Archive for October, 2008

Snow is back!
October 28, 2008

It’s not even Halloween yet, but western Maryland is under a Winter Weather Advisory tonight. At Garrett College in McHenry, the high temperature today was just 30F, the low so far 28F. The strong storm that tracked from the coast of New Jersey north into central New England has produced a strong northwest wind across all of the mid Atlantic region. This northwest flow of air is drawn down from the great lakes where the moisture laden air rides up the western slope of the mountains producing “lake effect” rain or snow, depending on the temperatures. With the cold air in place, the lake effect tonight will produce snow, possibly 3-5″ overnight on the highest ridges. The pictures posted here are from the Maryland State Highway Administration’s camera on Big Savage Mountain, elevation 2,454 feet. The first picture at 5:14pm Tuesday shows some snow on the grassy shoulders but just wet pavement. By 11:12pm Tuesday night, with the temperature at 29F, the snow is starting to stick to the road.  The gusty winds and colder than normal air will continue to buffet Maryland on Wednesday and it’s even possible that a snowflake or two could cross the mountain ridges and arrive in the colder suburbs north and west of Baltimore. For those not ready for winter just yet, hang in there…sunny, milder weather is coming for Thursday and Friday.

Tom Tasselmyer


Monday Update
October 27, 2008

Well, the cold front moved through today and it carried a bit more moisture with it than anticipated, generating generally less than a tenth of an inch of light rain and drizzle today into the early evening hours Monday. The cloud deck was persistent all day and the lack of sun held the temperatures down. When the rain moved in about midday temperatures dropped from the low 50s into the 40s and never recovered.

Over the next couple of days the influx of cold air and an offshore disturbance will conspire to produce breezy conditions, a mix of clouds and some sun and a chance for a period or two of sprinkles or brief rain showers. A mix of rain and some snow is possible in the mountains.

NOAA Water Vapor Satellite Image … Monday Afternoon

The satellite image above clearly outlines the upper air “trof” of low pressure that is advancing on the eastern seaboard.

NOAA NAM Forecast Model for Tuesday Afternoon

The forecast map above shows the forecast storm position early Tuesday afternoon with the rain shield beginning to move to the northeast. The blue line that dips into northern Florida is the freeze line for temperatures at the 850 mb level ( approx. 8,000 feet around Baltimore ). Winds are northerly at that level and that is why the temperatures have fallen. The blue line roughly approximates the outline of upper air “trof” that shows up on the satellite image near the top of this article. At an altitude of 11,500 feet ( 750 mb level) the winds are blowing from a south-southwesterly direction and those are the winds that will push the storm away from the area during the day Tuesday, reducing the rain chances.

By the middle to end of the week, temperatures should begin to moderate along with a reduction in cloudiness as the entire upper air “trof” drifts to the northeast.

John Collins

Weekend Wrap-Up
October 27, 2008

This weekend was really a split decision. Saturday a washout and Sunday was terrific.

Saturday’s rainfall broke a 23 day dry spell at BWI-Marshall. The airport received .72 inches of rain bringing the month’s total to .84 inches. Other locations in the region measured 1 to 1.5 inches. Despite the rain, the month will probably end in a deficit at the airport. As of Sunday the rain total is 1.82 inches below the 30 year average.

A cold front will be moving across the Mid Atlantic region Monday, probably rain free. Much colder air will filter in behind the front though, driving temperatures below average.

An upper air low pressure system will be parked just to the north and will keep the cold air flowing for several days. Upslope flurries or snow showers are possible in the Maryland, Pennsylvania and West Virginia mountains. A few sprinkles wouldn’t be out of the question closer to the Bay on Tuesday and Wednesday.

John Collins

Weekend Storm
October 25, 2008

A storm is on the way that will dramatically increase the rain chance for the first half of the weekend. The timing of the storm may be questionable as far as affecting weekend activities but it is not all bad news.

October has been a dry month with only .12 inches measured through today, leaving a shortfall of 2.36 inches for the month. If not for the heavy rains at the end of September, the area would be in a much more profound drought situation.

The storm forecast for Saturday has the potential to make up for at least half of the month’s shortfall.

The graphic above shows the forecast rain totals for Saturday afternoon. The northeast corner of Maryland is on tap to receive as much as 1-1.5 inches of rain in that time period. Of course the rain will start in the predawn hours of Saturday and will likely extend into at least the early evening so higher totals are possible.

The cold front and low pressure center associated with the storm will be approaching the Bay Saturday afternoon and will be east of the entire state by Sunday when northwest winds out of the mountains will dry the atmosphere and allow the sun to hold temperatures in the normal range for the season. A secondary cold front will sweep through the area Monday and unseasonably chilly temperatures will dominate the rest of the week.

John Collins

October Blizzard!
October 22, 2008

It’s not even halloween yet, but blizzard warnings have been posted for northwest Kansas and southern Nebraska.  Deepening low pressure over Kansas is expected to draw in colder air today, changing rain to snow with 3-4″ around Goodland, KS and upwards of a foot of snow near McCook, NE by Thursday evening.  As the storm intensifies the wind across this part of the plains is forecast to increase to 30-35 mph with gusts to 45 mph, creating whiteout conditions on I-70 and considerable blowing and drifting of snow.  As this storm moves east it will draw warmer air northward from the gulf coast region and bring a chance for rain here in the mid Atlantic region this weekend.

