September is, statistically at least, the peak of hurricane activity in the Atlantic basin. But this year has been notably anemic.  We were busier in August.

Only two named storms cropped up during the month that ends tonight, compared with four in August. Tropical Storm Erika formed east of the Leeward Islands on Sept. 1, drifted westward for three days and wheezed to an end southeast of the Dominican Republic. Winds peaked at about 60 mph., and the storm dumped a lot of rain on the islands. 

Fred was a bit more impressive. It formed Sept. 7 and blew up to hurricane force before expiring Sept. 12 near where it was born in the far eastern Atlantic. Fred was only the second hurricane of the season.

Tropical Depression 8 formed briefly on Sept. 25, but fell apart the next day without growing strong enough to earn a name.

Jeff Masters, on his Wunder Blog, is calling this the quietest September in the Atlantic since 1997. 

In all this season, the Atlantic Basin has generated just six named storms, including two - Bill and Fred - that reached hurricane force. In fact, both Bill (Aug. 15-24) and Fred reached "major" (Cat. 3) strength.

The U.S. mainland has been spared. Tropical Storm Claudette, in mid-August, stirred things up along the Florida/Alabama Gulf Shore. Bill kicked up a lot of wind and waves along the Atlantic coast all the way to the Canadian Maritimes before expiring in the Atlantic. The photo above shows Ocean City, N.J. beachgoers getting a briefing on Bill-caused rip currents. 

Danny did the same in the Carolinas late in the month before being absorbed by a frontal system. But that was about it, to the relief of millions. 

Hurricane forecasters have been lowering their expectations all season, pointing to the moderate El Nino conditions developing in the Pacific Ocean. El Ninos tend to suppress hurricane formation in the Atlantic.

Back in late May, for example, Colorado State University prognosticators William Gray and Phil Klotzbach forecast 11 names storms, with five predicted to become hurricanes, and two that would reach "major" proportions.

In June, the National Hurricane Center expected 9 to 14 named storms, with four to seven hurricanes one to three "major" storms.  

By August, CSU had cut its forecast to 10 names storms, with four hurricanes, two reaching major status. The feds were by then looking for seven to 10 named storms, with three to six hurricanes, one to two becoming major.

Give them credit. We have seen two major hurricanes. And we could still see some additional activity. But there is nothing happening in the tropics at the moment. 

(Top, AP Photo/Jim Gerberich; Bottom, SUN PHOTO/John Makely/Surfing Isabel's waves in Ocean City, Md., 2003)

Posted by Frank Roylance at 4:54 PM | Permalink | Comments (1)
Categories: Hurricanes
        

Pretty sure this is the first mention of frost in the NWS forecasts for Maryland this season. They've issued a frost advisory for the high country out in Allegany County, including the cities of Frostburg and Cumberland, where overnight lows are headed for the 30s.

We won't see anything like that down here in the lowlands. But after a patch of showers passes by later today, we should see some rapid clearing as high pressure moves into the area. The clear skies and diminishing winds open us up for some radiational cooling tonight. And that will send our overnight temperatures into the 40s, for what will likely be the coldest night of the season so far. 

So by Thursday morning it will really feel like October.

It's good news for stargazers, of course. Clear, cool, still skies are great for looking out at the universe. The moon has now moved past Jupiter, but the big planet is still big and bright in the southeast in the evening. With a good pair of binoculars, you should be able to make out as many as four of the Galilean moons, lined up in a row on either side of the planet's disk.

If you're up before dawn Thursday, look due east for a view of bright Venus low on the horizon. This is also a good time to catch a glimpse of elusive Mercury, rising just below (and just after) Venus. Mercury is followed by Saturn a short while later, but the brightening dawn will likely begin to fade the show. For a sky map, click here, and scroll down to "This Week's Planet Roundup."

Mercury, as you may have read, was visited Tuesday evening by NASA's Messenger spacecraft, which flew within 142 miles of the tiny planet just before 6 p.m. Scientists at the Johns Hopkins University Applied Physics Lab have been downloading science data from the flyby this morning. Messenger is due to enter orbit around the planet in March 2011.   

Posted by Frank Roylance at 10:07 AM | Permalink | Comments (0)
Categories: Forecasts
        

Weather watchers in Maryland noticed something odd on Monday. Their barometers were skidding to unusually low numbers, while the skies outside seemed strangely clear. Normally, when the barometer is very low, we're in the middle of a pretty impressive storm.

Fred Weiss noticed and shot me an email message from Baltimore: "What is causing this low pressure?" he asked.

I checked, and he was right. The official National Weather Service barometer out at BWI-Marshall Airport sank to 29.44 inches. Out on the WeatherDeck in Cockeysville, the console said 29.37 inches. And here at The Baltimore Sun, Calvert and Centre streets, the weather station read 29.45 inches.

Steve Zubrick, science and operations officer for the NWS at Sterling says the last time BWI saw a reading that low was back on April 7, 2009.

Anyone else make a note of their low reading for Monday?

For comparison, I checked the low barometer reading back on Sept. 19, 2003, when Tropical Storm Isabel blew through the region. The low reading at BWI that morning was 29.58 inches.  So, I checked back ever farther, to Hurricane Hazel, on Oct. 15, 1954. The low barometer that day was 28.93 inches.

So Monday's low reading was a bit lower than during Isabel, but not nearly as low as during Hazel's passage. 

So what was going on here Monday? And more specifically, why was the sun shining?

Our low barometer was caused by an intense low-pressure system that was - and still is - drifting across the Great Lakes and southeastern Canada. A trough of low pressure extends south and west from that storm center, which is what is keeping our barometric readings so low even today - Tuesday. The Sun's barometer has only rebounded to 29.69 inches at 11 a.m.

Here's a nifty satellite loop of the spinning low.

The low is rotatring counterclockwise. And on Monday morning, it was setting off torrential rains along the Great Lakes, where I was visiting my in-laws in Erie, Pa. It also touched off a band of intense showers along the I-95 corridor in the late afternoon at one point (where it whacked us again as we drove back into Baltimore.) We recorded a quick tenth of an inch here at The Sun.

The big low was also dragging a wedge of dry air in from the southwest, which gave Baltimore the sunny skies we saw for a time Monday. Meteorologists call that a "dry slot," and it's not unusual with these strong lows. You can see it in the satellite image above, now just off the East Coast.

