Weather blog from MarylandWeather.com

Saturday is your best bet for the weekend

Fri, 20 Nov 2009 14:01:53 -0500

If you're hoping for at least one good outdoor day this weekend, it looks like Saturday will be your best bet. The next coastal storm in this autumn's continuing parade is fixing to spin on up the East Coast, and we're likely to fall under its rain shield as early as Sunday afternoon.

Saturday, however, looks great for a hike or a roll up the bike trail. High pressure centered in the Ohio Valley is building across the region today (Friday) and will bring us more sunshine Saturday, with a high in the upper 50s.

The relatively mild temperatures are the work of bright sunshine, and something called "downsloping." Winds out of the west or northwest flow across the Appalachians and slide down the eastern slope. And as they descend, the air is compressed, which warms it up. The average highs at BWI at this time of year are in the mid-50s.

By Sunday, however, clouds will be on the increase, with the chance of showers rising in the afternoon as a low-pressure system forming over the Gulf moves off the Southeast coast. The computer models disagree, of course, on the timing, and on how close the low will come to the shore. And, as it does with winter storms, that storm track will determine just how much precipitation we see.

Whatever we get, it's likely to arrive late Sunday into Monday. We may get a brief look at the sun again on Tuesday, but there's more rain likely at mid-week as the next cold front slides by. From this distance, Thanksgiving Day is looking like a gray one, too, with a 40 percent chance of rain.

(SUN PHOTO/Jerry Jackson/2007)

An account of deadly 1926 La Plata tornado

Thu, 19 Nov 2009 17:06:42 -0500

Steve Zubrick, science and operations officer at the National Weather Service in Sterling, Va., has sent me a link to an historic National Weather Service report on the Nov. 9, 1926 tornado that swept across parts of Charles and Prince George's counties, leaving 16 dead (or 17, depending on your source) - including 13 school children.

The F-4 twister demolished homes and barns, carved a cross-country trail of splintered trees and carried debris as far as 50 miles before dropping it. A school teacher describes how she and her students were lifted into the air and swept away, along with parts of their demolished schoolhouse.

Sun reporter Fred Rasmussen interviewed one of the school's students, who survived because she was not in class that day; but her sister was among the dead. (No, Fred's not quite that old; the woman was in her 80s when they spoke.) Read his story, below.

Fred tracked the woman down after a similar tornado struck La Plata in April 2002. Only the third F-4 in the record books for Maryland, the 2002 tornado ravaged the town and cut a path all the way across Southern Maryland. It then spawned a waterspout on the bay, and touched down again on the Eastern Shore. Six people died. The photo above was taken four days later.

More rain due; east wind brings high water

Wed, 18 Nov 2009 18:16:07 -0500

Thursday looks like a wet one as clockwise winds around a high pressure system to our northeast continues to pump an east wind and Atlantic moisture our way.

Forecasters are calling for drizzle, showers or rain late tonight, followed by a 70- to 80-percent chance for more rain on Thursday as a cold front approaches from the west. In the meantime, the east wind is shoving bay water on the western shore, with flood advisories posted for the bay south of Baltimore and for the tidal Potomac River. Feels just like last week's forecast.

Behind the cold front we'll get some clearing for nice weather Friday and Saturday. But then the next coastal storm will be firing up off the Carolinas, with another bout of rain due late Sunday into Monday.

No wintry precip expected around the northwest side of that storm, except perhaps at the very highest elevations to our west. But this pattern of repeated coastal storms bodes well for snow lovers if it keeps up through the colder months.

Western "fireball" may have been small asteroid

Wed, 18 Nov 2009 17:22:05 -0500

A brilliant meteor that startled residents across parts of Idaho and northern Utah early Wednesday morning may have been a small asteroid, scientists say. It exploded in the atmosphere with a force equal to a thousand tons of TNT.

Spaceweather.com reports:

"Witnesses in Colorado, Utah, Idaho and elsewhere say the fireball "turned night into day" and "shook the ground" when it exploded just after midnight Mountain Standard Time. Researchers who are analyzing infrasound recordings of the blast say the fireball was not a Leonid. It was probably a small asteroid, now scattered in fragments across the countryside. Efforts are underway to measure the trajectory of the asteroid and guide meteorite recovery efforts."