Tom Tasselmyer

First Freeze
October 20, 2008

In the early morning hours on Monday, clear skies, a lack of wind and dry air allowed temperatures to fall within range of freezing across the region. The BWI-Marshall 8:00am observation reported a temperature of 32 degrees. This was an “hourly” reading and the actual low may be a degree or two colder. The official low will be announced Monday evening.

Most of the “hourly” lows across the region were in the low-mid 30s, cold enough to indicate that frost and freeze conditions were likely widespread. The exceptions were locations that are near the Bay and in densely populated urban areas where lows were recorded in the 40s.

The growing season has probably ended in many areas as temperature sensitive plants were nipped by the frost. This fact may take  a little pressure off of the fact that the area is short on rain. The last significant precipitation was at the end of September. Only .12″ of rain has been measure at BWI-Marshall in October. With no rain in today’s forecast, that will put the area almost 2 inches behind the 30 year average.

While the growing season may have ended, the dry conditions and leaf fall bring a risk of wild fires. A weak cool front will cross the area Tuesday and will, by and large, be dry. It will become windy after the front passes and this will increase the risk of the spread of any fires that may start.

On last Sunday’s “Sunday Gardener” Carrie Engel and I made mention of the fact that it is important to water newly planted shrubs as winter approaches. Even if a newly planted shrub is going into dormancy, the roots are getting established and need adequate water. The recent dry conditions make watering all the more important for the successful overwintering of new plantings.

Some rain relief may be in sight. At the end of the week a storm system is expected to develop along coastal areas of the Mid Atlantic region.

NOAA GFS Computer Forecast Model Saturday, Oct 26

The image above shows one computer forecast for the positions of weather systems on Saturday. If this model is on track it shows that this developing storm is the best shot at rain that the area has had since the end of September.

John Collins

New National Weather Service Office Open House
October 16, 2008

The National Weather Service office that has responsibility for the Baltimore/Washington area has opened a new facility near Dulles Airport in Sterling, Virginia. The move to a new facility was required to make way for a new runway at the airport.

The state-of-the-art facility includes a new Doppler Radar (tower and dome on the left) and new weather balloon launching and tracking unit (dome on the right).

The main forecast office includes the latest technologies utilized by the National Weater Service.

The National Weather Service will be holding an open house this weekend, Saturday from 9:00am-5:00pm and Sunday from 12:00n-5:00pm. The official dedication will take place at 1:00pm Saturday.

Activities are planned for the whole family with tours, demonstrations and hourly weather balloon launches.

The address is 43858 Weather Service Road, Sterling, VA 20166. The entrance to the Weather Service grounds and access to Weather Service Road is on Old Ox Road (VA 606) on the north edge of Dulles Airport.

For more information on the open house check the National Weather Service web site

By the way, the weather looks favorable.

John Collins

Thursday Tropics
October 16, 2008

Hurricane Omar passed east of Puerto Rico overnight and is moving northeast out into the Atlantic.

NOAA Visible Satellite Image

The remnant of Tropical Depression 16 has moved inland in the vicinity of Honduras, Guatemala and Belize (lower left in the picture above).

For more on the tropics check our Hurricane Tracker …

John Collins

Omar On The Move
October 15, 2008

Hurricane Omar is making it’s move on the Northern Leeward Islands of the Caribbean.

NOAA Enhanced Satellite Image

Early Wednesday afternoon, Omar was 195 miles southwest of St. Croix, moving east-northeast at 13 mph. Hurricane hunter aircraft have determined that Omar’s maximum sustained winds are 85 mph, making the storm a category one hurricane.

Omar is expected to track across the Virgin Islands in the next 24 hours and hurricane warnings are in effect for that part of the Caribbean.

Meanwhile, Tropical Depression 16 is tracking westward along the Honduras coast and may briefly reach tropical storm strength before making landfall.

NOAA Satellite Image

For tropical updates check our Hurricane Tracker at

John Collins

California Fires
October 15, 2008

Wildfires in southern California are in the news again. The satellite picture below gives you a sense of the scope of the fires.

NASA Satellite Image courtesy of and enhanced by StormCenter Communications

The satellite picture shows the smoke being blown in a southwesterly direction, away from the fires. The length of the smoke column is an indication of how strong the winds are. The strength of the Santa Ana winds fanning the fires is determined by the atmospheric pressure change (gradient) on either side of the southern California mountains.

StormCenter Communications provided the following information on the fires.

The above MODIS image captured on October 13, 2008 shows the Sesnon Fire and the Marek Fire burning about 25 miles northwest of Los Angeles, California.


Additional Information:


  • As of October 14, 2008, the Sesnon Fire has burned 7,000 acres and is 0% contained.  The blaze has destroyed 19 structures and it is unknown how many of those are houses.
  • As of October 14, 2008, the Marek Fire has burned 4,726 acres and is 5% contained.   The blaze has destroyed 44 structures, 39 of which were houses.  The Marek Fire has forced the evacuation of 1,800 people.
  • Gov. Schwarzenegger has declared state of emergencies in Los Angeles and Ventura Counties.
  • Santa Ana winds are a California firefighter’s nightmare. These blustery, dry, and often hot winds blow out of the desert and race through canyons and passes in the mountains on their way toward the coast. The air is hot not because it is bringing heat from the desert, but because it is flowing downslope from higher elevations.
  • As fall progresses, cold air begins to sink into the Great Basin deserts to the east of California. As the air piles up at the surface, high pressure builds, and the air begins to flow downslope toward the coast. When winds blow downslope, the air gets compressed, which causes it to warm and dry out.  Not only do the winds spread the fire, but they also dry out vegetation, making it even more flammable.
John Collins