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August 31, 2006

Ernesto nears hurricane strength

UPDATE: The latest advisory from the National Hurricane Center says TS Ernesto's top sustained winds have reached nearly 70 mph - 4 mph shy of becoming a Cat. 1 hurricane.

Earlier: Wow. A busy day. Tropical Storm Ernesto is continuing to strengthen out over the warm Atlantic waters off the Florida/Georgia coast. He's headed north toward landfall tonight in the Carolinas. Top sustained winds have increased to 60 mph. That's still 14 mph short of minimal hurricane strength, and the storm may never make it to that speed. But there's still time to gather up more heat energy and water vapor.

Here's the latest advisory. Here's the storm track, which hasn't changed much since yesterday. And here's the view from orbit.

The National Weather Service is still forecasting as much as 5 to 10 inches of rain for the Sterling forecast area, which includes all of Maryland west of the bay, except for Garrett County, the District, and most of northern and central Virginia. AccuWeather's new map shifts the worst of the rain to our south, leaving us with just 4 to 6 inches.

It could start falling late today, but most will arrive tomorrow morning. The worst of the accumulations will likely be on the east-facing slopes of the mountains, where rising terrain will lift and cool the air more and squeeze out more moisture. That should cancel the drought that's been building all summer. Here's today's updated Drought Monitor map.

The east winds that began blowing yesterday will persist until the storm passes by. And that will push plenty of water up into the rivers and creeks from Cecil to St. Mary's County. But this does not mean we're looking at an Isabel-scale storm surge. They're talking more like 1.5 to 2.5 feet above predicted tides. Isabel's tide was 8 feet above predictions, with wind and waves on top of that.

Unless your property is very close to sea level, or the forecast is way off base (there's a 3 to 5-foot surge forecast in the Carolinas tonight), Ernesto should not cause a major worry. Coastal flood watches are up. Keep a weather eye out.

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

August 30, 2006

5 to 10 inches of rain possible

The National Weather Service is forecasting 5 to 10 inches of rain in Maryland and northern Virginia over the next few days as the remains of Tropical Storm Ernesto move northward. That sounds wildly unlikely, given the storm's generally unimpressive performance in Florida today.

But I've spoken with David Manning, the warning coordinator at the NWS Sterling forecast office, and he insists the 5- to 10-inch prediction is not out of line. The folks at the Penn State Weather Communications office are talking about "only" 2 to 3 inches. But either way, we appear to be in for buckets of rain. You can read all about it in tomorrow's Sun.

The problem is that we're not dealing only with the tropical storm. The very moist tropical air associated with Ernesto is about to run into the cold air that settled over our region today, behind a front that pushed through overnight, dropping daytime highs today at BWI closer to 78 degrees than the 96 we saw yesterday.

Anyway, as the warm, moist tropical air from the south runs into the colder, denser air to its north, it has to rise. And as it rises, it cools. And that causes the water vapor to condense and fall as rain. Lots of rain. And when the storm's center arrives, it just brings more water to the party, and we get soaked.

The AccuWeather graphics folks have posted a sobering map showing the expected rainfall amounts and where they'll fall. We're right in the bullseye, folks. Eight to 10 inches by their lights.

With the dry weather we've had, there should be plenty of room for rain to soak into the ground and rise in the creeks without flooding. But 5 to 10 inches is a whole lot of rain.

So watch the water. Don't let the kids play in storm-swollen streams, and for pity's sake don't try to drive through flooded roadways. More people die from freshwater flooding during tropical storms  - chiefly trying to drive through high water - than from any other cause. Don't become a statistic. Or a newspaper story.

Posted by Frank Roylance at 5:36 PM | | Comments (0)
Categories: Forecasts

What about Hurricane John?

With all the fuss over Ernesto - now just a tropical depression packing a lot of rain - we've all missed Hurricane John, a 135-mph Category 4 storm that's stalking the western coast of Mexico. Although the center is forecast to remain off shore, communities along the Pacific coast are facing hurricane-force winds.

Here's the the latest advisory on John. Here's the storm track. And here's the view from space.

Posted by Frank Roylance at 1:05 PM | | Comments (0)
Categories: Hurricanes

A soaking from Ernesto

Forecasters this morning are saying Maryland's chief threat from Ernesto will be heavy rain - most of it on Friday. The storm's final track across the state will determine how much we get, and where. But predictions are running in the order of two inches or more, with 5 inches - even 10 inches in some isolated spots - possible.

That would normally bring a strong potential for flash flooding, particularly if the storm slows down or lingers over the region. But with soils parched and some streams very low in the current drought - 25 to 45 percent of the average for this time of year - it will take some serious runoff to flood them.

There's also concern about some coastal flooding along the western shore of the Chesapeake from late Thursday into Friday - especially at high tide - as the effects of several days of persistent east or northeast winds work to slosh the bay's shallow water from east to west.

With a more western track, Ernesto could also trigger some isolated tornadoes as he crosses the state from, south to north.

The good news is that we appear to be clear of the very hot weather we've seen in the last two days. It was 96 degrees yesterday at BWI-Marshall, and 97 downtown. (You can add one 90-plus day to each of the season's totals listed on today's Weather Page, in the Sun.) The cloud cover we see this morning, and the breeze off the ocean, will keep us in the 70s - maybe even upper 60s in some locations on Friday.

The other good news is that Ernesto should keep on truckin' northward, sloshing into Canada by Saturday, leaving us in a dry-out mode for the weekend. That's not to say we couldn't see some showers. But Saturday, and more especially Sunday, should bring some sunshine and drier air.

Here's the latest advisory on Ernesto. Here's the view from space. And here's a regional view.

AccuWeather offers some nice graphics.


Posted by Frank Roylance at 11:04 AM | | Comments (0)
Categories: Hurricanes

August 29, 2006

Wet days ahead

Boy, we couldn't catch a break today. Rain to our north, rain to our south, but here in Bawlmer ? Nothin'.  But don't take it too hard. It appears that Ernesto will come to our rescue. The storm's exact path remains uncertain. But the chances we'll get a soaking of some dimension seem good. Here's AccuWeather's take. And here's the NWS forecast.

And notice the high temperatures forecast for the balance of the week:  70s?  Woo Hoo! We've had precisely two days since June 25 that failed to reach 80 degrees. Now we're in line for at least five of them. This is apparently due to the advancing influence of Ernesto - more clouds and a more easterly flow off the ocean will consign these 90-plus days to the ashheap of history. Nineties in September are not unexpected, but they are mercifully few.

Posted by Frank Roylance at 6:22 PM | | Comments (2)
Categories: Hurricanes

Tornado watch for Baltimore canceled

Update: The weather service has canceled the tornado watch posted earlier today, at least on the western shore of the bay, as the band of storms moved through without affecting our area. But there was more excitement to our south, as this radar loop shows.

Earlier: The National Weather Service has issued a tornado watch for Baltimore and the surrounding counties in north-central Maryland and parts of southeastern Pennsylvania - the yellow region on this map - in effect until 8 p.m. tonight.

We don't usually think of this area as tornado country, but twisters - almost always small ones - are not really uncommon in Maryland. For an interesting, albeit incomplete accounting of past Maryland tornadoes, click here.  The biggest tornado in recent memory was the F4 La Plata twister that struck Charles County in April 2002. For a detailed tour of the damage, click here.

