Archive for February, 2009

Saturday Storm Update
February 28, 2009

Evidence continues to build that a nor’easter is developing and could hit the area with a significant snowfall by the start of the work week.

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A large scale storm is developing in the southeastern U.S. and is the breeding ground for what are expected to be two storms that will move up the Atlantic coast this weekend.

The first will be the smaller scale of the two and will produce a wintry mix of precipitation Saturday night and early Sunday. Relatively light accumulations of snow or a snow/sleet combination are likely.

The second storm may pack a bigger punch.

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The timeline and estimated track of the storm is shown above.

Below is a detail of what the weather map may look like Sunday evening.

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As of midday Saturday the expected track of the storm will put the low pressure center just close enough to the Mid Atlantic coast to allow for the threat of a significant snowfall in the area. This forecast track still needs fine tuning. If it should move any farther east the threat of a heavy snow snow would be reduced.

The final phase of the storm is expected to pull away from the area on Monday. What will it leave behind?

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The computer estimate above shows that the area surrounding the upper reaches of the Bay could see 6 to 9 inches of snow. A couple of spots on the northern DELMARVA Peninsula might even approach a foot of snow. Keep in mind that this is an EARLY ESTIMATE. A lot could happen to change the course of the storm in the next 24 to 48 hours and significantly alter these numbers. Needless to say, stay tuned. We’ll keep you updated.

By the way, a couple of days ago I wrote in a blog something to the effect  that it wouldn’t hurt to get a couple of storms so we could catch up on some much needed precipitation. It just goes to show you that you need to watch what you ask for!

John Collins

March 2009 may roar into Maryland
February 28, 2009

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After Friday’s 65° warmth it is hard to believe cold and wintry weather will be trying to move into Maryland this weekend. However, a glance at the temperature map late Friday evening provides a quick reality check! As of 11pm Friday, International Falls, MN was down to -23°, Marquette, MI had dropped to -12°, Pittsburgh was 27° and Baltimore was holding onto 53°…a 76° contrast from the mid Atlantic to the upper midwest! Northerly winds on Saturday will tap into that arctic air mass while low pressure forms on the front as it stalls off the south Atlantic coast. As the low moves north into the colder air, a mix of rain, sleet and snow will be possible throughout the region Saturday night into Sunday morning. A second low is expected to move up the coast Sunday night into Monday morning. This series of coastal lows may produce significant snow and sleet accumulations. It is too early to nail down snowfall forecasts, but the early projections for snow totals from Saturday night through Monday morning show a few inches in central Maryland, with heavier amounts possible on the eastern shore and closer to the coast. These early projections could easily change as the track of the lows becomes clearer. Stay tuned to WBAL-TV and check back here on wbaltv.com for updates over the weekend.

Tom Tasselmyer

Baltimore’s Driest Februarys
February 27, 2009

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With just .24″ of total precipitation so far this month, February 2009 is on the verge of becoming the driest February on record for Baltimore, breaking the old record set just 7 years ago.  Whether these numbers hold up on the last two days of the month will depend on the showers that develop as a cold front moves through Friday evening and a possible coastal storm coming up from the south Saturday night and Sunday.

Tom Tasselmyer

On The Dry Side
February 26, 2009

Temperatures are rising in advance of a weather system that hopefully will bring some needed precipitation to the area.

latest6Thursday (2/26/09) Late Morning Satellite Image

Most of the weather chatter recently has been about the lack of snow this season. Only 3.3 inches has been measured at BWI-Marshall, 11.8 inches below the seasonal average. Not only is this bad news for snow lovers but it also reflects a general shortfall in liquid precipitation across the region in recent months.

So far this year, total liquid precipitation (rain and snow combined) at BWI-Marshall has measured 2.97 inches, 3.16 inches below the seasonal average.

In 2008 the annual precipitation was 3.03 inches above average but the last six months of the year fell 2.92 inches below average. The real impact going into spring is reflected in the numbers from July 1, 2008 through yesterday … a 6.08 inch shortfall of precipitation.