Security camera footage of the event shows a flash that brightened the sky so much that a street light operated by a light sensor winked out for a time before the sky grew dark again.

Here's a video from local TV.

If this was a small asteroid (or a big space rock of some sort) entering the atmosphere, it would be second one in recent weeks to make news.

"Vomitoxin" disaster declared in 10 Md. counties

Tue, 17 Nov 2009 15:18:08 -0500

A fungal grain infestation caused by last spring's wet weather in Maryland was bad enough to earn a federal agricultural disaster declaration for 10 Maryland counties. U.S. Agriculture Secretary Thomas J. Vilsack approved the state's request for aid in a Nov. 13 letter to Gov. Martin O'Malley.

Wheat and barley crops planted here became infected with the Vomitoxin (deoxynivalenol toxin, or DON) during May and June. The toxin is produced by a fungus called "Fusarium head blight," and the contamination makes the grain unmarketable, and unusable as feed.

The North Dakota State University describes its impact this way: "Grain with DON would have to be ingested in very high amounts to pose a health risk to humans, but it can affect flavors in foods and processing performance. Human food products are restricted to a 1-ppm level established by the FDA. This level is considered safe for human consumption. The food industry often sets standards that are more restrictive. DON causes feed refusal and poor weight gain in some livestock if fed above the advisory levels."

Maryland Agriculture Secretary Buddy Hance said, "Farmers in the disaster designation areas experienced market value losses ranging from 30 to 55 percent."

The federal disaster declaration makes farmers in the primary designation areas, and all adjoining counties, eligible for "consideration" for assistance from the USDA Farm Service Agency.

The primary counties in the disaster declaration are Baltimore, Carroll, Cecil, Harford, Howard, Kent, Montgomery, Queen Anne's, Talbot and Washington.

BWI Marshall Airport recorded more than 9 inches of surplus rain during April, May and June. Since then, more than 3.5 additional inches of surplus rain have been added.

(SUN PHOTO/Glenn Fawcett 2008)

Tom Turkey on the road to ... dinner

Tue, 17 Nov 2009 14:50:46 -0500

I was driving to work on I-83 Monday when I pulled alongside this flatbed truck from Locust Point Farm in Elkton, loaded with cages holding dozens of turkeys. It wasn't hard to imagine where they were headed. Fortunately for these guys, we celebrated early. All turkeyed out.

Speaking of seasonal critters, anyone else under siege by box elder bugs and ladybugs? They all want to come indoors. Crickets, too.

Last week's rain totals mapped

Tue, 17 Nov 2009 14:39:19 -0500

The National Weather Service has produced a map of the 72-hour rain totals during last week's nor'easter.

The map makes clear just how much more seriously affected counties to our south were, and especially those in southeast Virginia (left). Rain totals there ran above 10 inches in some places.

Out in far-western Maryland, meanwhile, there was little or no rain from the coastal storm.

(AP Photo/Jason Hirschfeld in Hampton Roads. Va. Nov. 13, 2009)

Antarctic ozone hole shrinks, a little

Tue, 17 Nov 2009 11:02:56 -0500

The ozone "hole" over Antartica reached its southern springtime peak in September, according to researchers with the National Oceanic and Atmospheric Administration. Measurements there indicated the size of the gap in the layer of the planet's atmosphere that protects us from dangerous ultraviolet radiation was the 10th largest on record.

That sounds bad, but the data suggest that the hole has actually begun to shrink thanks to international restrictions in the early 1990s on the production and sale of products containing chlorofluorocarbons (CFCs), mostly as propellants and refrigerants. The chemicals were discovered to be responsible for high-altitude chemical reactions in the coldest places on Earth that were destroying ozone molecules. Man-made ozone is a pollutant at ground level, but naturally occurring ozone high in the atmosphere acts as a shield against harmful solar radiation.

The other piece of the measurement is the amount of ozone in a vertical column of air over South Pole Station. That's measured in something called Dobson Units.

The least amount of protective ozone ever measured there was 89 Dobson Units, in 1993. This September, the lowest reading was 98 Dobson Units. That's the seventh lowest on record, but an improvement.

The chart at right shows the average Dobson readings for the last half of October each year. You can see that the depletion appears to have ended during the 1990s, and ozone readings have stabilized and perhaps ticked up a notch.

