellite view. And here's the predicted storm track. It shows the storm becoming a hurricane by week's end, and a threat to the Caribbean islands. 

Posted by Frank Roylance at 11:21 AM | | Comments (0)
Categories: Hurricanes
        

Clouds obscure Perseid meteors

The wee hours of Sunday morning were clear, and forecasters insist the same will be true after midnight tonight. But at 1 a.m. this morning - the predicted peak of the 2007 Perseid meteor shower - the skies around Baltimore were shaded by low clouds, which later produced a rain shower in some spots.

Perseids -Thad V'Soske, in Colo.Isn't that just our luck? Those who turned out to watch for the meteors were largely disappointed. (Where skies were clear, the shower was reported to be thinner than expected, but nicely seasoned with spectacular fireballs.)

Nicole Fuller, intrepid Sun reporter assigned to be up in the middle of the night with video photographer Karl Ferron to cover the event from Alpha Ridge Park in Howard County, filed this report.

These disappointments happen. Some would say they happen most predictably when I write about an upcoming celestial event. But there is some consolation.

First, there are meteor showers - good ones - throughout the year, and if you turn out for enough of them faithfully, you will eventually be rewarded by a good show. And that will make you forget all the disappointments. (The Leonids in mid-November and the Geminids in mid-December are often very rewarding.)

Second, the Perseid shower has what veteran observers call a "broad peak." That means that, while the absolute peak, for us, occured behind clouds early this morning, the number of meteors is elevated for several days before and after. In fact, they were elevated early Sunday morning. Looking out at a starry sky, and worried that Monday morning's weather might be less than ideal, I ventured out between midnight and 1:15 a.m. Sunday. Under clear skies, spotted at least six meteors, five of them Perseids. 

Likewise, those who can get outside late tonight and early tomorrow morning should see more than the usual number of meteors flash across the sky. Many of them will be Perseids. And the weather forecast is, once again, promising.

Last night's ill-timed cloud cover was actually predicted yesterday by ClearSkyAlarmClock.com  It showed good "seeing" for Baltimore on Sunday morning and Tuesday morning, but opaque skies Monday morning. And that's what we got.

If you want to avoid similar disappointments in the future - and would like to be alerted when your skies look good for stargazing - a free subscription to ClearSkyAlarmClock is very helpful. Sign up, and they will email you every day when the forecast predicts good "seeing" at your location.  

For now, and for those of us who stayed up late last night only to be disappointed, here is a gallery with three pages of Perseid photos, shot from places where skies have been clear.

One more thing. One of our headlines, and some of the stories that have been running about the Perseid shower, have used language that suggests these showers "light up the sky" with meteors. Hardly. At their best, the Perseids arrive at rates of 50 to 100 per hour. That's roughly one a minute. It's a lot of meteors, and it can be very exciting and addictive to watch. But they hardly light up the sky. 

Only on the rarest occasions do meteor showers perform like that. The November Leonid shower in 1833 put on spectacular show. Abraham Lincoln and Frederick Douglass both witnessed, and wrote about that one. Here's more. In cases like that one, these "showers" are more properly described as "storms."

Posted by Frank Roylance at 10:17 AM | | Comments (2)
        

August 11, 2007

Flossie bears down on Hawaii

Flossie, the sixth named storm of the 2007 season in the northeast Pacific, is now a Cat. 3 storm with sustained winds of up to 132 mph. It is taking aim on the waters just south of the Big Island of Hawaii. Big surf headed their way.

Here's the latest advisory. There's no advisory yet because the storm is still too far from land.  Here's a satellite view. And here's the track forecast. Looks like the storm will pass south of the islands, with no direct hit. It's also forecast to weaken to tropical storm strength in the next few days. Wouldn't want to be on a boat out there, though.

