Light Snowfall Ending

A Winter Weather Advisory remains in effect for far eastern Virginia this morning, where light snowfall is still falling at 5 a.m. The overnight snow left accumulations of less than an inch in Central Virginia, with most places receiving only a dusting. Roads this morning are wet in most places, but not snow-covered, as ground temperatures remained just above freezing most of the overnight period.

Snowfall Update

Light to moderate snow is now falling across much of central Virginia. Temperatures are currently a few degrees above freezing, so accumulations will be slow to occur. Snow is developing across southwest Virginia near Roanoke, and I expect that area of snow to move into central Virginia in the next few hours.

Weather Update - 4:37 PM

Winter Weather Advisory has been issued for communities to the east of I-95. We are still expecting a dusting to an inch of snow for the entire area for tonight.

Cold Air Diving Southeast

The second blast of cold Canadian air is making swift progress southeastward early Thursday morning behind the low pressure system currently tracking through the Midwest. Here is the pre-dawn surface map for the U.S.:

Wind Chills in the Plains are dangerously low this morning as high pressure from Canada continues to dive southward with gusty northerly winds:

Light snow is expected to move into Virginia after dark Thursday, first affected western parts of the state, then overspreading the rest of Central Virginia around 11 p.m. Because of limited moisture availability and the swiftness of the upper-low, only minor snowfall accumulations are expected through Friday morning. However, 1" to 3" will be possible in western parts of the state, where a Winter Weather Advisory has been issued.

Cold Plunge Continues

A new storm system is tracking through the Plains Wednesday, ushering in another cold Canadian airmass that will overtake the U.S. east of the Rockies through the end of this week.

This means much of the country that has already been in a deep freeze for about a week will still be abnormally cold at least until early next week. This is an unusually extended period for such cold weather in the Deep South and Florida, where yesterday's highs were only in the 50's in most places!

Record cold low and high temperatures have been set in Florida in recent days. Here are some of those reports:

Record Cold Highs Tuesday, January 5, 2010:

Orlando, FL 47 degrees

Melbourne, FL 50 degrees

Vero Beach, FL 52 degrees

Naples, FL 55 degrees.

New Record Lows Wednesday, January 6, 2010:

Tampa, FL 27 degrees

Melbourne, FL 27 degrees

Daytona Beach, FL 28 degrees

Vero Beach, FL 28 degrees

Orlando, FL 31 degrees

Fort Myers, FL 34 degrees

West Palm Beach, FL 34 degrees

Naples, FL 35 degrees

Miami, FL 40 degrees

In the Great Lakes region, nearly incessant Lake Effect Snow has produced high snow totals over the past week:

Upslope snow showers have also been continuous along the Appalachian Mountain chain the past week. The snowstorm now diving through the Plains today will add up to 9" of snow in the Midwest, on top of the plentiful snowcover currently in place.

Central Virginia still looks on track to get about an inch of snow Thursday night into Friday morning as a result of this approaching upper disturbance. Some locations may only get a dusting, while others may get more than an inch. Moisture still appears to be quite limited for our area while the system tracks through, but any snow that does fall will stick.

Unseasonably Cold Temperatures

Unseasonably cold weather will linger through the weekend into next week as a result of the deep low pressure trough stationed over the eastern half of the U.S. The image below is a view of the upper trough looking down onto the Northern Hemisphere, showing the source region of the trough in Canada all the way into the Southeast U.S.:

This means cold air continues to plunge into the northern Plains and upper Midwest from north-central Canada. While modification of the Canadian airmass does occur as it moves southeast, it is moving over a lot of snowcover, which helps keep the air cold.

Streamlines show us how the air is moving, and you can see a stout flow from the upper Midwest over the Appalachian chain into Virginia. That means cold Canadian air is plunging into the Midwest over snowpack, over the mountains and into the Commonwealth.

Storm tracks will follow a similar path as they dive into the Plains from Canada and head eastward. Our next upper disturbance will plunge south Wednesday into the Plains, then head toward the East coast late Thursday and Friday, producing a quick light snowfall across the region. In Central Virginia, only minor snowfall accumulations are expected, generally from a dusting up to an inch as a result of limited moisture availability.