But the progress is painfully slow. At this rate, the ozone hole won't return to normal until the 2060s. By then, lots of us (including me) will be dead. But our children and grandchildren will be around, and I hope they throw a big party and thank their ancestors for thinking for the long-term (for a change).

You can read more about this year's measurements here.

Forecast hopeful for Leonid meteor shower tonight

Mon, 16 Nov 2009 14:52:46 -0500

With the moon entering its "new" phase tonight, the skies should be ideally dark for viewing Tuesday morning's peak of the annual Leonid meteor shower. And the weather forecast, while not ideal, calls for partly to mostly clear skies. With cooler air moving in with a high-pressure system out of the Great Lakes, our skies should be drying out from this morning's foggy humidity. That will help clear the atmosphere for the best view of the "shooting stars."

The Leonids occur each November when the Earth, in its annual orbit around the sun, passes through remnants of the dust trails left behind by the passage of Comet Tempel-Tuttle, which passes through this area of the solar system every 33 years. Astronomers say the trails we'll be intersecting tonight were laid down by the comet in AD 1466 and 1533.

Here's more from Sky & Telescope.

UPDATE: Here (left) is a meteor captured by amateur astrophotographer Mike Hankey, in northern Baltimore County, during the Leonid shower. It may be a "sporadic," rather than a Leonid. Still a nice shot, better than anything I've ever managed. Mike said:

"At the time I was focused on Procyon and shooting continuously and waiting and watching. I saw a meteor radiate directly out of [the bright star] Procyon and was like, NO WAY! But I check the camera screen and couldn't see anything. I didn't realize I caught it until this morning when I was reviewing the pics.

"It was much brighter in person, it's a little faint in the pic. Still really happy I caught it."

Here's Mike's Web site.

Earlier post resumes here:

Some Leonid showers have reached "storm" proportions, with counts of more than 1,000 per hour in some locations. This year's show, for eastern North America, is expected to produce rates of a more conventional 20-30 per hour. But any time you can spend an hour under the night sky and see 20 meteors, some with persistent trails, is a memorable night out.

The best time to look will be in the hours before dawn - say, 3 or 4 a.m. until the dawn begins to brighten the sky.

Intrepid meteor watchers should find the darkest location they can, as far from urban light pollution as possible. Look for a place with a broad view of the sky. The shower's "radiant" is the constellation Leo - the place in the sky from which the meteors seem to emerge as the Earth plows into them.

Leo rises in the northeast after 11 p.m. By 4 a.m. it will be high overhead, and the meteors will appear to be flying away from it in all directions. So you can look anywhere for them.

When it's over, as always, come back here, leave a comment and let everyone share the experience. Good luck!

24-hour rain totals top 5 inches in St. Mary's Co.

Fri, 13 Nov 2009 10:35:41 -0500

While Baltimoreans may simply be tired of the gray, and the gloom, and the drip, residents of Maryland's southern counties - on both sides of the Chesapeake, are dealing with a serious deluge of rain and high tides from the big coastal storm that remains almost stationary off the Carolina coast, driving wind, rain and water inland.

Here's an animation of the storm's water vapor movement, from satellite sensors.

Precipitation totals in St. Mary's County for the past 24 hours have topped 5 inches, with some locations reporting nealy six inches and one - Great Mills - exceeding 7 inches. Normal rainfall for the month of November at BWI is 3.12 inches.

Here is a rain total map for the storm.

High water and fallen trees have forced a number of road closings in the Leonardtown area, and delayed delayed school for some students Thursday as buses were re-routed around flooded roadways.

Ocean City has received 3.69 inches of rain since the storm arrived, the heaviest falling early Thursday evening. That's the Rehoboth Beach Web cam below.

Coastal Flood Warnings remain in effect Friday morning for Charles, Calvert and St. Mary's counties. Tides were expected to run 2.5 to 3 feet above normal into Saturday before the storm begins to drift away from the mainland. Colton's Point and St. George's Island in St. Mary's County, and Solomons Island in Calvert were warned to expect significant flooding.

In addition, Ocean City was under Wind Advisories until 7 p.m. Friday. An earlier hHigh Wind Warning was cancelled. Winds are now forecast to average 25 to 35 mph, with gusts to 50 mph before weakening late in the day. With the soil saturated, such winds can be expected to topple some trees, causing more power outages. The Atlantic coast is also under a High Surf Advisory until 6 p.m. Friday. Tides at the Inlet are expected to exceed predictions by more than 5 feet, with moderate flooding in Ocean City.

