Radiational Cooling:  The cooling of the Earth's surface. At night, the Earth suffers a net heat loss to space due to terrestrial cooling. This is more pronounced when you have a clear skies, calm winds and dry air in place.  (NWS definition)

Wednesday morning lows fell into the low to mid 30s.  Many areas were close to records and Lynchburg broke the old record. (See Graphic)

As the high builds off the Southeast coastline temperatures by late week will quickly climb.  Look for highs in the 80s by Friday.

You may be asking yourself... Why does a upper level ridge of high pressure bring warmer and usually drier weather??? An upper level ridge is nothing more than an elongated area of high atmospheric pressure. It occurs both at the Earth's surface and at higher altitudes. Air tends to sink under a ridge, which inhibits clouds and precipitation development. As air sinks it also warms up.  Therefore temperatures are usually warmer when a ridge is overhead.

As we head into the weekend the ridge will break down, allowing a cold front to arrive.   This will bring us a good chance of showers and thunderstorms (especially Saturday afternoon).  This front looks to cool us down and keep things on the unsettled side for least the first half of next week.

Forecasting beyond 6 or 7 days, admittedly, does not have a very high success rate. However, there occasions in which we see patterns developing in the weather, particularly at the jet stream level, that can point to general trends in the weather up to 2 weeks in advance.

As you would guess, confidence in any forecast goes down the further in advance the forecast is made, but one of the things we’ve noticed in the last few days is that there does not seem to be any very warm air developing over the Continental U.S. through the end of March. Although there may be a day here or there where we get into the 70s, we will likely have to wait until the first week of April (at least), before we can string together a 2-or-3 day stretch where it is dry and temperatures are in the 70s.

With that in mind, below is the general thinking about the weather for the next couple of weeks. Enjoy!

Sean Sublette

Forecast made at

8am Friday, March 21, 2008

Friday: Mostly sunny, warmer, and much less windy. High 64.

Friday night: Partly cloudy. Low 43.

Saturday: Intervals of clouds and sun with an isolated shower or two. High 63.

Easter: Mostly sunny, but chilly. Morning temperature near 30. Afternoon high 53.

Monday: Mostly cloudy with a few showers. High 46.

Tuesday: Mostly sunny. High 51.

Wednesday and Thursday (3/26-27). Mostly sunny. Highs in the 60s Wednesday, near 70 Thursday.

Rain likely Friday (3/28). Highs in the 50s. 

Dry Saturday (3/29). Highs in the 60s.

Showers Sunday (3/30). Highs in the 50s.

Dry early next week (3/31-4/2). Highs in the mid 50s to mid 60s.

Average (aka normal) temperatures for late March:

Highs in the upper 50s to lower 60s, lows in the middle-to-upper 30s.

That is the question everyone is asking. Well it looks like this winter will go into the record book as another winter with below average snowfall totals. Now that we are heading toward the middle of March, snowy weather chances drop significantly.

So what happened this year? We had cold enough temperatures at times and periods of stormy weather, but never the perfect setup. For most of the winter the storms tracked from the Gulf Coast through Tennessee, Kentucky, West Virginia and into New England. This pattern nearly always brings us wet weather, as warm air from the Gulf and Atlantic is pulled into Virginia ahead of the area of low pressure to our northwest. At times there was just enough low level cold air in place to see an ice to rain mix, but never cold enough for a true snowstorm.

What is the perfect setup? Our best snowstorms usually occur when a cold area of high pressure moves in from eastern Canada and sits to our northwest over Ohio and Pennsylvania. At the same time a strong area of low pressure develops along the Gulf Coast and moves northeast across northern Georgia into central North Carolina and through eastern Virginia. This would bring us plenty of Gulf and Atlantic moisture and would continue to wrap in cold air from the north. This pattern would guarantee a winter wonderland and several snow days to enjoy 6 to 12 inches of the white stuff.

Matt Ferguson

Meteorologist

This Wednesday evening, February 20th, a total lunar eclipse occurs. The problem we will have -- scattered clouds may obscure our view!  At this time a weak disturbance should move through the region Wednesday, bringing mostly cloudy skies. As the evening unfolds it looks as though the clouds will be in the process of clearing across Central Virginia. Hopefully this process has kicked in before the eclipse gets underway.