Posted by Frank Roylance at 2:35 PM | | Comments (0)
Categories: Tornadoes

Ernesto moves on S. Florida

Tropical Storm Ernesto - a 45 mph storm that was a hurricane for only a short while before running aground on the islands of Hispaniola and Cuba, and which would hardly have been noticed before the last few years of repeated damage and deaths in the U.S. from tropical systems - appeared to be growing in size and moving on South Florida today. More importantly for us, the forecast storm track continues to show the storm tracking north from Florida, back over warm Atlantic waters for potential strengthening, then overland toward western Maryland.

Depending on the path Ernesto finally chooses, we could be in for a very wet Labor Day weekend. Maryland's state and local emergency managers convened today by telephone to be briefed by the weather service on the storm's progress and potential for causing problems here. Another update is planned for tomorrow morning.

Hurricane watches are posted for parts of the southeast coast of Florida and Lake Okeechobee. Tropical storm warnings and watches are posted farther north on both coasts - and as far as Georgia on the Atlantic side.

The storm may not look like much, but there is a chance for isolated tornadoes in Florida, and as much as 15 inches of rain. That's nothing to sneeze at.

Here is the latest advisory. Here is the forecast storm track and map of the warned areas. And here is the view from space. Here is the weather in Key West. And here is AccuWeather's take on what's in store for us.

Posted by Frank Roylance at 12:49 PM | | Comments (0)
Categories: Hurricanes

Rain, storms, flash floods ...

A low pressure system pushing through from the Ohio Valley, coupled with the approach of whatever remains of Tropical Storm Ernesto by week's end, spell a lot of wet weather ahead for the Baltimore region. We will likely see some thunderstorms this afternoon and evening. Stoked by solar heating through breaks in the clouds, some of them could become severe, with high winds and heavy rains that could trigger some local flooding.

The arrival of the tropical moisture from Ernesto will mean more rain toward the weekend, but at least temperatures will ease later this week - with highs in the 70s. Looks like our drought is about to be washed away.

Here are the current advisories from the forecasters at Sterling. Here is the forecast for BWI-Marshall.

And here's a bit of the forecasters' thinking (with my edits for clarity) about this weekend, and Ernesto:

ALSO...REDUCED HIGH TEMPS (forecasts) 1-2 DEG F FROM (previous estimates) THU-SAT WITH

Posted by Frank Roylance at 12:32 PM | | Comments (0)
Categories: Forecasts

August 28, 2006

New track shows Ernesto west of Bay

The center of the latest forecast storm tracks for Tropical Storm Ernesto has the system moving along a path to the west of this morning's plots. It is now expected to move northward from Florida, and onshore, passing through the Carolinas, and Virginia, then west of the Chesapeake Bay by Saturday.

By that time, forecasters say, the storm will have been weakened to no more than a tropical depression. But the track west of the bay means more rain - hopefully not too much - for drought-parched Central Maryland (we need slow, steady rain, not torrents and stream flooding) and perhaps a greater risk of storm surge flooding in the Chesapeake.

It will all hinge on the storm's final path, and remaining strength and winds, of course. But tropical storm systems spin counter-clockwise. That means the winds on the east side of the storm will be blowing from the south or southeast. With western tracks across Maryland, that drives water up the Bay, preventing it from sloshing back out of the estuary at low tide. The right combination of wind and high tide timing can mean storm surge flooding along the bay shore.

Here's the latest from the Hurricane Center. Here's the view from orbit.

Posted by Frank Roylance at 5:16 PM | | Comments (0)
Categories: Hurricanes

Best rain chances Tuesday

That cold, or "cool" front that's been hanging out just to our north seems likely to drift south in the next day or two, and forecasters say that - along with a shot of low pressure from the southwest - hold our best chances for some significant rain tonight or tomorrow.  Here's the forecast for BWI.

The folks at Sterling say we could see up to three-quarters of an inch in some spots tomorrow. There are slighter chances for less than that this afternoon and evening, and for later in the week. But tomorrow looks like our best shot.

Whatever comes along, we need it badly. The airport saw a few drops last night - 0.01 inch. And I recorded another 0.02 on the WeatherDeck overnight, on top of the 0.21 inch that fell early Sunday. But the official measurement at BWI-Marshall still shows is off nearly 2 inches this month, on top of another 2-inch deficit in July.

A big shot of rain from whatever remains of Tropical Storm Ernesto by week's end would be very welcome. That's often how these late-summer droughts end.

Posted by Frank Roylance at 12:02 PM | | Comments (0)
Categories: Forecasts

Minor bay flooding possible

Persistent southeast winds up the bay have prevented some water from exiting at low tide. That, combined with an approaching low pressure system, has prompted forecasters to advise Marylanders to watch for unusually high tides today and tonight - 1 to 2 feet above predicted levels.

Here is how the current tides are behaving. (Just click on Maryland, and choose your favorite tide gauge location.)

Posted by Frank Roylance at 11:47 AM | | Comments (0)
Categories: Flooding

Ernesto shifts east toward Carolinas

Hurricane forecasters have shifted their predictions for Tropical Storm Ernesto's future farther to the east. Instead of crossing Cuba and charging into the Gulf of Mexico, the center of the current predicted storm tracks leads up the Florida peninsula, off the Georgia coast and on toward Cape Hatteras by Saturday. Here's the current track forecast.  Here's AccuWeather's take on the storm.

The shift away from the Gulf and its oil rigs has already reduced oil prices and given a boost to the stock market.

This is also a positive forecast for Maryland. Tropical storms that veer offshore from the Outer Banks, as this one, for now, is expected to do, do not pose wind or storm surge worries for the Delmarva beaches or the Chesapeake. It's the storms that come ashore in the Carolinas, and charge up the western shore of the bay that we worry most about.

The new track will also spare the northern Gulf Coast, which is still recovering from last year's storms. And it will avert the potential strengthening of the storm over the warm Gulf waters.

But it will mean a tough week for Florida, where many residents  - those who haven't already cashed out and found new homes elsewhere - are still recovering from the four storms of 2004, and others last year.

The storm is currently making landfall in eastern Cuba. Tropical storm warnings are already up there, and hurricane watches are posted for parts of Florida and the Bahamas.

Here is the latest advisory on Ernesto. And there is the view from orbit. Here's another shot of the storm as it approached Haiti over the weekend.

And finally, in the event that you have not yet been sufficiently inundated by year-after Katrina information, here's NASA's retrospective on the worst hurricane ever to strike the U.S.

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

August 27, 2006

Ernesto intensifies, threatens Haiti

Tropical Storm Ernesto is a growing threat to the Caribbean, the Gulf and probably, late in the week, to the United States. New Orleans seems likely to be spared. But Florida, which took such a battering in 2004 and again last year, looks like the most likely U.S. target. In the meantime, hurricane watches and warnings are posted for parts of the Dominican Republic, Haiti, Cuba, Jamaica and the Cayman Islands.

Top sustained winds are already at 70 mph - close to hurricane force. Ernesto is expected to become a hurricane later this morning, the first of the season. Some islands could see 6 to 12 inches of rain. 

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

Posted by Frank Roylance at 7:47 AM | | Comments (0)

Zowie! Rain!

Woke up at 4-something. Thought I heard rain on the roof. But I dismissed it as fan noise. But this morning the instruments on the WeatherDeck here in Cockeysville show 0.21 inch of rain fell between 4 and 4:30 a.m.  It came down as hard as 1.66-inch an hour at one point. It's only the second measurable rainfall here since Aug. 10.