 

Posted by Frank Roylance at 11:31 PM | | Comments (0)
Categories: Hurricanes
        

August 10, 2007

Why light pollution matters

As you head outdoors this weekend to watch the annual Perseid meteor shower, compare the starry sky you see (assuming skies are clear) with this photo of the night sky at Yellowstone Park in northwest Wyoming.

A Perseid meteor - NASAThe difference is light pollution. We have it. They don't. Just as trash obscures the beauty of our landscape, and air pollution obscures the view through our air, light pollution - unshielded electric lighting that is needlessly projected up instead of down where it's needed - obscures that night sky, and nearly all the stars and planets and the Milky Way that our ancestors knew so well.

It's our heritage, and it's been stolen from us. For more information, click here.

The Perseid shower has actually already begun, although the peak won't arrive duntil 1 a.m. Monday morning. Here is a gallery of Perseid photos that have already come in. Watch the gallery site for more. You can read more here. Here's the Saturday Sun story with more on the meteor shower.

And, if you do go out to watch the shower, come back here afterwards and let us know what you saw. Share the experience with those poor slackers who slept in.

Posted by Frank Roylance at 3:31 PM | | Comments (1)
Categories: Cool pictures
        

Indonesian quake rattles Va. well

Wednesday's big (7.5 on the Richter scale) earthquake off the coast of Indonesia near Jakarta sent seismic signals around the globe. When they reached the US Geological Survey's monitoring well near Christianburg, Va., they produced a noticeable fluctuation in water levels in the well.

As incredible as it seems, it's not unusual. The Christianburg well's sensitivity to major seismic events is well-known and long-watched by geologists and hydrologists. The well also shows regular rises and falls in response to the Earth's tidal movements. These are movements in the Earth's crust due to the gravitational pull of the sun and moon. They're the same forces that create ocean tides, except they're seen in the rock. And those movements cause the well water to rise and fall like water in a sponge.

Here is the data on the Indonesian quake, which occured at 1:04 p.m. EDT. And here is how the Christianburg well responded.

This is a longer look at how the well's water level responds to the regular pulse of Earth tides. You can also see that water levels in the well are falling this summer. 

Posted by Frank Roylance at 12:30 PM | | Comments (0)
Categories: Events
        

One hot August

Yesterday's rain cooled us down nicely, but the forecast ahead continues to show us facing mostly above-average daily highs well into next week. That means the month's cumulative average won't be trending sharply lower for a while. And that means this August, for a while, will continue to rank as the warmest on record for Baltimore, averaging 83.2 degrees so far, or 7.2 degrees above the long-term average.

Wednesday's daily average temperature was 91 degrees (high 102, low 80). That was 15 degrees above the long-term average for the date.

Since record-keeping began here in 1871, only four Augusts in Baltimore have ended with average temperatures of 80 degrees or higher. They were:

1900:  80.4 degrees

1938:  80.0 degrees

1939:  80.0 degrees

1995:  80.1 degrees

August 2007 is not likely to remain on top. The sun is slipping lower each day. The days are growing shorter, and the long-term averages should be tugging us into cooler territory. The average high for an Aug. 10 at BWI is 86 degrees, slipping to 82 degrees by Aug. 31. The average overnight low for today's date is 65 degrees, sliding to 61 degrees by month's end. This morning's low at the airport was 75. The forecast is calling for an airport high of 91.

 

 

Posted by Frank Roylance at 10:36 AM | | Comments (0)
Categories: By the numbers
        

August 9, 2007

Storm cools the air, wets the dust

Temperatures have dropped 29 degrees from where they stood yesterday at Baltimore-Washington International Airport. It was a record-setting 102 degrees at BWI yesterday afternoon. After today's thunderstorm passed by, the thermometer dropped from a high of 93 degrees to 73 between 1 and 2 p.m. Just before 4 p.m., with the sun back out, it has crept back up to 81.

Some locations saw more than an inch of rain, but most had less. Here's a sampling. And here's the cumulative rainfall map for the storm. It was the most rain BWI has seen in one day since July 10.