Some clouds have moved in behind it as cooler, drier air is pulled down from the northwest around the backside of the low. 

The forecast calls for windy conditions today as the atmosphere continues to flow around the low to our north and east. But we should remain sunny, with a high near 70 degrees.

As cooler air moves in with high pressure builds into the region behind the low, we'll start hanging up in the mid- to upper-60s for the next few days.  We'll stay sunny until the next cold front approaches late Friday into Saturday. 

Posted by Frank Roylance at 10:48 AM | Permalink | Comments (2)
Categories: By the numbers
        

Tropical Depression No. 8 has formed in the far eastern Atlantic Ocean, according to the National Hurricane Center. It could become the season's seventh named storm - Grace - later today or tomorrow.

But conditions are not favorable for the storm's continued growth. Once again, strong wind shear aloft is expected to cut this disturbance down to size. 

The storm is 500 miles west of the Cape Verde Islands, with top sustained winds of just 35 mph. It is moving northwest at 14 mph and poses no immediate threat to land. And from the look of the forecast track, never will. 

Here is the latest advisory. Here is the forecast storm track. And here is the view from orbit.

Posted by Frank Roylance at 5:34 PM | Permalink | Comments (0)
Categories: Hurricanes
        

Maybe this would be a good day to visit the book festival in Mt. Vernon and stock up. We should have sunshine today. But forecasters out at Sterling have posted a pretty gloomy set of predictions for the next few days, with on-and-off rain - some of it heavy at times - in the cards for Central Maryland. So it just seems like a good weekend to buy early and curl up with a good book.

The problem is a stalled cold front - the one that dropped down across the region overnight, bringing us a little light rain and cutting off the 80-plus temperatures and high humidity we've experienced in recent days. What we're left with are cool-to-mild temperatures that may not get much past 70 degrees today (Friday), and may not exit the 60s on Saturday - a few degrees colder than the long-term averages for this time of year.

And rain. Low-pressure systems tracking along the cold front from the Ohio Valley will be responsible for the rain that's forecast to pick up late Saturday. That rain could get heavy at times, with 1 to 2 inches possible overnight into Sunday. Maybe that will bring the month's rainfall - just 2 inches at BWI-Marshall so far - more into line with long-term averages.

Another cold front early next week will likely bring more showers before we break out into the sunshine again by Tuesday. But it will feel more like October, with highs only in the upper 60s.

(PHOTO: Baltimore Office of Promotions and the Arts)

Posted by Frank Roylance at 10:47 AM | Permalink | Comments (0)
Categories: Forecasts
        

The flooding in Georgia this week has made for many remarkable photos. But none had the vantage point of orbiting satellites.

Digital Globe, a satellite imaging company, has released an photo of the flooding around the Six Flags over Georgia amusement park, and there's not much amusing about it.

Aside from the still, brown water that had swamped some of the roller coasters and other parts of the park by Tuesday when the shot was taken, what's really amazing is the detail available from cameras gliding by hundreds of miles up.

Can you imagine the detail available from the Pentagon's spy sats? Smile!

Here's the photo. And here's a more detailed version.

Posted by Frank Roylance at 3:18 PM | Permalink | Comments (2)
Categories: Cool pictures
        

I admit it. After weeks of blessed fresh air and breezes through the house, Wednesday's summer-like humidity got to me. Tonight, I switched on the AC.

I know. I know. We were saving a bundle having the AC off for weeks on end, through what's been mostly a delightful September. And we might have lasted until Nov. 1 without turning on the AC or the heat and handing over our paychecks again to BGE.

But trust me. By the time I got home tonight, the temperature upstairs was 81 degrees, with a relative humidity of 88 percent. My wife was, um, glowing. The stuff in the fridge was sweating. All the windows were open and it provided no relief at all. The humidity had been even higher Tuesday night - as much as 99 percent on the WeatherDeck.

So I caved. I kicked on the new Bryant. Now there's a cool, dry breeze in the house, stirred by fans. And all is well. May even throw on a blanket tonight.

This weakness of mine should only last a day. Temperatures by Friday and Saturday will be cool, near 70 or even lower. And dry. We'll open up again and breathe freely once more.

So how long can you hold out this autumn before you turn on the heat?  

Posted by Frank Roylance at 8:49 PM | Permalink | Comments (5)
Categories: Saving energy
        

Heavy and persistent rains have swamped many sections of the Deep South in recent weeks.  It has erased longstanding drought in many spots, but replaced it with terrible flooding that has caused numerous deaths - at least seven in Georgia alone - and much property damage.

NASA's Earth Observatory has computed cumulative rain totals based on satellite observations and generated a map of the region showing where the heaviest rain was concentrated.

The lightest amounts are in pale green, the heaviest (more than 300 mm, or about 12 inches) in dark blue. Here's more.

Posted by Frank Roylance at 12:15 PM | Permalink | Comments (1)
Categories: By the numbers
        

There's more sunshine out there today (Wednesday) than forecasters expected, and plenty of humidity. That's making it feel more like late summer than early autumn. Highs this afternoon and tomorrow could reach the low to mid-80s, about 8 degrees above the norms for this time of year in Baltimore. But time is running out.

Forecasters out at Sterling say this southerly flow of warm, humid air will be cut off by an approaching cold front , now over the Great Lakes, that's expected to cross the region late on Thursday. As that front gets close, it could bring us widely scattered showers later on Thursday. But it will also bring a wind shift that should begin to clear the air and dry us out for Friday and Saturday.

It should also cool us off. Friday will be sunny and pleasant, they say, with highs near seasonal norms, in the low 70s. Saturday will be even cooler, perhaps stalling out in the upper 60s under partly sunny skies. A breath of autumn.

The next round of rainy weather could show up as early as late Saturday and Sunday, clearing as the workweek begins.

Speaking of rain, I notice that the Drought Monitor map last week once again included some "abnormally dry" conditions in far western Maryland - about 13 percent of the state. It's the first time since mid-August that Maryland has shown up on the drought map.  

The dry patch is part of a larger expanse of scarce rainfall that includes southwestern Pennsylvania, northern West Virginia and eastern Ohio.