Alas, the station at BWI-Marshall saw nothing. Ditto for Reagan National in Washington, Martin Airport in Essex and the Inner Harbor. Dulles, out at Sterling, Va., got a mere 0.01 inch. Frederick saw 0.11.  Hardly enough to wet your whistle. Wilmington, Del., seems to be the winner this morning, with just over half an inch by 6 a.m.

It's hardly the end of the drought up here. That may take a swipe by whatever is left of TS Ernesto. But at least it's water on the garden that didn't come from a hose. Anybody else out there get some rain this morning?

Posted by Frank Roylance at 7:33 AM | | Comments (0)
Categories: Drought

August 25, 2006

Max Mayfield is retiring from NHC

Max Mayfield, 57, director of the National Hurricane Center since 2000 and familiar to millions as the unflappable, white-haired, TV face of the federal forecasting agency, says he'll retire soon. Max says he needs a rest. We don't blame him. It's been a tough couple of years in the hurricane biz. Here's the CNN story.

Posted by Frank Roylance at 6:01 PM | | Comments (0)
Categories: Hurricanes

Season's 5th tropical storm is born

TD5 is now the fifth tropical storm of the season. Ernesto is churning across the eastern Caribbean, headed, apparently, for the Gulf of Mexico. He's expected to become a hurricane by Monday afternoon. Here's the latest advisory. Here's the storm track forecast. And here's the view from space.

Posted by Frank Roylance at 5:23 PM | | Comments (0)
Categories: Hurricanes

TD5 could be a storm by today

Tropical Depression 5 seems destined to become the season's fifth tropical storm - Ernesto - sometime today. Now brewing in the southeastern Caribbean, the bad weather appears to be getting better organized, and could become the season's first hurricane in a few more days.

And it seems to have designs on the Gulf of Mexico, which has very warm sea surface temperatures - gasoline for hurricanes. The only way out of the Gulf, of course, is to crash ashore somewhere in Mexico or the U.S. Unless the storm fizzles, we will be reading about this one for the next week or more.

Here is the latest advisory. Here is the forecast storm track. And here is the view from space. And here is AccuWeather's take on the storm's future.

Posted by Frank Roylance at 10:44 AM | | Comments (1)
Categories: Hurricanes

August 24, 2006

Ask Mr. WeatherBlogger: Sun gets in your eyes

Here's an odd one. "Dee" writes from a Baltimore County Public Library: "On the afternoon of Sept. 12, I will be flying from BWI to Salt Lake City. I want to sit where the sun will not be in my eyes. The location of sunsets in the continental U.S., in different seasons, has always puzzled me, and probably always will. Is there a rule of thumb?"

Let’s see, Dee. You could change your reservation and fly after sunset (7:19 on the 12th). You could fly east, around the planet, and face the east for the entire flight and miss all the sunsets. You could, of course, pull the shade. Problem solved.

But, if you're like me, you probably like to look out the window at the countryside drifting by. So, here are some thoughts.

You'll be flying almost exactly due west. That means the passenger windows will face either north or south.

Sunsets (and sunrises) during late summer and fall are moving slightly farther south each evening, from their farthest north at the summer solstice in June, to their farthest south at the winter solstice in December.

At the time of the Autumnal Equinox (Sept. 23 this year), the sun rises due east and sets due west. If you were to fly on that date, the sunset would be in the pilots' eyes, but passengers looking north or south wouldn't have a problem. (This assumes a flight plan taking you straight west. Course changes, turns to avoid thunderstorms and maneuvers during climb and descent mean all bets are off. You're on your own.)

But you're flying on the 12th, or 11 days before the equinox. That means sunset will occur a bit north of due west. If you're on the right side of the airplane, you might get some sun in your eyes just at sunset.

On the other hand, you'll probably spend several hours on the plane before sunset. If sunlight is bothersome to you, that presents another problem.

Hypothetically, if you were flying west along the equator, on the equinox (Sept. 23), the sun's path during the afternoon would be from directly overhead at noon, to due west at sunset. You'd never see the sun from a passenger's seat. Eleven days before the equinox, however, the sun, at the equator, would be slightly north of straight up. So, the right side of the plane would be sunnier throughout the flight.

But you'll be flying at a latitude of, roughly, 40 degrees north. That means the sun's path through the sky will be along a path well south of straight up. That means the seats on the left (south-facing) side of the plane will be sunny throughout the flight, until shortly before sunset, when sol will cross in front of the plane and touch down at the horizon slightly north of due west.

The bottom line: Sit anywhere on the right side of the plane until perhaps 30 minutes before sunset. Then, when somebody gets up from a left-hand window seat to use the rest room, steal their seat. Or, rather than raise a ruckus and get yourself locked up, you could a) make your reservation for a right-hand seat, and then pull the shade at sunset; or b) if it's only the sunset that offends you, get a left-hand seat, enjoy the afternoon sunshine and let the sunset fall on those on the right side of the airplane.

Posted by Frank Roylance at 1:09 PM | | Comments (2)
Categories: Ask Mr. Weatherblogger

A splash, maybe

Forecasters say Central Maryland could see a thunderstorm or two this afternoon. It's only a 40 percent chance. Not everyone will see it. And even if we do, they say it won't amount to more than a quarter inch. 

But we'll take what we can get. Although amounts vary by location, the official instruments at BWI-Marshall have seen just two significant rain events this month: nearly an inch (0.95 inch) on Aug. 7, and almost a half-inch (0.47 inch) on the 20th. July, too, was very dry.

So, we're parched. The new Drought Monitor map, out this morning, shows nearly all of Maryland - except for far western Garrett County, experiencing at least "abnormally dry" conditions - part of a broad sweep of dry weather that extends from the Deep South to southeastern Pennsylvania and southern New Jersey. And the central part of Maryland has fallen in the past week into "moderate drought" conditions affecting chiefly agriculture (rather than water supplies) for the second time since May.

Posted by Frank Roylance at 11:07 AM | | Comments (0)
Categories: Forecasts

Tropics begin to stir

It looks like Tropical Storm Debbie will continue spinning far out over the Atlantic. It's highest sustained winds are now 50 mph. But Debby appears to be doomed to wander the Atlantic, and doesn't seem likely to become a threat to land.

But we're now in what is statistically the most active period of the Atlantic hurricane season, and trouble finally appears to be stirring near the Windward Islands.

Forecasters at the National Hurricane Center are watching a tropical wave that is approaching the islands, near the north coast of South America. It is likely to become a tropical storm shortly, and perhaps the season's first hurricane. Here is this morning's Tropical Weather Outlook:


Here is what it looks like from orbit.

As for Debby, here's the latest advisory. Here's the forecast track. And here's the satellite view.

Posted by Frank Roylance at 10:47 AM | | Comments (1)
Categories: Hurricanes

August 22, 2006

Max Mayfield and Katrina 2

The director of the National Hurricane Center says the U.S. is setting itself up for a hurricane disaster even worse than Katrina. Here's the link to a Reuters interview.

Posted by Frank Roylance at 9:57 AM | | Comments (0)
Categories: Hurricanes

August 21, 2006

New tropical depression forms

Tropical Depression Four has formed near the Cape Verde Islands in the far eastern Atlantic Ocean. Tropical storm warnings have been issued for the islands. The storm poses no immediate threat to land in the Western Hemisphere, but forecasters will be watching it. It is heading west northwest, with top sustained winds of 35 mph.