The rain hasn't ended the drought, but it has helped a bit. Here are some rainfall numbers, and temperature-drop readings for today from around the area:

BWI:  0.43 inch   93 to 73 degrees.

Dulles:  0 rain  96 to 81 degrees.

Reagan National:  0.02 inch  94 to 79 degrees.

Maryland Science Center:  0.31 inch   96 to 77 degrees.

Frederick:  1.17 inches  90 to 70 degrees.

The Sun:  0.21 inch   91 to 77 degrees. 

Posted by Frank Roylance at 3:49 PM | | Comments (0)
Categories: Events
        

Hurricane center tweaks 2007 forecast

NOAA

Hurricane forecasters at the federal Climate Prediction Center are sticking with their forecast of an unusually active 2007 Atlantic hurricane season. But their August forecast update has trimmed the upper end of the predictions issued in May.

Here's the full report.

The forecasters say water and atmospheric conditions in the Atlantic's main hurricane nurseries remain favorable for an above-normal season. The multi-decadal conditions that have given rise to unusually active hurricane seasons since 1995 remain in place, they said. And, the chances that a La Nina cycle will arise in the central and eastern tropical Pacific Ocean have actually increased a bit.

With all that, the forecasters have made few changes in the storm counts released in May. The August update released today predicts 13 to 16 named storms, seven to nine of which will become hurricanes. The May forecast called for 13 to 17 named storms and seven to 10 hurricanes.

The number of hurricanes predicted to reach Category 3 of higher remains unchanged, at three to five.

"Most of the atmospheric and oceanic conditions have developed as expected, and are consistent with those predicted in May," said Gerry Bell, lead seasonal hurricane forecaster at the National Oceanic and Atmospheric Administration's Climate Prediction Center in Camp Springs.

The biggest uncertainty was whether La Nina conditions would develop as expected in the Pacific. La Nina is a perdiodic cooling of the surface waters in the central and eastern tropical Pacific Ocean. The atmospheric changes that brings with it tend to encourage the development of hurricanes in the Atlantic.

"Today's El Nino/La Nina forecast ... indicates a slightly greater than 50 percent probability that La Nina will form during the peak of the hurricane season," Bell said. "But more importantly, we are already observing wind patterns similar to those created by La Nina across the tropical Pacific Ocean and Caribbean Sea that encourage tropical cyclone development."

"Conditions are ripe for an above-normal season," he said.

The Atlantic hurricane season typically peaks between Aug. 20 and Oct. 1. So far, three named storms - Andrea, Barry and Chantal - have formed in the Atlantic. None has struck land. NOAA officials said that number is slightly above normal for the season to date.

NOAA's hurricane forecast update comes on the heels of a similar update from Colorado State University storm experts Phil Klotzbach and William Gray. Citing "slightly less favorable conditions in  the tropical Atlantic," they cut their storm forecast from 17 named storms to 15; 9 hurricanes to 8; and 5 Cat. 3 storms to 4.

Both August forecasts remain well above the long-term averages for the Atlantic: 11 named storms, six hurricanes and two storms reaching Cat. 3 or higher.

 

Posted by Frank Roylance at 10:29 AM | | Comments (0)
Categories: Hurricanes
        

Downtown high Weds. was 106

It turns out that the actual high mark on the thermometer at the Maryland Science Center on Wednesday afternoon was 106 degrees F, not 105 as we reported. The higher reading came between the official hourly readings, but it still counts.

The highest temperature ever officially recorded for Baltimore was 107 degrees. That was on July 10, 1936, at the U.S. Customs House in downtown Baltimore. We were close, very close.

Stand by today for the latest U.S. Drought Monitor map, and an update from the National Hurricane Center as they revise their forecast for the current Atlantic hurricane season. Experts at Colorado State University have already reduced their predictions for the number of storms we can expect this season. The NHC is likely to do the same. The peak of the season begins in two weeks and runs into the first weeks of September.  