(SUN PHOTO/Amy Davis 2004)

Posted by Frank Roylance at 11:01 AM | Permalink | Comments (0)
Categories: Forecasts
        

The fall, or autumnal equinox arrives this afternoon just as the rush hour begins - at 5:18 p.m. That's the moment when the the sun, as seen from Earth, crosses the planet's equatorial plane and heads for the southern hemisphere. And, the sun rises due east today.

Or, you could say the Earth's northern hemisphere is no longer tilted toward the sun, or the length of the night is equal in both the northern and southern hemispheres. You can also note the place on your western horizon where the sun sets, and watch in the coming days and weeks how quickly that spot moves to the south.

It is the official end of summer and the beginning of autumn for the northern hemisphere, and the first day of spring for those south of the equator. So we're off to work today in summer, and return home tonight in the fall.

You can read more about the equinox here.

(NASA illustration)

Posted by Frank Roylance at 7:36 AM | Permalink | Comments (7)
Categories: Almanac
        

I know, I know. I dropped the ball. That nocticlucent cloud experiment we wrote about here early last week was postponed on Tuesday night due to bad weather. And when it finally got the green light on Saturday, I was asleep at the switch, trying to have a life away from work. Mea culpa.

Anyway, the launch at around 7:45 p.m. produced the predicted artificial cloud in the the sky, which was visible from many locations on the East Coast.

Here is the CNN story, and another from Space.com. Here is a Flickr post showing what the cloud looked like, although the shooter had no idea what it was.

Finally, here is some You Tube video of the actual event, shot from Eldersburg, Md. The very bright, steady light in the sky is the planet Jupiter.

(NASA photo)

Posted by Frank Roylance at 7:04 PM | Permalink | Comments (1)
Categories: Sky Watching
        

The National Weather Service thermometer at Baltimore-Washington International Thurgood Marshall Airport dropped to an official 47 degrees this morning. You can credit clear skies amid dry Canadian high pressure, and radiational cooling. All the warmth we built up under Saturday's perfect blue skies just radiated back out into space overnight.

Lows in the 40s felt pretty darn cold if you went to bed with the windows open last night. But it was still 5 degrees short of the record. The coldest morning for Baltimore on a Sept. 20 is 42 degrees, last reached on this date in 1959.

The last time we were this cold at the airport was back on June 1, when the mercury touched 46 degrees.

We reached 44 degrees out here on the WeatherDeck in Cockeysville (left). And there were some even colder readings across the region - as low as 41 degrees just over the Pennsylvania line. Sunshine today will bring us back into the 70s. Another fine late-summer afternoon; of course, it can't last.

The high pressure system is moving off the coast today, and we will come into the return flow of the clockwise circulation around the center, bringing us increasingly warm and moist air.

That will mean more clouds, and eventually rising chances for rain and showers as the week rolls along. 

Posted by Frank Roylance at 9:54 AM | Permalink | Comments (1)
Categories: By the numbers
        

With the clatter of rain in the gutters overnight and this morning, we've managed to pick up another inch of rain here on the WeatherDeck in Cockeysville. That puts the WeatherDeck past 4.6 inches for the month - well above the long-term averages for the area for all of September. But the official station for the region, at BWI, has recorded only 2 inches, so no surplus there.

Skies should begin to clear tomorrow as high pressure approaches from the north. The weekend looks good - sunny skies and highs in the 70s.

Down at BWI-Marshall, the weather service instruments have recorded only a few hundredths of an inch since yesterday (Wednesday). But totals are higher in other places around the region.

Dunkirk (Calvert):  1.38 inches

Jacksonville (Baltco):  1.15 inches

Chesapeake Beach (Calvert): 0.78 inch

Jarrettsville (Harford):  0.45 inch

Salisbury (Wicomico):  0.26 inch 

So are we liking this rain? And the cool weather? It's only 59 degrees on the WeatherDeck at 10:30 a.m. No AC, no heat ... nice to keep that money in our pockets.

Posted by Frank Roylance at 9:59 AM | Permalink | Comments (1)
Categories: Forecasts
        

Marylanders enjoyed a relative cool summer this year, at least until August turned things around and ended the three-month meteorological season about average.

But at least there were few 90-degree days - only 10 all summer. That tied with the years 1883, 1884, 1904 and 1907 for the 8th fewest days in the 90s since record-keeping began here in 1871.

But even if the weather seemed relatively cool here for part of the summer, the National Oceanic and Atmospheric Administration reminds us that the planet's land and sea-surfaces were unusually warm.

August temperatures around the globe - land and ocean surface - were the second-warmest on record, after 1998. The NOAA illustration above shows above-average temperatures in pink and red. Below-average temperatures are in blue.

NOAA said that during the last three months - the northern summer, southern winter - the globe's averaged ocean surface temperature was the warmest on record for that period. The data go back to 1880. The combined average land and ocean surface temperature was the third-warmest on record, up 1.06 degrees F. from the 20th century average.

And so far this year - January through August - combined average land and sea-surface temperatures for 2009 are tied with 2003 for the fifth-warmest such period on record. You can read more here.

Posted by Frank Roylance at 3:01 PM | Permalink | Comments (3)
Categories: Climate change
        

The clouds are closing in, bringing what forecasters say will be several days of likely rain for the region. So today's delightful late-summer forecast of sunshine and blue skies may be the last we see until Sunday.

For now, we're under the influence of a big high pressure system over Eastern Canada. But there is a cold front approaching from the north, and that will bring a gradually increasing cloud cover with more easterly winds late today, and eventually rain. Forecast rain chances climb to 70 percent in the next few days as lows moving along the stalled front drag in more moisture from the ocean and the Gulf.

BWI-Marshall has had almost 2 inches of rain so far in September, just about normal for the month to date.

There is no change yet in the forecast for the beaches, and tonight's planned launch of a 65-foot Black Brant XII rocket from the NASA Wallops Flight facility on Virginia's Eastern Shore. Scientists plan to release a high-altitude cloud of aluminum particles that may be visible from much of the mid-Atlantic region.

The launch window opens at 7:40 p.m. and closes at 7:57. Forecasters gave the launch a 60 percent chance of favorable weather. There's more on the event in the previous post.

Here is the Wallops forecast. Looks a lot like ours.

Posted by Frank Roylance at 8:02 AM | Permalink | Comments (0)
Categories: Forecasts
        

UPDATE: 8:00 p.m. Tonight's launch attempt was scrubbed due to bad weather. No word yet on when they will try again. Earlier post follows:

Sky watchers in the mid-Atlantic region may get a look at an odd artificial cloud Tuesday night after it's released from the fourth stage of a rocket set for launch from NASA's Wallops Flight Facility on the Eastern Shore.