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

Posted by Frank Roylance at 7:11 PM | | Comments (0)
Categories: Hurricanes

Sky show for early risers

Look for an interesting conjunction of moon and planets low in the eastern sky Tuesday morning. Maryland skies should be unusually clear and dry for this event. It's our heads and eyes that may be foggy an hour BEFORE sunrise.

For the sleepless, or the dog owners among us, try this:  Find a place with a low horizon in the east. An hour or so BEFORE sunrise (which occurs at 6:26 a.m. Tuesday for Baltimore) look for bright Venus a bit less than 10 degrees above the horizon. Zig down and to the left to find a slim crescent moon. Then, zag down and right to find Saturn. And finally zig left again and down to find dim Mercury.  The link above includes a sky map.Binoculars will help with the dimmer planets.

Even if it's too hazy, or your view too obscured to see Saturn or Mercury, the sight of Venus and the slender moon will make the lost sleep worthwhile. Or not. You be the judge. And leave a comment here to let us know if you saw anything. It helps me to know if anyone bothers to look at this morning stuff.

Posted by Frank Roylance at 6:21 PM | | Comments (3)
Categories: Sky Watching

Wild tornado video

Want to see the weirdest, skinniest tornado ever? Click here for a link to the video. The twister was taped by a homeowner in Colorado, who provides a running commentary as she calls family members to describe it. She probably didn't expect her narration, or her baby's whining, to be carried worldwide via the Web. "It is really cool. I'm videotapin' it," she says. Her 5 minutes of fame.

Posted by Frank Roylance at 2:35 PM | | Comments (1)
Categories: Tornadoes

Gorgeous, unless you're a plant

After a very hot and muggy weekend, we've graduated to a new air mass. High pressure has settled into the region and the forecast looks clear and sunny, but not too hot or humid, for the balance of the week.

This is August at its best for Baltimore, except for the fact that we are getting very short of rain. Visitors to Harborplace this weekend noticed how brown Federal Hill Park has become. But then so have lawns and gardens all across the region. We did get some brief showers as the cool front moved through on Sunday. BWI saw 0.06 inch. We had 0.04 inch on the WeatherDeck in Cockeysville. Other locations well to our north saw much more.

The federal Drought Monitor map issued last Thursday morning shows that the "abnormally dry" region that had retreated south after June's heavy rains has crept back into Central Maryland.

The last significant rain at BWI was the 0.95 inch that fell two weeks ago on Aug. 7. Since then the airport has seen just seven hundredths of an inch. We're now 1.38 inches short for the month. And that comes on top of the 2-inch deficit in July. Although many spots have seen more in spotty storms, the airport has had just two rain events since July 1 that amounted to more than two-tenths of an inch. Those fell on July 5-6, and Aug. 7.

So, it's not officially a drought yet. But it's sure starting to look like one. It's the sort of summer dry spell that is frequently relieved by the remnants of a late-summer tropical storm. But there are none of those on the radar screen yet, either.

The best the National Hurricane Center has to offer this morning is a "vigorous" tropical wave off the coast of Africa that seems promising to forecasters. It will take a week or more before we know whether that will amount to anything. Here's a Reuters article on this late-starting season.

Nobody wants a storm that endangers lives and properety, of course. But something that packs some substantial rains would sure be welcome in these parts.

Posted by Frank Roylance at 12:02 PM | | Comments (0)
Categories: Forecasts

August 18, 2006

Floods in the news

First heat, now floods. Heavy rain and high water are making news in all kinds of places around the world. Here is a sampling from Ethiopia, Vietnam, Pakistan, Arizona, and North Korea.

Thankfully, the forecast here looks just fine. We continue to enjoy some of the nicest weather of the summer - 80s, dry and sunny. It will be muggier, and we could get a little rain either day over the weekend as a new front comes through, but frankly we could use the rain. And beyond that it looks like more of the same. Sunny, warm, clear and dry. Perfect.

Headed for the beach?  Looks like a slightly higher chance of some showers out there. But all in all, not bad.

Posted by Frank Roylance at 3:51 PM | | Comments (0)

A bit of weather humor

As someone who favors print journalism, in part, because it gives me the opportunity to avoid embarrassment by fixing a mistake and polishing a story before it goes public, I have huge admiration for the TV types who somehow manage (usually) to spit out a coherent report, live from the scene, or the set, without saying something dopey or becoming totally tongue-tied.

Well, it takes practice, and sometimes it all just goes wrong. AccuWeather's Web site offers a bunch of out-takes from their weather Web casts, as well as some horsing around on the set by a crew of young weather-casters. They're all pretty funny, a few are hilarious. Fair warning: some are also a bit off-color, but they're labeled as such.

I haven't found a way to get there directly. But try this: Click here for the AccuWeather main page. Then look for "Related links," just below the top story, and click on whatever "video" link is offered. That will take you to that video clip, but you should see an index to other stories just below it. Scroll to "Bloopers," and click. There's also one called "On a lighter note." Both are worth a look, even though you may have to wait out a Holiday Inn ad.

Posted by Frank Roylance at 11:46 AM | | Comments (0)
Categories: Notes to readers

The little storm that couldn't

In a more hospitable year for hurricane formation, the little storm stewing off the coast of northeast Florida might have become a grown-up tropical storm, or even a hurricane. But not this year.

Instead, the disturbance formed, rained, and meandered a bit off the South Carolina/Georgia coast. And it continues to give the meteorologists fits as they sit on pins and needles waiting to see what tests their first post-Katrina hurricane season will send them. The computer models have offered up possible storm tracks that look like a Daddy Long-Legs - headed off in any and all directions. For now, the storm is drifting southwestward toward North Florida.

Forecasters say upper-level winds have sheared off the little puffer's energy, leaving it to fuss and fume in the Atlantic, tossing showers and waves ashore without ever growing up. Poor thing has never gotten a name, or even a number as a tropical disturbance.

Here's how it looks from orbit.

Here's this morning's discussion:


Posted by Frank Roylance at 11:00 AM | | Comments (0)
Categories: Hurricanes

August 17, 2006

Conservation saved millions in heat wave

The PJM Interconnection - the outfit up in Valley Forge, Pa. that manages the generation and distribution of electrical power for 12 states (including Maryland) and the District of Columbia, says consumers heeded their call to conserve power during the recent heat wave, and collectively saved wholesale customers more than $650 million.

Power consumption during the hot weather peaked at a record 144,796 megawatts on Aug. 2. On that day, PJM officials report, voluntary reductions in power usage led allowed utilities to avoid switching on their most expensive generators. That enabled price cuts on the spot market totaling more than $230 million. The benefit fell mostly to big wholesale consumers, such as BGE, in the form of direct payments for the power they saved.

One hopes that retail buyers - like you and me - will enjoy some trickle-down effects in the form of lower monthly bills in the short term, and lower rates in the long term.

Posted by Frank Roylance at 1:39 PM | | Comments (1)
Categories: Events

Clear skies for Space Station tonight

This evening offers one of the summer's best, and most convenient opportunities to see the International Space Station from Baltimore. The ISS will soar northeastward, from New Orleans to Nova Scotia, passing directly over Baltimore shortly after 9:15 p.m.

The forecast looks very promising: mostly clear, dry air, and a nice, balmy evening ideal for stretching out under the stars and watching for meteors (Did you miss the Perseid meteor shower last week? Here's a photo gallery), passing satellites and the $100 billion space station. The station should be easy to see if skies are clear, even in urban lighting. Take the kids. Or the neighbor's kids if you've run out. They're often quicker to spot the moving space station among the stationary stars. No binoculars or other equipment are needed. Here are the specifics:

The ISS will appear first above the southwestern horizon at about 9:15 p.m. Look for a bright "star" moving briskly toward the northeast. If it has multiple lights, colored lights, or a flashing white strobe, it's an airplane. Keep looking. Look for it near the planet Jupiter, which will be the brightest fixed object low in the southwest after 9 p.m.