UPDATE: The new Drought Monitor map shows no changes from last week's. About three quarters of the state remains under moderate to severe drought conditions as measured by streamflow, rainfall and the condition of crops and foliage as measured by satellite. About half the state is in severe drought. Here is the map. And here is the national picture.

 

Posted by Frank Roylance at 10:12 AM | | Comments (0)
Categories: By the numbers
        

August 8, 2007

BWI sets record at 102 degrees; downtown 105

The thermometer out at Meltimore-Washington International Airport has reached 102 degrees this afternoon. That busts the old record of 99 degrees, set on this date in 1980.

It's 103 at the Maryland Science Center, and 102 degrees here at Calvert & Centre streets. The heat index here is 118 degrees. Yikes!.

UPDATE: The high this afternoon at the Maryland Science Center was 105 degrees. It looks like the 102-degree reading at BWI will hold. Reagan National in Washington reached 102 degrees today, beating the 100-degree record set in 1930. And Dulles International saw 100 degrees,  edging out the record of 98 degrees, set in 1980.

Posted by Frank Roylance at 3:53 PM | | Comments (1)
Categories: By the numbers
        

Heat index reaches 115

With the temperatures outside the Sun building now at 98 degrees, and 52 percent humidity (dew point 77 degrees), the heat index has reached 115 degrees at 12:30 p.m. If you're indoors, working in air conditioning, thank your lucky stars. This is truly dangerous heat and humidity.

It's 101 degrees at the Inner Harbor.

If you have a relative or a neighbor with cardiovascular disease, hypertension, diabetes, multiple sclerosis, dementia or some other chronic condition, please go check on them, or call them and make sure they're okay. Nearly all of the 13 Marylanders who have died this summer from heat-related causes also had underlying conditions that hampered their ability to tolerate and cope with the heat and humidity, and hastened their deaths.

Let's look after each other.

Posted by Frank Roylance at 12:30 PM | | Comments (0)
Categories: Heat waves
        

One hot night

Oh man, this is awful. The weather instruments here at The Sun were reading 93 degrees at 10 a.m. and they're still going up. The heat index numbers have been fluctuating between 109 and 112 degrees as the breeze causes humidity numbers bounce around. 

The overnight low at BWI was 80 degrees. A check with meteorologist Andy Woodcock, out at the NWS forecast office in Sterling, Va., found that this was only the third time since the official observations moved to BWI (Friendship) Airport in July 1950 that overnight temperatures have failed to drop below 80 degrees.

The other occasions were on June 26, 1952 and July 22, 1972.

The list is much longer if you include all dates since weather records began in Baltimore in 1871. Back then, the readings were taken in downtown Baltimore, where heat-island effects cause higher daytime temperatures, and retard overnight cooling.

Development and paving at BWI may be contributing to a heat island effect out there, too.

Here at Calvert & Centre streets, the low this morning was 84 degrees. It was 85 at the Maryland Science Center. 

Mercy.  

 

Posted by Frank Roylance at 10:55 AM | | Comments (0)
Categories: Heat waves
        

August 7, 2007

A really nasty day

It's hot. It's humid. And it's very still. It's, well, summer in Baltimore. Seven out of the last eight days have reached the 90s at BWI. The highest reading was 98 degrees, on Saturday. We could come close to that again today.

NASA photoHere's the official forecast. Not much relief in sight yet, although we should slip back into the 80s for the weekend. The Baltimore Health Department has issued another Code Red Heat Alert, and extended it through Wednesday, too. Plenty of others share our misery. Here's the national map, showing heat advisories and warnings in orange and purple.

How hot is it? Click here. Ready to cool off? Try Seattle.

August is running more than 5 degrees warmer than the long-term averages for BWI. Seven of the last eight days (including today) have reached the 90s. The high mark was 98 degrees, on Saturday. We may challenge that number today. In all, we have had 26 days in the 90s since May 1. Last summer's total was 39 days, but we have three weeks to go.