Total Lunar Eclipse Details:

At 8:43pm the full moon (in the eastern sky) begins to pass through the shadow of the earth. By 10:01pm total eclipse will occur turning the moon a beautiful shade of red. The moon begins to emerge from earth’s shadow at 10:51pm. Eclipse ends at 12:09am Thursday. This will be the last one until December 2010.

For more information about the upcoming eclipse visit this website...

http://shadowandsubstance.com/

For more information about a lunar eclipse visit this website...

http://www.mreclipse.com/Special/LEprimer.html

Matt Ferguson

There are 3 opportunities for significant snow or ice between now and the end of the month.

The first chance comes Wednesday morning (2/20), as a weak storm moves in from the northwest.  It looks like the temperatures will be low enough to support snow, but when these systems come from the northwest, they are quite moisture starved by the time they arrive.  So even though some snow showers are a distinct possibility, an accumulating snow is not likely.

The second storm comes in the window between Friday morning (2/22) and Saturday morning.  There are some big conflicting signs with this storm as to what the ultimate precipitation type will be and how much will actually fall.  The early guess is that we will have some ice, then see a change to rain long before the precipitation comes to an end.  However, confidence is very low with this system, as most of our significant snow storms come as the center of low pressure tracks to our south and this is the way many of the computer simulations are portraying the storm track Monday morning.

The third storm comes along about Wednesday of next week (2/27).  When we look at storms that far in advance, the particulars are nearly impossible to determine, however, the storm's center looks as if it will go by just to our west, suggesting light ice quickly changing over to rain.

Sean Sublette

Meteorologist

Tuesday night 2/5/08 into Wednesday 2/6/08 the deadliest cluster of tornadoes in nearly a decade tore through five Southern states. At last count the death toll was up to 50. So you may be asking yourself how common are winter tornadoes???

Well the peak tornado season runs from late winter through mid summer, but twisters can spin up at any time of the year with the right conditions. We had the perfect setup for tornadoes across the Mississippi River Valley Tuesday night. A large high pressure system off the Southeast coast brought the region unseasonably warm and moist air for February (Central VA saw record highs in the 70s). At the same time a strong cold front pushed in from the upper Midwest. This sparked off a line of severe thunderstorms. In addition the contrast between the cold air to the north and warm air to the south triggered a fast moving jet stream above the storms. This introduced wind shear (changing wind speeds both in the horizontal and vertical directions), which caused the thunderstorms to rotate. Rotating thunderstorms are called supercells and these storms typically produce the most violent tornadoes.

According to the Storm Prediction Center in Norman, OK Tuesday night’s outbreak was the nation's worst in a 24-hour period since May 3, 1999. The death toll ranks among the top 15 from tornado outbreaks since 1950. This serves as a reminder of how dangerous tornadoes are.

When tornadoes are possible in the viewing area, ABC 13 will be the first to let you know. Remember a tornado watch means tornadoes are possible, therefore continue to monitor the potential for severe weather. If a tornado is detected on radar or is spotted, a tornado warning is issued. In case a tornado warning is issued for your community - take cover immediately. Go to the basement and protect yourself using pillows and blankets under a sturdy table. If you have no basement, go to a bathroom or closet, with no windows.

Matt Ferguson

Meteorologist

mferguson@wset.com

The storm that arrives late tonight looks to produce a lot of precipitation, but even with temperatures below freezing, no snow is expected.

As the storm approaches from the south, the winds between 2,500 and 4,000 feet will also be from the south, bringing tremendous amounts of warm air in.  Temperatures at that altitude will be between 40 and 50 degrees during most of the storm.  Down here at ground level, the wind does not look to be as strong, and the direction of the wind will be much more from the east (or even northeast to start).

So, as snow falls into that warm layer from above, it melts into rain.  That rain then freezes on surfaces upon contact, and produces a glaze here at the ground.

The worst travel period with the storm will likely be between 5:00am and 10:00am Friday.  As the morning goes on, the precipitation intensity will also pick up, but we are optimistic that temperatures will begin to climb above freezing by midday.  Even with the sky cloudy, there should be enough energy from the sun getting through to allow pavement temperatures to creep above the freezing mark, although many elevated surfaces (power lines, decks, cars, pine needles) will still have a crust of ice on them.

Once the storm passes, the weekend looks nice: dry with afternoon highs in the 50s.  Beyond the storm Friday, we see another chance for rain in the Tuesday night to Wednesday window.  Temperatures will then be closer to normal towards the end of next week, but no bitter cold looks to break into the state for about another 10 days.

Sean Sublette