If you have driven past any of the area reservoirs recently you may have noticed that they are down a little and it would be reassuring to see those levels come up before summer. Be it rain or snow, it wouldn’t be a totally bad thing to see several good storms move through the region over the next month or two.

John Collins

Comet Lulin
February 23, 2009

A new comet will be visible in the southeastern sky this week. The icy space object is called Lulin and was discovered last year.

Lulin will be closest to earth over the next couple of days and, with the aid of binoculars, may be visible from the Mid Atrlantic region on a clear night away from city lights. It will be a fuzzy object compared to the sharper points of light that planets and stars make in the night sky.

The graphic below shows Lulin’s position relative to a couple of the brightest objects in the southeastern sky.

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The article that follows is from NASA concerning the comet.

John Collins

NASA’s Swift Spies Comet Lulin
02.20.09

Swift image of comet Lulin taken Jan. 28 This image of Comet Lulin taken Jan. 28 merges data acquired by Swift’s Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). At the time of the observation, the comet was 99.5 million miles from Earth and 115.3 million miles from the sun. Credit: NASA/Swift/Univ. of Leicester/Bodewits et al.
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While waiting for high-energy outbursts and cosmic explosions, NASA’s Swift Gamma-ray Explorer satellite is monitoring Comet Lulin as it closes on Earth. For the first time, astronomers are seeing simultaneous ultraviolet and X-ray images of a comet.

“We won’t be able to send a space probe to Comet Lulin, but Swift is giving us some of the information we would get from just such a mission,” said Jenny Carter, at the University of Leicester, U.K., who is leading the study.

“The comet is releasing a great amount of gas, which makes it an ideal target for X-ray observations,” said Andrew Read, also at Leicester.

A comet is a clump of frozen gases mixed with dust. These “dirty snowballs” cast off gas and dust whenever they venture near the sun. Comet Lulin, which is formally known as C/2007 N3, was discovered last year by astronomers at Taiwan’s Lulin Observatory. The comet is now faintly visible from a dark site. Lulin will pass closest to Earth — 38 million miles, or about 160 times farther than the moon — late on the evening of Feb. 23 for North America.

On Jan. 28, Swift trained its Ultraviolet/Optical Telescope (UVOT) and X-Ray Telescope (XRT) on Comet Lulin. “The comet is quite active,” said team member Dennis Bodewits, a NASA Postdoctoral Fellow at the Goddard Space Flight Center in Greenbelt, Md. “The UVOT data show that Lulin was shedding nearly 800 gallons of water each second.” That’s enough to fill an Olympic-size swimming pool in less than 15 minutes.

Swift can’t see water directly. But ultraviolet light from the sun quickly breaks apart water molecules into hydrogen atoms and hydroxyl (OH) molecules. Swift’s UVOT detects the hydroxyl molecules, and its images of Lulin reveal a hydroxyl cloud spanning nearly 250,000 miles, or slightly greater than the distance between Earth and the moon.

Swift image of comet Lulin passing through the constellation Libra Comet Lulin was passing through the constellation Libra when Swift imaged it. This view merges the Swift data with a Digital Sky Survey image of the star field. Credit: NASA/Swift/Univ. of Leicester/DSS (STScI, AURUA)/Bodewits et al.
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The UVOT includes a prism-like device called a grism, which separates incoming light by wavelength. The grism’s range includes wavelengths in which the hydroxyl molecule is most active. “This gives us a unique view into the types and quantities of gas a comet produces, which gives us clues about the origin of comets and the solar system,” Bodewits explains. Swift is currently the only space observatory covering this wavelength range.

In the Swift images, the comet’s tail extends off to the right. Solar radiation pushes icy grains away from the comet. As the grains gradually evaporate, they create a thin hydroxyl tail.

Farther from the comet, even the hydroxyl molecule succumbs to solar ultraviolet radiation. It breaks into its constituent oxygen and hydrogen atoms. “The solar wind — a fast-moving stream of particles from the sun — interacts with the comet’s broader cloud of atoms. This causes the solar wind to light up with X rays, and that’s what Swift’s XRT sees,” said Stefan Immler, also at Goddard.