The cloud of aluminum particles from the rocket's exhaust is expected to provide scientists with insights into the physics of "noctilucent clouds," the highest natural clouds (around 50 miles up) that form in the Earth's atmosphere. That's a NASA photo of such clouds, above.

The experiment, called "Charged Aerosol Release Experiment" (CARE), is being conducted by the Naval Research Laboratory and the Pentagon's Space Test Program. Also involved are NASA, the University of Michigan, the Air Force Research Laboratory, Clemson, Stanford and Penn State universities, the University of Colorado and MIT.

The launch window for the experiment opens at 7:40 p.m. Tuesday, and closes at 7:57 p.m. Weather forecasters gave the launch a 60 percent chance of favorable weather. Clear skies are needed up and down the coast to provide multiple camera locations with a view of the cloud.

Backup dates for the launch are each evening Sept. 16-20, but the weather is expected to deteriorate this week. The next opportunity would come next month.

The experiment is being carried by a 65-foot Black Brant 12 rocket, a sub-orbital vehicle used frequently by scientists at Wallops. The rocket is programmed to climb 180 miles above the Earth - much higher than the altitude of natural noctilucent clouds - and 98 miles down range (east) from Virginia's Eastern Shore.

Observers should watch for the cloud to be released about six minutes after launch. If skies are clear, the sinuous white cloud should become visible in the eastern sky after its release.

To follow the launch via Webcast, http://sites.wff.nasa.gov/webcast.  For Twitter updates, go to http://twitter.com/NASA_Wallops. Or call the recorded updates at 757-824-2050.

And as always, any WeatherBlog readers who see it are invited to come back here and leave comments describing the event for those who miss it.

Posted by Frank Roylance at 6:04 PM | Permalink | Comments (0)
Categories: Sky Watching
        

Once-a-Hurricane Fred, which never posed a threat to land, has stalled far out in the Atlantic and fizzled to below tropical storm force. The National Hurricane Center today issued its final advisory on the storm.

Fred formed in the far eastern Atlantic on Sept. 7, and by late the next day had reached hurricane strength. It soon became the second major (Category 3) hurricane of the 2009 Atlantic season. It's top sustained winds reached 115 mph at one point.

But the storm never seemed to get into gear, and drifted slowly at sea for several days before finally fading. It still has something of its spiral shape (above), but has now lost its central convection - the engine that drives hurricanes - and been demoted to a weak "remnant low" posing a threat only to shipping.

The hurricane center, meanwhile, is watching some rainy non-tropical weather in the Gulf of Mexico, and a poorly organized low coming off West Africa.

Here is the final advisory on Fred. Here is the storm track. And here is the view from orbit.

Posted by Frank Roylance at 5:09 PM | Permalink | Comments (0)
Categories: Hurricanes
        

 Chilly? Looks like this afternoon's official high temperature at BWI-Marshall will be 62 degrees. If so, that will be just one degree higher than the all-time "low maximum" for a Sept. 11 in Baltimore - 61 degrees, which has stood since this date in 1883.

All that and a gusher of rain, too - an inch and a half at BWI, and 1.4 inches here at The Sun.  

The sunshine returns on Sunday, of all days.

Posted by Frank Roylance at 4:35 PM | Permalink | Comments (0)
Categories: By the numbers
        

Awoke this morning to the sound of rain on the WeatherDeck in Cockeysville. After more than a week of rainy forecasts and dry skies, the storm that's been loitering off the Carolinas and bluffing about a drift inland finally made a move our way overnight.

There was heavy rain - about 5 inches  since noon Thursday - in Ocean City, closer to the low's center off Delmarva overnight, and the rain finally headed our way early this morning. We've got more than 1.5 inches of new rain in the gauge on the WeatherDeck. Baltimore-Washington International Thurgood Marshall Airport had something closer to three-quarters of an inch at 7 a.m. Ditto for The Baltimore Sun's weather station at Calvert and Centre streets downtown.

Washington's Reagan National and Dulles airports have received far less rain this morning. More rain seems to be moving onto the cities to our north, including Philadelphia, where they've seen more than an inch, and Wilmington, Del., with an inch.

Here are some of the highest 24-hour rain totals from across the region:

Berlin: 5.88 inches

Salisbury: 3.11 inches

Jacksonville:  2.3 inches

St. Michaels:  1.9 inches'

Cockeysville: 1.88 inches

Jarrettsville: 1.82 inches

Pasadena:  1.45 inches

Towson:  1.33 inches

Catonsville:  1.21 inches

Columbia:  0.87 inch

Crofton:  0.80 inch

Here are more tallies.

Forecasters out at Sterling say the center of the low, now off the Delaware beaches, will be drifting out of the region over the next 24 hours, That will draw much drier air our way from the southwest. It's already sunny in Harrisonburg, Va.

The northeastern portion of the state will be the last to shake free of the lingering showers and cool temperatures, while the Shenandoah Valley enjoys sunshine and highs in the 80s. Our weather should look brighter by Sunday and Monday, with sunny skies and highs in the low 80s.

(SUN PHOTO by Frank Roylance)

Posted by Frank Roylance at 7:15 AM | Permalink | Comments (2)
Categories: Events
        

The forecast from the National Weather Service has been calling for rain in Baltimore every day since the middle of last week. They pointed to a coastal storm and winds off the Atlantic bringing lots of clouds and moisture into the region.

Well, seems like we've had plenty of clouds, and cool temperatures. But the airport has recorded barely a quarter-inch of rain. And out on the WeatherDeck in Cockeysville, we've noted less than a tenth of an inch all month.

Somehow, we've stayed just far enough west and north of the action to remain pretty nearly dry all week. But can we duck the rain much longer?

The official forecast out of Sterling pushes the likelihood of showers today and tomorrow to 70 percent. And tonight's odds are set at 100 percent. If the wettest end of their predictions proves correct, the city could see more than 2 inches of rain between now and Friday night. Any bets?

UPDATE 2:30 p.m. Thursday: Forecasters have already backed off earlier rain amounts. Rain chances this afternoon are now 20 percent, not 70 percent. 