By 9:17 p.m., the station will be directly overhead - about 215 miles above Baltimore, nearly as far straight up as North Carolina's Outer Banks are to our south. What you're seeing is sunlight reflected off the station's modules and solar panels. Sometimes the light has a slightly coppery hue, the color of the solar collectors. The whole package is moving at about 17,500 mph, circling the planet once every 90 minutes or so.

There are three crew members on board - an American, a European and a Russian.

Zipping on toward the northeast, the station will fly past Vega and then Deneb, two of the bright stars of the Summer Triangle. Vega is the bright star just east of the zenith (directly overhead). The ISS will fade away just above the northeast horizon as it moves into the Earth's shadow - nightime for those on board.

For more flyover predictions for your location, visit

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

August 16, 2006

Insurors to storm victims: get a mop

Hurricane Katrina victims who argued that the storm surge that ruined their home was caused by storm winds have been dealt a setback by a federal judge in Mississippi. He ruled that their homeowners' policy covered wind damage, but not water damage caused by a storm surge driven by the wind. It's a cruel twist in the insurance biz that Tropical Storm isabel's victims know well. Here's the story.

Posted by Frank Roylance at 3:47 PM | | Comments (0)
Categories: Events

Hurricane nursery warms up

The tropics are still quiet, and we have yet to see this season's first hurricane - only three tropical storms so far. But satellite imagery shows that the ocean waters where hurricanes are born have heated up since August 1. If winds become favorable, we should start to see some action. We are now entering what is normally the busiest portion of the hurricane season.

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

August 15, 2006

How hot has it been?

The summer isn't over yet, but already the weather statisticians have been crunching the numbers. The Summer of 2006 already ranks among the 25 hottest on record in the region. And the hottest of all weren't all that long ago. Here's a recent rundown by the folks out at Sterling.

Posted by Frank Roylance at 2:29 PM | | Comments (0)
Categories: By the numbers

This, too, shall pass

We're back, just in time to straighten out the forecast. The clouds I see over the State Penitentiary this morning mark the approach of a weak cold front from the northwest. We may get some showers, or even a stray thunder shower out of it. But mostly it will just scoot through, and usher in some clearer, slightly drier weather for the next few days. It won't exactly be cooler. The forecast calls for highs in the mid- to upper-80s. That's a tad above the 85-degree norm for this time of year. And it may feel a bit more humid than last week's perfection. But it's still mid-August. It's fine.

Here's a nice shot of the East Coast weather, snapped yesterday by NASA's Terra Earth Observing satellite. Click on the photo, then enlarge it by holding your cursor over the image, and clicking on the exlarger button on the lower right corner.

Still nothing much brewing in the tropics. The National Hurricane Center is watching a few spots - one on each side of the Florida peninsula, and another way out east near the Cape Verde Islands. But neither one poses a threat for now. 

Posted by Frank Roylance at 11:15 AM | | Comments (0)
Categories: Forecasts

August 9, 2006

A perfect weekend

The back-to-school sales are already in full swing. I even got a Halloween catalog in the mail the other day. But there's no reason to rush the seasons. This weekend is shaping up to be one of the best of the summer. Savor it.

The forecast promises sunny days and clear, starry nights. Highs should hold firmly in the 80s. And the overnight lows - in the 60s - will be great for sleeping. Open the windows, shut off the fans and air conditioners and let the electric meter slow to a crawl.

The beach weather looks terrific, too. Let the kids enjoy it. School's just around the corner.

With the weather under control, the WeatherBlog will be idle for a few days while my favorite teacher and I take a few days of R&R before school bells ring. Don't forget the sun block. 

Posted by Frank Roylance at 8:01 PM | | Comments (0)
Categories: Forecasts

July was 2nd-hottest on record

The National Oceanic and Atmospheric Administration reports that July 2006 was the second-hottest July on record for the lower 48 states. And, the first seven months of the year were the warmest January-to-July period since record-keeping began in 1895. Here's the skinny.

Posted by Frank Roylance at 12:09 PM | | Comments (0)
Categories: By the numbers

Government forecasters trim hurricane forecast

Following in the steps of Colorado State University hurricane forecasters Phil Klotzbach and William Gray, the National Hurricane Center has revised - downward - its predictions for the balance of this year's Atlantic Hurricane Season. Here's the link to their report. It's not the fact that we've seen just three tropical storms so far (and no hurricanes), they say. As Klotzbach and Gray, too, made clear, it's changes in the wind, water and atmospheric conditions that are slowing the development of the tropical cyclones. Even so, both camps are still predicting a busier-than-average season.

Posted by Frank Roylance at 12:04 PM | | Comments (0)

Clear skies for Perseid meteors

The forecast looks terrific for Friday night's debut of the annual Perseid Meteor Shower. Only the nearly-full moon will diminish the show this year.

This annual event typically produces up to 100 "shooting stars" per hour. It's not the busiest of the annual meteor showers, but it is the most popular, thanks to the mild weather and the number of people on vacation who can afford to stay up late (or get up early) to watch it.

The fly in the ointment this year is the moon. It will be just two days past full, rising about 9:36 p.m. and staying up for the rest of the night. The resulting glare will wash out most of the dimmer meteors, although the bigger, brighter ones will still be visible.

If nothing else, it will be a great night to be out under the stars. The air should be clear and relatively dry. From a dark location, the Milky Way will be in full glory. Jupiter is gleaming - the brightest star-like object in the southern sky. (Put some binoculars on it and see if you can spot its four largest moons, lined up in a row on either side of the planet.) If you're up early, you can watch for Venus and Mercury to rise above the eastern horizon after about 4:30 a.m.

There's also this slim, but very cool possibility: NASA is reminding meteor-watchers that in the brief time between sunset and moons rise (between, say 8:30 p.m. and 10 p.m.), we can expect to see the very first of the Perseid meteors to come into the atmosphere at very low angles - skipping over the outer atmosphere like pebbles skipping across a pond instead of plunging straight in.  These "Earth-grazing Perseids" are rare, but they can put on quite a show.

So, pick out the darkest location you can find. Set out a lawn chair or a blanket in a spot where the moon will be behind you or behind a tree or building. Relax, let your eyes adjust to the dark, and watch for the Perseids.

They will appear to be coming from the Constellation Perseus (just below the "W"-shaped constellation Cassiopeia), which rises in the northeast after sunset. (That's because that's the direction the Earth is moving along its orbit, and therefore where the atmosphere first strikes the dust particles.) But you will be able to see them zipping by almost anywhere in the sky.

What you're seeing are bits of dust scattered along the trail of the Comet Swift-Tuttle, which returns to the inner solar system once every 130 years, the last time in 1992. The size of sand grains or peas, they're circling the sun along the comet's orbital pathway. We see them because, in its annual trip around the sun, the Earth runs through the dust trail like a car through a swarm of insects. As the Earth's atmosphere encounters them, the particles plunge into the air at 36 miles per second, heating the air molecules around them, vaporizing, and producing the brief glow we see as a "shooting star."

Good hunting! Oh, and if you miss the shower's peak on Friday/Saturday, try again the next night. The activity will taper off a bit each night for about two weeks.