We have set no new records yet this summer. But a 96 degree reading out at Dulles International Airport on Monday afternoon tied the old record for an Aug. 6 there, set back in 1977. We will be hard-pressed to bust today's record high of 105 degrees, set during a Baltimore heat wave in 1918.

Air quality has not been too bad, actually. You can follow developments here.

We remain very dry, too, more than 5 inches behind the average pace since May 1 at BWI. It's worse in many other parts of the state.

 

 

Posted by Frank Roylance at 11:09 AM | | Comments (2)
Categories: Forecasts
        

Utah mine collapse on seismographs

The mine collapse that has trapped six Utah coal miners a quarter of a mile beneath the surface of the Earth was detected on seismographs in Utah and reported initially as a minor (3.9) earthquake. Here is that early quake report. A University of Utah scientist says there have been about 20 mining-related quakes recorded since 1978.

Shallow quakes in Utah are not unusual. Here's a map of recent tremors.

Posted by Frank Roylance at 10:28 AM | | Comments (0)
Categories: Events
        

August 6, 2007

Is your well getting low?

Marylanders who rely on well water may be noticing their water tables are falling. Or at least they're worrying about their water and limiting their washing and sprinkling and flushing as a result.

The US Geological Survey has identified two Maryland monitoring wells that dropped to record lows by last month. The first is in Frederick County, the other in Charles County. Data collection at those wells only goes back to the 1980s, so we can't say these are historic lows, exactly. But hydrologists say the levels seen last month were lower than during the drought in 2002, which was pretty severe. 

Here's the data for the Frederick well. Here's the same for the Charles well.

If the drought continues, more monitoring wells are expected to touch record lows. And more families will be following the old well-water adage:  "If it's yellow, let it mellow. If it's brown, flush it down."

Even the Aussies have kicked that ball around. Here's a clip from last summer's drought down under. Anybody out there in the Maryland countryside worried about their well water? Do you eschew the casual flush?

Posted by Frank Roylance at 4:52 PM | | Comments (2)
Categories: Drought
        

Annapolis wins rain lottery

Yesterday's rain was a spotty and not-very-satisfying affair. Annapolitans got the best of it by far. The weather instruments at the Naval Academy registered an inch of rain, nearly all of it in a heavy rain early in the evening. But most of the rest of us got only enough to wet the topsoil and puddle the streets. Here's a sampling:

Annapolis:  1.00 inch

BWI: 0.13 inch

The Sun: 0.13 inch

Reagan National: 0.31 inch

Ocean City:  0.17 inch

WeatherDeck (Cockeysville): 0.21 inch

In any case the drought continues. Even at BWI, where a heavy and very localized rain on July 10 skewed the numbers, the record books show a rainfall deficit of 5.22 inches since May 1. Yesterday's showers may mean some minor improvement on this week's Drought Monitor map. It will incorporate data through Tuesday. It's due for release Thursday morning. Here's last week's map.

It looks like today will be yet another 90-plus day at BWI. So far (through Sunday) we have had 25 days in the 90s this season. That compares with 31 days by this time last year. That summer ended with 39 days of 90-plus weather. The difference so far lies in July. We had just 10 July days in the 90s at BWI, compared with 18 days in July 2006. 

The first week of August last year was the hottest of the summer, with several days in a row of 100 degrees or more, both downtown and at BWI. Our forecast for the week looks pretty dang hot, but not quite as bad as last year.

Posted by Frank Roylance at 10:41 AM | | Comments (0)
Categories: Drought
        

August 4, 2007

Hurricane forecast revised

Colorado State University hurricane experts Phil Klotzbach and William Gray have revised - downward - their forecast for the 2007 Atlantic hurricane season. Cooler sea surface temperatures in the tropical Atlantic and infusions of atmospheric dust from the Sahara have made the Atlantic's main hurricane nursery more stable than they anticipated in their May forecast. So their storm estimates are lower.