A Coastal Flood Advisory remains in effect through early Friday morning for the Western Shore, from Harford to St. Mary's counties. Tides may run up to 18 inches above predicted levels late Thursday as persistent northeast winds continue to push water onto the beaches and up the creeks.

Winds may pick up, too, as that coastal low continues to hang out near the mouth of the Chesapeake. Gale warnings are posted for the Maryland portion of the Chesapeake through midnight Thursday night as the low approaches. 

Conditions look dicey for the beaches, too, with Coastal Flood, High Surf and Wind advisories posted for Ocean City. Gusts could reach 45 mph. Tides could be 2.5 feet above predictions, and the risk of rip currents is high.

Be careful out there.

Posted by Frank Roylance at 11:14 AM | Permalink | Comments (1)
Categories: Forecasts
        

Today, Maryland Weather  - the WeatherBlog, the Baltimore Sun's first online Web log - is five years old.

In the last 60 months we have posted almost 2,500 entries, and more than 2,200 reader comments. As we got the hang of this new medium, we have gradually added Web links, pictures and videos. And in July 2006 we began writing weather comments on Page 2A of the print editions.

Our weekly online page views now average around 14,000, but when snowstorms or hurricanes threaten Marylanders, that number can surge to more than 120,000. We generally rank between 10th and 20th of The Baltimore Sun's blogs in weekly reader traffic, not bad for a blog that has nothing to do with sports or eating.

The Sun's Davis Pro 2 weather station, at Calvert and Centre streets, which we pushed for, and made accessible through The Sun's weather page at MarylandWeather.com, gets 30,000 to 40,000 hits a month.

Curiously, while everyone has some need to know about the weather, that's not the topic here that seems to generate the most enthusiasm. In a week without snow or hurricanes in the forecast, it's our posts about the night sky that seems to generate the most reader interest.

Whether it is a passing comet, an expected meteor shower, and prominent display of bright planets or a flyover by the International Space Station, readers seem to get the biggest kick out of being plugged in to celestial events they might otherwise have missed.

After 35 years in daily newspapers, the WeatherBlog has been a fun and fascinating new adventure for me. Happily, I have found the daily interaction with readers - through email, snailmail, phone calls and reader comments to the blog - to be the most fun, the most rewarding and challenging part of the assignment. (And that, at right, is where it all happens.)

Anyway, I just wanted to note the anniversary and thank The Sun for the opportunity, and the WeatherBlog's many readers for your interest, kind words and encouragement over the last five years. Please keep those notes, emails and blog questions coming.

Cheers, Frank 

(Spaarnestad Photo/Flickr.com; also, SUN PHOTOS by Frank D. Roylance)

Posted by Frank Roylance at 7:30 AM | Permalink | Comments (9)
Categories: Notes to readers
        

Tropical Storm Fred became a hurricane overnight, the second of the season, getting much better organized and doubling its top sustained winds to around 105 mph - Category 2 on the Saffir-Simpson scale. It's promising to get even stronger today.

But forecasters at the National Hurricane Center don't hold out much hope this storm will survive for long as a hurricane. It's about to run into southwesterly wind shear, drier air and cooler waters to the north. That will throw a wrench into the works, with rapid weakening to follow. And it's not likely to make it to our side of the Atlantic, either.

Fred was about 500 miles southwest of the Cape Verde Islands this morning, in the far eastern Atlantic.  

Here is the latest advisory. Here is the forecast storm track. And here is the view from space. 

Posted by Frank Roylance at 8:18 AM | Permalink | Comments (1)
Categories: Hurricanes
        

If the clouds would only part for a little while Wednesday evening, Marylanders would get a rare opportunity to watch as the International Space Station and the shuttle Discovery fly over Baltimore, one right after the other.

Discovery and its crew undocked today (Tuesday) from the space station, in preparation for their return to Earth Thursday evening. In the meantime, they will be flying more or less in tandem with the station.

It's not immediately clear which would pass over first. But here (below) is the information for the ISS flyby. My advice would be to step outside a few minutes earlier in case Discovery drops to a lower orbit and gets out in front of the station. Or, hang around for a few minutes afterwards and watch for Discovery to follow in the station's wake.

But the tracks should be the same. If you see both at the same time, Discovery will be the dimmer of the two. I've seen that twice. It's a kick.

Here's a photo of Tuesday night's pass, shot from Ontario, Canada, by Kevin Fetter. Discovery seems to have been out in front of the ISS.

For Baltimore Wednesday evening, the space station will rise above the western horizon at 8:05 p.m., moving swiftly toward the northeast like a bright, steady star. It will climb to about two-thirds of the way between the northwest horizon and the zenith (straight up) by 8:08 p.m., then head off toward the northeast, disappearing at about 8:12 p.m.

The Baltimore forecast, unfortunately, isn't very promising. But maybe the coastal storm will move far enough east to allow our skies to clear a bit. We have seen a few sunny breaks today.

Good luck, and come back here after the show and let others know what they missed.

(NASA Photo)

Posted by Frank Roylance at 4:47 PM | Permalink | Comments (11)
Categories: Sky Watching
        

Well, at least it's not hot. But there is little to cheer about in the forecast for Central Maryland as it's evolved in the last few days.

The coastal storm we've been writing about will continue to send cool, moist Atlantic air our way, with a risk of showers in the forecast for Baltimore all week. And the persistent easterly and northeasterly winds will drive ocean and bay waters ashore on the east-facing shorelines, with a risk of minor flooding as a consequence. The high tide may be exaggerated anyway because we have just passed the full moon on Friday.

The National Weather Service has posted a Coastal Flood Advisory for Anne Arundel County from 6 p.m. Tuesday night to early Wednesday morning. That will cover this evening's high tide, at around 8:40 p.m. at Annapolis. Forecasters warn:

"MINOR COASTAL FLOODING WILL BE POSSIBLE AGAIN DURING HIGH TIDES
WEDNESDAY AND THURSDAY AS LOW PRESSURE NEAR THE MOUTH OF THE CHESAPEAKE BAY
AND STRONG EASTERLY WINDS COMBINE TO PROMOTE POSITIVE TIDAL
ANOMALIES."

There are coastal advisories for the Eastern Shore, too.