Posted by Frank Roylance at 11:16 AM | | Comments (0)
Categories: Sky Watching

August 8, 2006

We almost hit 90 at BWI

But not quite. Looks like we've passed the peak heat of the day without touching 90 degrees today - for the first time since July 27. So the 90-plus streak stops at 12 days. But it was close. The reading was 89 degrees at BWI-Marshall at 2:36 p.m.  It was 88 at the Science Center downtown. Normal for this date at BWI is 86 degrees.

But while it was pretty warm, the humidities have fallen sharply. The dew points have been falling all day, in fact, from a muggy 73 degrees at midnight last night, to a clean 59 degrees this afternoon. With that kind of dry air, if I may put it indelicately, sweat evaporates, and we can cool ourselves handily in 89-degree air, thank you.

On the other hand, it's been snowing in South Africa, where it's winter. And bad weather is pummeling Japan, Pakistan, China, Ethiopia and India.

Posted by Frank Roylance at 4:54 PM | | Comments (0)
Categories: By the numbers

Storms usher in fine weather

The thunderstorms that swept through much of the region late yesterday not only provided a needed drink for parched lawns and gardens, it also raised the curtain on what promises to be a fine stretch of summer weather across the region.

Showers at BWI-Marshall left 0.77 inch of rain - a tenth of an inch more than I registered on the WeatherDeck in Cockeysville. That single observation would have to be listed as one bit of evidence against the theory, discussed in recent posts, that BWI gets less rain than the higher inland terrain. The Inner Harbor recorded 0.3 inch.

The rain, and the front it ushered in, cut the temperatures at BWI from an afternoon high of 95 degrees, to 78 degrees in an hour. The overnight low was 72, but we can look forward to even cooler nights for the rest of this week. The forecast calls for a low of 60 degrees at BWI tonight (the first time it's been that cool since July 8), followed by lows in 60s through the weekend.

So, open those windows, shut off the AC, save a few bucks and listen to the dog-day cicadas chattering in the trees (or the neighbors yammering into the night, depending on where you live). Here's a link to Mike Raupp's Bug of the Week post on these bugs.

The daytime highs should hold near the seasonal averages (86 degrees) today and through the weekend. And humidities will be much lower than in recent weeks. This relief arrives after 12 straight days of 90-degree-plus weather, which began July 27. Through Monday, we had 14 days in a row of above-average daily temperatures.

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

Heat stroke: from the cutting room floor

Sometimes newspaper stories are the product of a collaboration of reporters. One will take the lead reporting and writing role, while others pursue other components of the story. At some point during the afternoon, the contributors file their "inserts" or "feeds" to the lead reporter, who assembles it all into a (hopefully) coherent whole. If the contribution is substantial, they'll get a "shared" byline with the lead writer (whose name goes first at the top of the story). If it's less substantial, the contributor will get a "contributor line" - a mention, at the bottom of the story.

And sometimes the contributing reporter files so much material that much, or most of it never makes it into the story, and it dies on "the cutting room floor," or in our case, in the computer system, to be purged a few days later and sent into digital oblivion.

Today's P. 1 story by Julie Scharper, on the heat-related death of a Baltimore man, is a case in point. My job was to find out why people die from heat exposure, and how it's diagnosed. Tight space, and the fact that I habitually report and write too much, led most of what I came up with yesterday to be cut from the final version of Julie's story. That's fine. It happens a lot.

But since it's weather-related, and may help readers understand why it's so important to check on the elderly and other vulnerable individuals during extreme hot weather (and because I took a great deal of time from Dr. Thomas Kirsch, the director of operations at Johns Hopkins Emergency Medicine to gather the information), I thought I'd resurrect the cuts and offer them here:

Humans have evolved a variety of mechanisms to cool things down if we can’t escape our overheated environment.

The tiny capillaries in our skin open up, bringing more blood to the surface, where it can radiate and dissipate body heat into the air. But the most efficient mechanism is the evaporation of sweat.

As temperatures rise, our sweat glands start moving water — and heat — to the surface. It evaporates, and the body cools.

High relative humidities – above about 75 percent — can make that evaporation impossible.

Healthy people who engage in strenuous activity in the extreme heat and humidity may also drive up their body temperature faster than their bodies cool off.

But the most vulnerable are the very young, the elderly, the sick, the obese and people on certain medications, Kirsch said. Abnormal skin, or medicine that inhibits sweating can get people into trouble. So can certain heart medications.

The increased blood volume that must flow to the skin to cool the body puts a big extra load on a weakened heart. And some cardiac drugs may make it even harder for the heart to keep up.

If the body generates heat faster that it can shed it, the core body temperature slowly rises. Normal metabolic processes quit working, and organs begin to fail.

One of the key danger signs is a change in a victim’s mental status – lethargy, confusion or coma, Kirsch said. "Anyone who comes in [to the ER] during a heat wave acting confused, a diagnosis of acute hyperthermia is way up on our list."

That, plus high body core temperatures trigger immediate intervention.

"Cooling, as fast as possible," Kirsch said. That can mean cooling blankets, or ice packs in the armpits or groin.

"But evaporation is still the best way to conduct heat away from the body," he said. "We strip them down, put fans in the room and have people continually spray water over them … just a cleaning bottle with water."

It’s often not enough, he said. Studies have found that one in five patients who arrive at the ER with body core temperatures of 104 or higher will die. And some of those who survive leave with permanent brain damage, or in a coma.

The lessons are clear, Kirsch said. "When the [outside] temperature goes up like that you have got to get out of the heat."

"If anyone has an elderly relative, they should clearly, during a heat wave, check on them, and try their best to get them out of the hot environment. And if there are any signs of confusion, they need to call 911."

Posted by Frank Roylance at 9:07 AM | | Comments (1)
Categories: Events

August 7, 2006

Gang of Three threatens Asia

Residents of coastal China have taken a pounding this summer from typhoons crashing ashore from the Pacific Ocean. At least six have struck the country, killing more than 1,000 people, destroying more than a half-million homes, 3 million hectares of crops and causing more than $9 billion in economic losses. More than a million people were evacuated in a single storm.

Now, three more of these Pacific hurricanes are on the scope. Here's an astonishing image, snapped today by NASA's Aqua Earth-Observing satellite. Three typhoons captured by a single pass of the orbiting cameras. (The "sunglint" label marks the sun's reflection off the ocean's surface.)

Fortunately for the Chinese, only two of these storms appear headed for China. Maria looks like it's going to do its worst in Japan. Here are the forecast tracks for typhoons Bopha, Maria and Saomai.

India, too, is grappling with bad weather as monsoon flooding wreaks havoc. More here.

Posted by Frank Roylance at 6:31 PM | | Comments (0)
Categories: Hurricanes

Why so dry at BWI?

The WeatherBlog continues to receive quite a number of notes and queries regarding what looks to some to be a skewed - or at least curious - lack of precipitation on the official National Weather Service instruments at BWI-Marshall Airport. Writers insist that their own observations - some anecdotal, some recorded on home rain gauges - are often/usually higher than those at the airport.

We have posted some of these notes from readers. And, we have passed along at least one theory, suggesting that - particularly when wet weather systems move in from the Atlantic as they did during the heavy rains here at the end of June - the rising terrain from the coastal plain (where BWI sits) to the Piedmont forces the wet air to rise. That cools the air temperature and causes some of the moisture to condense, increasing total rainfall on the higher inland terrain.