This interaction, called charge exchange, results in X-rays from most comets when they pass within about three times Earth’s distance from the sun. Because Lulin is so active, its atomic cloud is especially dense. As a result, the X-ray-emitting region extends far sunward of the comet.

“We are looking forward to future observations of Comet Lulin, when we hope to get better X-ray data to help us determine its makeup,” noted Carter. “They will allow us to build up a more complete 3-D picture of the comet during its flight through the solar system.”

Other members of the team include Michael Mumma and Geronimo Villanueva at Goddard.

NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the Swift satellite. It is being operated in collaboration with partners in the U.S., the United Kingdom, Italy, Germany and Japan. NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics observatory developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.
Francis Reddy
NASA’s Goddard Space Flight Center

Clipper to Nor’easter
February 22, 2009

The “clipper” storm that coated to Midwest and Great Lakes with snow is moving across the Mid Atlantic region with generally light precipitation.

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Probably the most interesting aspect of this storm is that it will eventually develop into a nor’easter once it is out over the Atlantic Ocean. It will then head for coastal New England with a considerable load of moisture. Generous coastal rains and heavy inland snows are likely.

For snow lovers, this storm has been a disapointment in the Mid Atlantic region. While a couple of inches of snow is possible in the mountains, only a dusting is likely in a few spots elsewhere.

At BWI-Marshall, only 4.6 3.3 inches of snow has fallen this season. Typically, by the end of January the area could expect to see nearly 9 inches of snow with an additional 6 inches in February.

John Collins

Weekend Snow Dump Up North
February 20, 2009

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A fast moving area of low pressure will zip through Maryland Saturday night and Sunday morning with the possibility of a light coating of snow in the colder suburbs of Baltimore.  North of here, however, the storm will gain strength off the coast, wrapping moisture from the Atlantic back into the cold air over the New England mountains.  For skiers, the chance for 1-2 feet of fresh snow is a good sign that the season could extend well into March.

Tom Tasselmyer

Storm Moving Away
February 19, 2009

The storm that generated yesterday’s mix of snow, sleet and rain is moving out of the area.

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Gusty, west to northwest winds will bring a reinforcing shot of cold air to the region today.

The departing storm had its’ origins in the Pacific Ocean and started its’ trek across the U.S. last weekend. When it came on shore in California it produced considerable rainfall with snow at higher elevations. The satellite picture below shows the snow the storm deposited in the mountains.

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Of particular interest is the snowfall in the mountains surrounding the Los Angeles Basin and a few of the taller mountains east of San Diego.

John Collins

Heavy snow & severe t’storms…just like spring!
February 19, 2009

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Low pressure tracking from the great lakes toward New England tonight, produced a March-like wintry mix of snow, sleet and rain around here today.  Officially, just 0.2″ of snow at BWI-Marshall, but this same storm system will dump much heavier amounts of snow on areas just northeast of here.  From the Poconos to the Catskills to the Adirondacks, Green and White mountains, 6-15″ of snow will be possible tonight and early Thursday.  The main area of low pressure is expected to redevelop on the New England coast Thursday afternoon, prolonging the snowfall for the colder sections of New England.  To our south, the cold front has been triggering severe thunderstorms, with tornado watches posted this evening in parts of Mississippi, Alabama and Georgia.

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The same front will sweep across Maryland Thursday with gusty winds, falling temperatures and possibly a few more snow showers.

Tom Tasselmyer

A Blockbuster Storm
February 15, 2009

It is hard to forget this storm. Back in 2003 18-25 inches of snow fell across the region over a four day period. Below are the particulars as measured at BWI-Marshall.

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Note: Here are links to four WBAL-TV videos from Feb. 2003:
Jayne Miller Reports From Downtown
Roads A Mess After ’03 Storm
Rob Roblin In Harford County
Lisa Robinson On Damage To B&O, Other Buildings