Posted by Frank Roylance at 11:26 AM | Permalink | Comments (0)
Categories: Forecasts
        

That tropical depression in the far eastern Atlantic became Tropical Storm Fred overnight, with top sustained winds of 50 mph. Fred is expected to reach hurricane strength in the next few days, but steering winds in the region suggest it will not make it across the ocean to threaten the U.S. or the West Indies.

Here is the latest advisory on Fred. Here is the forecast storm track. And here is the view from orbit.

Posted by Frank Roylance at 8:55 AM | Permalink | Comments (0)
Categories: Hurricanes
        

Last week's NWS forecasts for a sunny week having been, um, revised, the coastal low that's partly responsible for the change is threatening heavy rains, coastal flooding, strong winds and rip currents from Ocean City southward to the Outer Banks.

This is not a tropical storm, and forecasters say there's only a small chance it will become one. But it is a spoiler for anyone planning to enjoy some extended post-Labor-Day beach time. The weather service says winds will be running 15 to 25 mph along the coast, with surf in the 4 to 6-foot range, and a high risk of dangerous rip currents. Here's more on that.

There are also flood watches posted Monday night and Tuesday for portions of coastal Virginia and North Carolina. Here's more on that.

In the meantime, the 7th tropical depression of the 2009 Atlantic season has formed in the far eastern Atlantic. But it does not appear likely to become a threat to the western hemisphere.  Here is the latest advisory. Here is the forecast storm track. And here is the view from orbit.

If it does make it to tropical storm force, it will become Tropical Storm Fred.

Posted by Frank Roylance at 9:15 PM | Permalink | Comments (0)
Categories: Forecasts
        

UPDATE, Monday Sept. 7: Obviously, the weather forecast has changed over the weekend. Our next best opportunity to see the ISS fly over Baltimore would be Wednesday, but the prospects aren't very good for that evening, either. We'll keep trying. Earlier post follows.

Expecting a crowd for a Labor Day barbecue? Or maybe you're going to someone else's place and you need a conversation-starter. Well, this will make you the life of the party. Amaze everyone by predicting and pointing out a bright flyby by the International Space Station. Here's how:

The ISS, with 13 spacefarers on board and still docked with the space shuttle Discovery, will be flying almost directly over Baltimore Monday evening. You will be looking at a record number of humans in space at once - 13. Skies should be clear, so you have a pretty good shot at seeing this event no matter where you are in the area.

If you're at the beach, look a little farther west. At Deep Creek lake, it will fly almost directly overhead.

From Baltimore, look to the southwest at 8:51 p.m. Watch for a very bright, steady, star-like object rising above the horizon like a swiftly moving star. If you see multiple lights, colored lights or flashing strobes, it's an airplane. Keeping looking. (NASA photo)

The ISS, moving at 17,500 mph and 216 miles up, will climb high into the sky over Baltimore, rising to 71 degrees above the northwestern horizon at 8:54 p.m., just below the bright star Vega, part of the Summer Triangle asterism. (The other points are Altair and Deneb. See if you can find them.)

From there, the $100 billion contraption will head off toward the northeast, but watch closely. About a minute after reaching its highest point in the sky, at 8:55 p.m., the station will vanish, flying into the Earth's shadow. Out of direct sunlight, it can no longer reflect the direct sunlight we need to be able to see it. The shuttle Discovery is due to return to Earth on Thursday.

Here's a bonus: That bright "star" in the southeast in the evening this month isn't a star. It's the planet Jupiter (right), currently about 381 million miles away. Take a look with a good pair of binoculars. Steady them against something solid and see if you can spot any of its four Galilean moons, tiny dots of light laid out in a line on either side of the planet. That's what Galileo saw when he discovered them 400 years ago. 

That's it. Be sure to get the kids involved. No kids? Borrow the neighbors' little angels. They can usually spot the ISS before anyone else. Who knows? Maybe one of them will be inspired and become an astronomer, or an astronaut. Or a science writer!

Anyway, enjoy, and be sure to stop back here afterwards and leave a comment. Let everyone else know what they missed.

Clear skies!

Posted by Frank Roylance at 5:17 PM | Permalink | Comments (1)
Categories: Sky Watching
        

This is why I love living in Maryland; the long, beautiful autumns and springs. Although it is nominally summertime for 18 more days, we have shifted into an early-autumn weather pattern that promises more mild and pleasant temperatures and dry air as far as the old weather-eye can see. Which is about a week.

High pressure over the Great Lakes continues to spin clockwise, pulling cool, dry air down from New England and Canada, holding hotter, more humid and rainy weather at bay well to our south and east. The weak coastal low that is sending rain bands into coastal New Jersey and Long Island won't make it here. So we're cleared for a terrific, long Labor Day holiday.

The fine weather is slated to stretch well into next week, with some moisture creeping in toward the end of the 7-day outlook.

And that outlook beats Honolulu's forecast hands down. They're looking at temperatures in the high 80s, with showers likely both day and night. We're expected to see highs mostly in the lower 80s (except for Saturday, when we could reach 87 at BWI) with no rain in sight.

Out at the beaches, temperatures will be a bit lower - near 80s degrees. But skies should stay clear. The only worry for holiday visitors will be the onshore winds, which are forecast to bring some rough surf and a moderate risk of rip currents.

In the meantime, Tropical Storm Erika has fallen apart (left), and its remnants are expected to stay well east of Maryland after the middle of next week, with no impact here.

Party on. 

(SUN PHOTO/Barbara Haddock Taylor 2008)

Posted by Frank Roylance at 9:56 AM | Permalink | Comments (2)
Categories: Forecasts
        

NASA has produced a remarkable video animation of data from Earth-observing satellites that have been monitoring the globe's "cryosphere," especially the polar ice.

You can link to it here. And here is a link to a whole bunch of nifty NASA multimedia stuff.

Also, a study funded by the National Science Foundation has found more evidence that it is the human factor, and not natural cycles, that are behind accelerating polar warming.

In fact, the arctic would likely still be in a 2,000-year-long cooling cycle if it weren't for human activity, the study found. You can read more about that here.

Posted by Frank Roylance at 5:05 PM | Permalink | Comments (1)
Categories: Cool pictures
        

Tropical Storm Erika was hanging on to its tropical storm status as it stumbled through the northern Leeward Islands Thursday morning. But only just barely.