Coastal Flood Advisories were up for Anne Arundel and Prince George's counties. Gale warnings and small craft advisories were posted for the Chesapeake.

The rain amounts decrease as you travel north almong the Western Shore. Prince Frederick, In Calvert County, recorded 4.18 inches by Friday morning. Baltimore-Washington International Thurgood Marshall Airport reported 1.24 inches. The storm has left just under an inch here at The Baltimore Sun in downtown Baltimore.

Here is a list of rain reports, as of Friday morning, from the National Weather Service.

As thick and damp and gloomy as it is here, it's interesting to note that clear, dry, sunny weather lies barely 150 miles to our west, beyond the reach of this slow-moving nor'easter.

Oakland, in Garrett County, is reporting "a few clouds" this morning. Elkins, W.Va. is sunny. So are Pittsburgh, Pa., and State College, Pa.

Storm sits and spins; we get wet

Thu, 12 Nov 2009 10:18:09 -0500

That storm off the Carolinas continues to churn on Thursday, stoked by energy and Gulf moisture from the remnants of Tropical Storm Ida. Coupled with the high over New England, the two weather engines are sending northeast and east winds onshore, bringing us a steady drip of rain, and driving tides high onto the east-facing shores of the Atlantic and up the Chesapeake.

Here's the view from orbit. Here's Weather Underground blogger Jeff Masters, calling the storm surge at Norfolk "historic." And here is more on the storm from NASA.

The National Weather Service has issued a slew of watches and warnings today as tides swell toward minor-to-moderate flood levels. High winds and heavy rain mostly south and east of Baltimore and Washington are adding to the local problems, which have already resulted in some road closures in Southern Maryland. More are expected.

Leonardtown and Hollywood, both in St. Mary's County, have already reported more than 2 inches of rain from the storm. Ocean City, too, was getting hammered by rain, wind and high water.

The forecast for BWI coming out of Sterling calls for a pretty steady rain Thursday and Friday, with rain chances only slightly reduced for Friday, but diminishing overnight and into Saturday morning. The drying out should begin later on Saturday, with sunshine on tap for Sunday and the early part of next week. In all, Baltimore could see as much as an inch of additional rain, on top of the inch or so we've already recorded. If this were January we'd be out shoveling.

Among the many watches and warnings out this morning:

The NWS has issued coastal flood advisories for the Western Shore of the Chesapeake, where tides were running a foot above predicted levels Thursday morning at Annapolis (right), with higher levels expected at high tides times on Friday.

Flood watches and warnings are up for Friday from Anne Arundel County south to St. Mary's. Md. 244 near Redgate and Old Rolling Road in Great Mills were flooded in spots this morning as heavy rains drove streams over their banks, county authorities there reported.

Gale Warnings (winds 34 to 47 knots) are up for the northern portion of the Chesapeake, including Baltimore Harbor, with Storm Warnings (winds 48 to 63 knots) until 6 Thursday evening for the southern portion.

A High Surf Advisory is up for the ocean beaches, with rip currents and local beach erosion expected. Here are some OC Web cam views of the surf.

Developing coastal low deals us rain into weekend

Wed, 11 Nov 2009 10:20:00 -0500

Persistent northeast winds, energized by a slow-moving coastal storm intensifying off the Carolinas, and high pressure over New England, will keep Maryland in a northeasterly flow off the Altantic for the rest of the week. And that will mean a series of cool, gray, drippy days, with gusty winds and increasingly high tides. So much for what had been a sunny forecast for the end of the week.

Some of this mess can be linked to the remnants of Tropical Storm Ida, including much of the rain that has moved into the region overnight and the energy that is fueling the coastal storm.

The counter-clockwise flow around the coastal low is combining with the clockwise flow around the New England high-pressure center. And that is funneling northeast winds into the region.

The storm is shoving Gulf and Atlantic moisture northward into the region, where it is running up against the cold front and clear, dry air, that lies to our north and west. And that flow is what's delivering our drizzle and rain today. (Those are The Sun's ginkgo trees, on Calvert Street, at right. The photo doesn't do them justice.)