Hurricane Fran - NASABut it's not a dramatic revision. Klotzbach and Gray are now anticipating 15 named storms this season, down from 17 in their May forecast. Two of those storms have already come and gone without effect. (They don't count Andrea, which got a name but wasn't exactly a tropical storm.)

They're forecasting 8 of those storms to become hurricanes (down from 9 in their May forecast). And they expect 4 will reach Category 3 on the Saffir-Simpson scale of hurricane intensity (down from 5).

That still qualifies as a more active season than the long-term averages. 

As for strike probabilities, they put the chance that a storm of Cat. 3 or higher will strike the US East Coast at 43 per cent (compared with 31 percent in the average season over the last century). The risk of a Cat. 3 storm striking the Gulf Coast was put at 44 percent (compared with 30 percent over the last century).  Overall, the chance of a strike anywhere on US territory is 68 percent, they said, compared with an average of 52 percent.

Here's the full report. Here's the National Hurricane Center main page. The current hurricane season ends Dec. 1. By the way, that's Hurricane Fran (1996) in the satellite photo.

Posted by Frank Roylance at 8:44 PM | | Comments (0)
Categories: Hurricanes
        

August 2, 2007

Half state now in "severe" drought

The new USDA Drought Monitor map is out today, and it shows that Maryland's drought continues to worsen. Half the state - 50.5 percent - is now considered to be in "severe" drought, as measured by rainfall, streamflow and damage to vegetation. That's up from just 17 percent last week, and zero percent on the July 10 map.

Here's the new map, which reflects data as of July 31.  It shows that the worst-hit parts of the state - once confined to Southern Maryland and portions of Washington, Allegany and Montgomery counties - now also include much of the Eastern Shore, from the Bay Bridge south, almost to the ocean and the Virginia line.

Over all, about 75 percent of Maryland is in either moderate or severe drought. That's unchanged from last week, but more of what had been just "moderate" drought has slipped into the "severe" category.

Those portions of the state have had little or no significant rainfall since mid-April.

The remaining 25 percent of the state, including far Western Maryland and the northeastern corner of the state, remains only "abnormally dry."         

Here's how our state fits in with the deepening drought across much of the rest of the Eastern United States, with the partial exception of New England.

The prospects for relief, meanwhile, appear dim. There's only a "slight" chance for thundershowers in the next few days, then more heat and blue skies. These summer droughts are often broken by the passage of tropical storms or their remnants. The only hope glimmering on that front is now in the eastern Caribbean, where hurricane forecasters have begun watching a new storm system. Here's the satellite view.  And here's a portion of the forecasters' discussion:

"A TROPICAL WAVE AND AN AREA OF LOW PRES IN THE E CARIB IS MOVING
WWD NEAR 20 KT. A SATELLITE LOOP BEGINNING AT 00Z TODAY SHOWS
CONVECTION SIGNIFICANTLY INCREASING IN BOTH COVERAGE AND
MAGNITUDE...ALTHOUGH CLOUD TOPS HAVE WARMED A BIT OVER THE PAST
HOUR OR TWO. CURRENTLY...SCATTERED TO NUMEROUS MODERATE
CONVECTION IS FROM 13N-17N BETWEEN 64W-70W. WHILE CONVECTION IS
IMPRESSIVE IT REMAINS CHALLENGING TO FIND THE LOW-LEVEL CENTER.
THIS SYSTEM CONTINUES TO HAVE SOME POTENTIAL TO BECOME A
TROPICAL CYCLONE DURING THE NEXT DAY OR SO. AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IS CURRENTLY ENROUTE TO INVESTIGATE
THE SYSTEM."

If it becomes the season's fourth tropical storm, it will be named Dean.

Posted by Frank Roylance at 5:02 PM | | Comments (0)
Categories: Drought
        
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This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff
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