UPDATE: 4:50 p.m.: A weakening Erika has finally been downgraded to a tropical depression, and all tropical storm watches and warnings have been discontinued. While top winds have slowed to 35 mph, heavy rains are still forecast for the region. The earlier post follows:

The slow-moving storm's top sustained winds were still around 40 mph, but those winds extended far from the storm's hard-to-pinpoint center, by as much as 175 miles in the eastern quadrant.

So, Tropical Storm Warnings remained in effect for the northern Leewards, and were extended westward to the U.S. Virgin Islands and Puerto Rico this morning. But the biggest threat from this storm for now will likely be heavy rain. Forecasters said Erika could drop 3 to 5 inches across the region, with as much as 8 inches in some places.

Erika's problem has been wind shear - high-level winds out of the southwest that are cutting off the storm's cloud tops and choking off its ability to spin up and grow. It's a factor that is especially pronounced in El Nino years like this one, and limits the number and strength of Atlantic storms. The storm also faces drier air ahead, and interference from island land masses in its path.

The storm's center Thursday morning was 200 miles east southeast of Puerto Rico, moving to the west northwest at about 8 mph.

Here is the latest advisory on Erika. Here is the forecast storm track, which shows further weakening as it moves toward the Bahamas early next week.  Here is the view from space.

In the meantime, forecasters at the National Hurricane Center have begun watching a new tropical wave that's coming off the coast of West Africa. This one looks pretty strong, but for now it is given less than a 30 percent chance of becoming a new tropical storm in the next 48 hours.

Posted by Frank Roylance at 10:55 AM | Permalink | Comments (0)
Categories: Hurricanes
        

Scientists at the National Oceanic and Atmospheric Administration say their analysis of more than a century of Atlantic hurricane data suggests that an apparent increase in the number of storms since the late 19th and early 20th century is the result of better observations and better analysis of the storms as weather science and technology have improved.

The improvements have led to the detection of more short-lived tropical systems that were missed in earlier years, the researchers concluded in a paper published in the American Meteorological Society's Journal of Climate.

Storms lasting barely a day or two that would have gone unnoticed in past decades are now being picked up by satellites and other data collections systems, and better analytical tools are defining more of them as true tropical systems.

Some examples they cite include Andrea, Chantal (forming south of Nova Scotia in the image at left), Jerry and Melissa, in 2007, and last year's Arthur and Nana.  

Although the data do reveal "substantial multi-decadal variability" in the number of tropical storms, the long-term numbers are stable. "The study provides strong evidence that there has been no systematic change in the number of north Atlantic tropical cyclones during the 20th century," said Dr. Brian Soden, a professor at the University of Miami's Rosenstiel School for Marine and Atmospheric Sciences.

The study's authors conclude that their findings are consistent with several recent global warming simulations. They note that while their work found no real increase in Atlantic storm counts, it did not address the argument by some researchers that global warming is increasing the intensity, if not the number of these storms, as well as the number that reach "major" hurricane status each year.

Here's more on the study.

Posted by Frank Roylance at 11:29 AM | Permalink | Comments (0)
Categories: Research
        

Now this is pretty darm near perfect. Canadian high pressure is parked over the Great Lakes, putting us in a nice northerly  or northeasterly flow of cool, dry air. Sunshine, low humidity and pleasant temperatures right through to the weekend.

We may see a few fair-weather clouds around as humidities slowly rise. And a coastal low could throw some clouds back our way, and maybe an overnight shower this weekend.

But all-in-all, it's relatively cool and dry right into the middle of next week, with highs no higher than the low 80s. Sweet.

Best of all, we can open the windows (well, not here at Calvert & Centre), and let the breeze sweep through.

Blankets and silent air conditioners are the rule all night long, with lows in the 50s, maybe even 40s and upper 30s in the far western counties.

Tropical Storm Erika, meanwhile, appears to have weakened some overnight, as expected. The storm is pretty badly organized for now, and is forecast to weaken further in high-level wind shear as it moves toward the Bahamas. Computer models apparently disagree over whether this storm will survive. The National Hurricane Center thinks not. Here's a snippet from this morning's NHC discussion:

"DESPITE ALL THIS
SHEAR...ALL RELIABLE GUIDANCE RESTRENGTHENS THIS SYSTEM TO NEAR
HURRICANE STRENGTH IN A FEW DAYS.  THIS REINTENSIFICATION
DOES NOT SEEM VERY LIKELY AND THE NHC FORECAST IS MUCH LOWER THAN
THE GUIDANCE.  GIVEN THE POSSIBLE SHEAR DURING THE FORECAST
PERIOD...IT WOULD NOT BE SURPRISING IF ERIKA DISSIPATED."

Erika is a minimal tropical storm now, with top sustained winds of 40 mph. It is approaching the Leeward Islands, with tropical storm warnings posted for ANTIGUA, BARBUDA, MONTSERRAT, ST. KITTS, NEVIS, ANGUILLA, ST. MAARTEN, SABA and ST. EUSTATIUS, in case you're headed down there.

Here is the latest advisory. Here is the forecast storm track. Here is the view from orbit.  

Posted by Frank Roylance at 10:45 AM | Permalink | Comments (0)
Categories: Forecasts
        

The season's fifth named storm has formed in the Atlantic Ocean, the National Hurricane Center reported Tuesday afternoon.

Tropical Storm Erika has top sustained winds of 50 mph, with slow strengthening predicted. The storm's center is 390 miles east of the northern Leeward Islands, moving toward the west northwest at 9 mph. Tropical Storm Watches have been issued for the northern Leeward Islands.

Here is the latest advisory on Erika. Here is the forecast storm track. And here is the view from orbit.

Erika seems to be following nearly the same path as Hurricanes Bill and Danny before her. Both of those storms swept north of the Bahamas and passed between the Carolina coast and Bermuda before curving north, then northeast and expiring in the North Atlantic. 

Forecasters say the storm may strengthen for a time, but faces increased wind shear in a couple of days, and that's likely to weaken Erika's power. Such high-level winds are stronger in El Nino years like this one, and are forecast to limit the number and power of this year's storms.  

But computer models disagree on how much shear will hobble Erika. Here's the hurricane center's thinking:

"THE NHC FORECAST
WILL SHOW SLOW INTENSIFICATION OVER THE FIRST COUPLE OF DAYS...THEN
WEAKENING THEREAFTER AS THE SHEAR TAKES OVER. THE NHC FORECAST WILL
BE CONSERVATIVE AT THIS TIME...BUT IT IS OF NOTE THAT ALMOST ALL OF
THE RELIABLE INTENSITY GUIDANCE SHOW ERIKA EVENTUALLY BECOMING A
HURRICANE...DESPITE THE SHEAR."