The heaviest rain is expected to remain south and east of the Baltimore-Washington area. So will the gale-force winds forecast for the central and southern portions of the Chesapeake. Along the coast, winds will reach 15 to 20 mph in the next day or two, with gusts to 25 or 30 mph.

All that wind, coupled with an approaching new moon, will drive more water onto the beaches, and hold it against the Chesapeake shoreline. Coastal Flood Watches have been posted for Friday on the Chesapeake Bay and the tidal Potomac River. Minor to moderate flooding is possible at periods of high tide Friday afternoon and Saturday.

A Gale Warning is up for Thursday on the lower tidal Potomac and the Bay south of Sandy Point.

Out on the ocean beaches, there is heavy rain in the forecast. (Ocean City's beaches, left, were deserted this morning.)

The National Weather Service's Wakefield, Va. forecast office has posted High Wind Warnings from Maryland to the Outer Banks, effective from 6 p.m. Wednesday evening until 11 a.m. Friday morning. Winds will average 30 to 40 mph with higher gusts.

High Surf Advisories Coastal Flood Warnings are also up for the Delmarva beaches, with tides two to four feet above predicted levels.

October was wettest, third-coolest on record for U.S.

Tue, 10 Nov 2009 16:02:28 -0500

NOAA's October data are in, and the agency is rpeorting the October in the U.S. was, on average, the wettest, and the third-coolest October on the 115-year record for the lower-48 states.

Temperatures were below-normal in all regions except the Southeast (and in New Jersey, Delaware and Maryland, which were near-normal). Florida was the only state to report above-average temperatures. (Left)

The cross-country average of 4.15 inches of rain was the highest on record, nearly doubling the long-term average for October. Moderate-to-exceptional drought covered 12 percent of the contiguous United States, the second-smallest drought footprint of the decade, based on the U.S. Drought Monitor.

You can read the entire release, here. (Cue the global warming skeptics...)

On the other hands, atmospheric scientists say the proportion of record high temperatures to record lows across the U.S., is going up.

Ida's remnant rain may stay mostly south of us

Tue, 10 Nov 2009 11:32:28 -0500

Forecasters at the National Weather Service's Sterling forecast office are wrestling with computer models that can't quite agree on how much of Ida's moisture will make it to Maryland this week.

Remnants of what was once the third hurricane of the 2009 season have crossed the Gulf Coast and swept inland, bringing heavy rains to parts of the Deep South. But there is high pressure to our northwest, and a cold front ahead of it that appears to constitute a barrier to the northward advance of Ida's rains.

"It's the remnants of Ida, and how quickly/how far its rainfall spreads northward that will determine the outcome of this forecast," the forecasters say in this morning's discussion.

For now, the official forecast out of Sterling is calling for a chance for rain to develop after 10 p.m. this evening as the Gulf moisture begins to run up against the cold front. Veterans Day comes with a 30 percent chance for rain or drizzle, with temperatures held in the mid-50s. The drizzle chances continue in to the evening. But the rest of the week, and right into early next week, looks sunny with seasonable highs near 60 degrees.

Whatever happens here, it appears the coastal counties will see some considerable wind and rain in the next few days, with some chance for minor coastal flooding as a series of offshore lows keep persistent northeast winds shove more water onto the bay and ocean shorelines.

Reader recalls early 1953 snowstorm

Tue, 10 Nov 2009 10:43:18 -0500

Last week I wrote a brief comment on the print weather page about the early snowstorm that paralyzed Baltimore back on Nov. 6-7, 1953. I wondered if anyone would remember the storm, which was the earliest "heavy" (four inches or more) snowfall in Baltimore weather records.

This week I received the following note from Joan Parr, who clearly did. She writes:

"Mr. Roylance:

"If my memory serves me right, the storm you mentioned in your blog (on Friday, Nov. 6. 2009) was indeed a traffic-snarler. Drivers acted as if they had never seen snow before, and they just kept moving, right into intersections, creating gridlock.

"This storm was, I believe, the impetus for Baltimore City to lure Henry Barnes away from Denver to come and make sense of our streets and traffic lights. He did a very good job; one of his legacies which still exist in Baltimore is the "Barnes Dance," where all vehicular traffic is stopped and pedestrians are free to walk across the streets unobstructed by cars and trucks.

"Thank you for the reminder of that storm. Joan K. Parr "

(SUN PHOTO/Nov. 6, 1953/Cecil County)