Here's another theory, from Jack Wennerstrom, of Randallstown. He draws on the same sort of physics, but sees it from another perspective:

"Most parts of western and northern Baltimore County sit higher than Baltimore City. The difference can be dramatic: at Soldier's Delight, a nearby natural area, the Visitor Center is at 726 feet above sea level, as is a nearby hill. For evidence, walk just to the west of the center, at Red Dog Lodge, and gaze westward, and downward, into Carroll County. In the long-ago days when all these hills were clear-cut for timber, from here you could see the Blue Ridge to the west and the Chesapeake Bay to the east.

"Due to uplift and the relative erosion-resistance of the hard surface rock ... this area and others are noticeably higher than the coastal plain ... that they abut. Indeed, they form a series of hills and low ridges that roughly constitute the so-called 'fall-line' on a southwest-northeast axis paralleling Route 1.

"My point is that this line of hills, which come to surround Baltimore west and north, produce a kind of 'mini-rain shadow' effect, whereby west-to-east approaching rain clouds tend to drop their rain on the windward (western) sides of the ridges (as well as the crests), leaving less or little for the lee sides (Baltimore's coastal plain), a phenomenon well-known and more dramatic in lofty western Maryland.

"The result? I believe our annual rainfall here in Randallstown, and surrounding Pikesville, Granite, and Owings Mills is, on average, four to ten inches more than at BWI, which sits on the coastal plain lee, or 'mini-rain'shadow.'  I base my estimate on 20 years of observation, taking notice of official rainfalls here and in these nearby communities. There is a mitigating factor in that rainstorms from the northeast or south, which are much rarer, are not affected by this rain-shadow factor - otherwise the difference would be even higher. Many is the time that I have noted rainfalls of 2, 3 or more inches here in the Randallstown, owings Mills, Pikesville region, while little or none fell at BWI. It is very rarely the other way around.

"So ... the BWI rainfall stats are misleading to a large percentage of the Baltimore-area residents. I know of no one else who holds this theory or has even mentioned the possibility of its existence."

Readers?  What do you think?

Posted by Frank Roylance at 11:28 AM | | Comments (5)
Categories: Ask Mr. Weatherblogger

2006 heat worse than 2002

It's official - at least in my mind. The stretch of 90-degree-plus weather we've seen since in Baltimore since July 27 has been worse than the similar heat wave in 2002. Here's why I think so:

The hot spell in August 2002 lasted 11 days - from Aug. 10 to 20. The daily highs at BWI ranged from 90 degrees to 99 degrees. The average daily high reading during that period was an even 95 degrees.

The 2006 heat wave began July 27 and has continued (so far) through Aug. 6 - also 11 days. But the daily highs at BWI this time have ranged from 90 degrees to 100 degrees. And the average daily high came to 95.45 degrees.

So, the upper end of the range was a degree higher, and the average high was higher. In my book, that makes this stretch of summer heat in Baltimore worse than than in 2002.

And we may not be done with it yet. Today's forecast high at BWI is 92 degrees. If we make it, that will bring the current string to 12 days.  After that, happily, we should see daytime highs closer to the long-term average - in the mid-to upper 80s.

One thing seems clear: the 21-day ordeal of hot - (90-degree-plus, ranging from 90 to 103) - weather in July/August 1988 still takes the cake for duration, at least in recent memory. But it's notable that the average daily high during that period was 93.76 degrees, cooler than either heat wave in 2006 or 2002.

Posted by Frank Roylance at 11:02 AM | | Comments (0)
Categories: By the numbers

August 4, 2006

Heat, haze, humidity - from space

Here's a terrific photo of the Mid-Atlantic coastal states, snapped from orbit Wednesday morning by NASA's Terra Earth observing satellite. It was the start of another day of 100-degree heat and suffocating humidity. Clear skies, but lots of haze and air pollution blowing off the urban centers and out over the Atlantic. Here's the caption material.

Posted by Frank Roylance at 11:18 AM | | Comments (1)
Categories: Cool pictures

Chris fades, tropics quiet

Tropical Storm Chris was downgraded this morning to a tropical depression, with top sustained winds of just 35 mph. It might look like we can write this one off, as a mere rainmaker. But I notice the National Hurricane Center is continuing to follow the storm and issue regular advisories. It also does not appear to be ruling out re-intensification. Elsewhere, the rest of the Atlantic Basin seems pretty darn tranquil.

Here is the latest advisory on the late Chris. Here's the track for what's left of the little guy. And here's what he looks like from space. It's the faint pinwheel at the upper left-hand corner of the screen, moving right to left. And here's a shot of Chris taken by astronauts aboard the International Space Station.  In fact, NASA has a pretty nice briefing on Chris on the Web today.

Posted by Frank Roylance at 11:08 AM | | Comments (0)
Categories: Hurricanes

August 3, 2006

Mercury hits 102 downtown

The thermometer at the Maryland Science Center reached 102 degrees at 2:18 p.m. today. It was the third day in a row of 100-plus temperatures there. (It was 101 on Tuesday and Wednesday.) The heat index was a stifling 112 degrees.

Out at BWI, it was 100 degrees at 3:48 p.m. That tied the record for the date, set in 1931. It was the second 100-degree day at BWI in the last three. (It was "only" 99 there on Wednesday.)

The National Weather Service said the last time temperatures reached 100 degrees on three consecutive days in Baltimore was on July 2,3 and 4, 1966. That was at BWI, however, so this week's triple play at the Inner Harbor isn't a match.

Friday's record is 100 degrees, so we're not expecting any threat to that mark from the waning heat wave. Highs are expected to hold in the low 90s as cooler air moves in from the Great Lakes. Eighties resume for the weekend, the first days that cool since July 26.

Living in Baltimore this week has been like walking around and breathing inside somebody else's bed. Happy to see the end of it. You?

Posted by Frank Roylance at 8:09 PM | | Comments (3)
Categories: Events

How to cool a "heat island"

Most of the time, we ignore the temperatures recorded in downtown Baltimore. The National Weather Services decided back in 1950 that the thermometer readings they were getting from the instruments on the roof of the Customs House were unreliable, and not representative of the surrounding region. Rooftops are notoriously hot, and the brick and stone buildings, concrete sidewalks, asphalt roofs and streets, smokestacks and air conditioning exhaust all make cities hotter than their surrounding suburbs and countryside, especially at night.

So, in 1950, the weather service moved Baltimore's station of record out of the city, and established Friendship Airport - now BWI Marshall - as the spot where official "Baltimore" weather data has ever since been gathered.

In April 1998, the weather service decided that the roof of the Customs House was not even a good place to record urban temperatures. So, they built a new station beside the Maryland Science Center, and discontinued data collecting at the Customs House after nearly a century of continuous record-keeping.

Unfortunately, it wasn't an ideal choice. The spot is often sheltered from the wind by the Science Center itself. And, because the site isn't a priority station for the weather service, breakdowns aren't fixed quickly, and large data gaps crop up. The station does not report wind, visibility, and sky condition. Only temperature, dew point, precipitation and barometric pressure are reported. Temperatures there are usually warmer than at BWI, reflecting a continuing heat island effect. We've seen it again this week, with Inner Harbor highs breaking 100 degrees on Tuesday and Wednesday, while BWI highs lagged by a degree or two. But I digress.

Climate scientists have done quite a bit of research on the impact of urban development on the micro-climate of a big city. For example, they've established that cities affect the weather. The extra heat rising from a city creates updrafts and convection that lift warm, moist air high into the atmosphere. There, it cools, the moisture condenses out as rain, and regions downwind of the city actually get increased rainfall.