Posted by Frank Roylance at 5:12 PM | Permalink | Comments (1)
Categories: Hurricanes
        

A powerful Hurricane Jimena was bearing down on Mexico's Baja Peninsula Tuesday with top sustained winds of 145 mph, 5 to 10 inches of rain and a big storm surge. Mass evacuations were ordered and anyone with property in the resort towns should be watching events in the region with grave concern.

There should be particular concern for Mexico's poor, who will surely suffer the most from this storm. 

Here is the latest advisory on Jimena. Here is the forecast storm track. And here is the view from space.

Hurricane watches and Warnings were posted for the entire southern half of the peninsula. And the storm track appears to carry the storm's remnants, as a tropical depression, across the peninsula and the Gulf of California, into Arizona by Sunday.

The Southwestern U.S. - especially California but also central Arizona - has been unusually dry, with moderate or severe drought in portions of both states. But too much rain in too short a time may produce more problems than solutions.

The more immediate worries are for people and property in Baja California, which will feel the worst of Jimena's wind, rain and storm surge.  

Posted by Frank Roylance at 12:08 PM | Permalink | Comments (1)
Categories: Hurricanes
        

Early riser alert! Did you get up before dawn Monday morning to see the International Space Station fly nover Baltimore, only to find skies clouded over and the view impossible?

Well, here's your second chance: The ISS, with the space shuttle Discovery attached and a total of 13 humans on board for only the second time in history, will fly almost directly over Baltimore before dawn Wednesday morning.

This will be the brightest pass for at least the next 10 days, so, provided skies are clear, it should be easy to spot from any location, even downtown Baltimore. And the forecast is promising, thanks to this cool, dry Canadian air.

The catch, of course, is that you have to be up and outside by 5:30 in the morning. 

So here's the drill: Look for the ISS to appear above the northwest horizon at 5:32 a.m., as the ISS/Discovery complex passes 217 miles over Lake Michigan. It will climb through the W-shaped constellation Cassiopeia, rising nearly to the zenith (straight up) at 5:35 a.m. as it passes just north of Baltimore.

From there, the station will head off toward the southeast, past Mars and high above bright Venus rising low in the east, finally disappearing in the southeast at 5:37 a.m. as it flys over Cape May, N.J. and out over the Atlantic.

The next bright and easy-to-spot evening pass by the ISS will be next Monday evening, Sept. 7. There will be another on the 9th. Come back here for details. You can also make your own ISS flyby calculations at Heavens-Above.com

Posted by Frank Roylance at 11:27 AM | Permalink | Comments (1)
Categories: Sky Watching
        

With our reservoirs full, and a few extra bucks in our pockets thanks to cool weather in June and July, we can kiss the summer of 2009 goodbye with a smile on our faces today.

The meteorological summer ended at midnight last night, and the reality was easy to accept with that cold breeze wafting in through open windows.  Temperatures dropped to 50 degrees out on the WeatherDeck, and that extra blanket was welcome.

(Some poor toad crawled into our barbecue grille after dinner Sunday night, presumably seeking warmth from the cooling ceramic brickettes. He was still there last night when I fired it up for the salmon. It was a crispy garnish I tossed onto the lawn for whatever critters might have a taste for such things. But, I digress...)

It was 60 this morning here at Calvert and Centre streets. Out at BWI-Marshall, the official low for Baltimore was 57 degrees, just four degrees above the record low for a Sept. 1 in Baltimore, set in 1963. Here are some other low readings this morning from around the region. Plenty of 40s and at least one reading in the 30s on the map.

So how does the summer stack up?

June and July were cooler than the long-term averages for Baltimore; July especially, with an average temperature nearly 2 degrees below the norms. August warmed up, averaging 76.6 degrees, or 2.1 degrees above normal.

You can see that trend in the count of 90-degree-plus days. June had none. It was only the 6th time Baltimore's official instruments have failed to reach 90 degrees in June. It was also only the 4th time we've failed to reach 90 in May and June of the same year, and the first since 1979. The average is 7.2 days in the 90s in those two months.

July saw its first 90-degree day on the 12th, the latest date for that event since 1979. Cool nights made the news, too. The low of 58 degrees on July 14 tied the record reached in 2001 and 1895. On the 19th, the low of 57 degrees broke the 59-degree record low for the date, set in 1962.

There were four days in the 90s in July, and 6 in August as the weather finally began to heat up. That's a total of 10 for the June-August period, less than half the normal count of 25 days of 90 or more.

Steve Zubrick, science and operations officer at the NWS Sterling forecast office, says 10 days of 90-degree weather for the three-month meteorological summer ties for the eighth fewst such days since record-keeping began in 1871. All of those summers with fewer 90-plus days were a long time ago.

Summers with just 10 days of 90-plus weather occurred in four other years: 1883, 1884, 1904 and 1907.

Summers with fewer such days: 

Nine days: 1915

Eight days: 1886, 1889, 1917, 2004

Seven days:  1897, 2000.

The record for the number of 90-plus days in a Baltimore summer is 51 days, in 1988.

So we saved money on cooling, with cooling degree days ( a measure of demand for cooling energy) averaging almost 3.5 percent below the long-term average. Curiously, April had three days in the 90s, too, bringing the year's total to 13 so far.

We also recorded about 2.5 inches of surplus rain over the summer. June and August were wet, but July fell a half-inch short of the average. That all followed very wet weather in April and May, and all of it has left high water in all three of the city's reservoirs. The system is at 99.55 percent of capacity, according to the Baltimore Department of Public Works, which is extraordinary for the end of a summer that (so far) has not seen a tropical storm.

The rain totals for April through June totaled 19.74 inches, the second highest amount on record for those three months in Baltimore. The 120-year-old record is 21.69 inches, set in April-June 1889.

So, did this relatively cool, wet summer affect your outdoor activites? Is your garden out of control? Did the mosquitoes drive you crazy? Are we looking forward to cooler autumn weather? To snow? Let's hear it. 

Posted by Frank Roylance at 10:23 AM | Permalink | Comments (2)
Categories: By the numbers