This heat island effect also increases the misery and cooling costs of city residents, and that has prompted research into how the effect might be dampened by planting roof gardens, resurfacing rooftops in white instead of black, and simply planting more trees in our cities.

All of this brings me to a point where I can provide a link to an interesting discussion of some recent NASA-funded research into the issue. Here's the link. Be sure to follow the blue links at the bottom of each page. There's lots to read here.

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

Chris is sheared off

Tropical Storm Chris got his top knocked off overnight. Shearing winds from the northwest blew the top off the storm, separating the storm center from the convection and thunderstorm activity that powered it. You can watch it in the satellite loop. Notice how the bright storm activity veers off toward Puerto Rico, while the pinwheel structure of the storm's center keeps churning toward the west, like a horse that's lost its rider.

The bottom line is that the storm is weakening as it tracks mostly westward, just north of Puerto Rico and Hispaniola. It may not even be able to maintain tropical storm strength (39 mph). All hurricane warnings in the Bahamas have been downgraded to tropical storm warnings.

Here's the latest advisory. And here's the forecast track, which carries the storm center across to the Gulf.

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

August 2, 2006

Rain on Titan is mainly methane

Scientists scouring photos sent back by the Cassini spacecraft now circling Saturn have spotted what they believe are lakes of liquid methane on Titan, the largest moon of Saturn. They also believe the methane may run into those lakes after falling as rain. Naturally, a space artist has ginned up a picture to illustrate what that might look like to an astronaut on the surface. It's pretty cool.

Posted by Frank Roylance at 6:59 PM | | Comments (0)
Categories: Cool pictures

Chris could become a hurricane today

Tropical Storm Chris continues to churn its way past the northern Leeward Islands, threatening heavy rains (2-4 inches) across the Virgin Islands and Puerto Rico in the coming days as the storm's center passes to their north. Top sustained winds at last check were exceeding 65 mph. Some strengthening is expected, so Chris could become a Category 1 hurricane later today.

Hurricane watches are already up for the Turks & Caicos Islands, and the southeastern Bahamas.

The rising question is whether the storm will pose a significant risk to South Florida. That will depend on how it's affected by the surrounding wind and water environment and the mountains of Puerto Rico.

Here is the latest advisory. Here is the current forecast track, which would carry it into the warm waters of the Gulf of Mexico, as a hurricane, by Monday morning. Here is a data bouy in the Gulf, where the water temperature was 86 degrees this morning. And here is a satellite view.

Posted by Frank Roylance at 11:37 AM | | Comments (0)
Categories: Hurricanes

A record at BWI

My bad. The instruments at BWI clocked a new record high temperature yesterday, and I missed it. The heat topped out at 100 degrees, breaking the previous record of 99 degrees for an Aug. 1, set back in 1933. I had been monitoring the hourly readings from BWI-Marshall, which plateaued at 98. What I failed to notice was that it had hopped to 100 degrees and back between the top-of-the-hour observations.  We have corrected our on-line story, and will make reference to the new record in tomorrow morning's dead-tree editions.

The record high for today - Aug. 2 - is also in peril. The high mark is 100 degrees, set in 1955.

The high at the Maryland Science Center yesterday, meanwhile, also twitched higher than the 100 degrees we reported in today's story. It actually made it to 101 degrees. The Weather Page, at least, got it right.

Rumors are flying, as well, that July 2006 may have been the hottest on record for the continental United States, busting the record set in 1936. The National Oceanic and Atmospheric Administration is crunching the numbers and is expected to announce the results in two days.

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

August 1, 2006

Inner Harbor hits 100

The 4 p.m. reading at the Maryland Science Center, along Baltimore's Inner Harbor promenade, reached 100 degrees Fahrenheit just before 4 p.m. today.  It's the first time the mercury has hit 100 at the harbor since July 23, 2002. However, it was 99 degrees twice last month - on July 17 and yesterday - the 31st.

The official high for Baltimore, meanwhile, was 98 degrees, at BWI Airport. That was NOT a record. The official record for Baltimore for Aug. 1 is 99 degrees, set at the Customs House downtown in 1933. The station of record for Baltimore was moved in 1950 from the Customs House to what was then Friendship Airport. 

Unfortunately, it's no longer possible to establish downtown records. For starters, the downtown instruments were moved on April 29, 1998 from the roof of the Customs House, which was judged to be inaccurate due to rooftop heating, to the Lawn of the Maryland Science Center. So we would be comparing apples and oranges (although we do that anyway by using pre-1950 data from downtown AND post-1950 data from the airport as if it were a continuous record.)

But beyond that, the Science Center instruments do not provide a reliable, comprehensive weather record, and they are not maintained as well by the weather service. As a consequence, there are gaps in the data, sometimes extending for many days. 

Posted by Frank Roylance at 4:22 PM | | Comments (0)
Categories: Events

Record heat ahead

There's a good shot we'll set some heat records this week. Here is the summary of the possibilities, laid out by the National Weather Service folks at Sterling.  It contains at least one error. The last 100-degree day in Baltimore was July 4, 2002, not August. But we forgive them.

Posted by Frank Roylance at 11:09 AM | | Comments (0)
Categories: Forecasts

A stirring in the tropics

The tropical Atlantic, which has been notably quiet so far this season, has finally spawned the third named tropical storm of the season. TS Chris is drawing a bead on the northern leeward islands - in the northeastern Caribbean. It does not appear terribly dangerous for the moment. But we've learned a lot in recent years about these storms, and every one of them bears watching.

Here is the latest advisory on Chris from the National Hurricane Center. Here is the forecast storm track, which could put it near South Florida by Sunday. And here is the view from orbit.

Posted by Frank Roylance at 10:33 AM | | Comments (1)
Categories: Hurricanes
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About Frank Roylance
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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Maryland Weather Center

Area Weather Stations
Resources and Sun coverage
• Weather news

• Readers' photos

• Data from the The Sun's weather station

• 2011 stargazers' calendar

• Become a backyard astronomer in five simple steps

• Baltimore Weather Archive
Daily airport weather data for Baltimore from 1948 to today

• National Weather Service:
Sterling Forecast Office

• Capital Weather Gang:
Washington Post weather blog

• CoCoRaHS:
Community Collaborative Rain, Hail and Snow Network. Local observations by volunteers

• Weather Bug:
Webcams across the state

• National Data Buoy Center:
Weather and ocean data from bay and ocean buoys

• U.S. Drought Monitor:
Weekly maps of drought conditions in the U.S.

• USGS Earthquake Hazards Program:
Real-time data on earthquakes

• Water data:
From the USGS, Maryland

• National Hurricane Center

• Air Now:
Government site for air quality information

• NWS Climate Prediction Center:
Long-term and seasonal forecasts

• U.S. Climate at a Glance:
NOAA interactive site for past climate data, national, state and city

• Clear Sky Clock:
Clear sky alerts for stargazers


• Hubblesite:
Home page for Hubble Space Telescope

• Heavens Above:
Everything for the backyard stargazer, tailored to your location

• NASA Eclipse Home Page:
Centuries of eclipse predictions

• Cruise Critic: Hurricane Zone:
Check to see how hurricanes may affect your cruise schedule

• Warming World:
NASA explains the science of climate change with articles, videos, “data visualizations,” and space-based imagery.

• What on Earth:
NASA blog on current research at the space agency.
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