930PM SAT 1 JAN UPDATE ON JAN 3 WINTER STORM FOR LOWER MID ATLANTIC
1 GUESS MAP RELEASED12AM
The midday JAN 1 radar shows widespread significant heavy rains and thunderstorms stretching from central and eastern Arkansas and northern Mississippi into western and central Tennessee, western and central Kentucky, southeast Missouri, southern Illinois, the southern half of Indiana, all of Ohio, and into western Pennsylvania. There is also moderate to heavy snow in much of Iowa, northern Illinois, southern Wisconsin, and western Michigan.
So far the forecast has worked out exactly as I have been saying for the past week. It has been extremely warm but the pattern change IS here and it is going to hit with force. At midday on January 1st there are numerous tornado watches across portions of Arkansas, Mississippi, and Tennessee, and Kentucky. Additional severe thunderstorm watches and tornado watches are likely to be issued over the next 12 to 18 hours as the strong arctic cold front moves out of the Plains and pushes into the Ohio Valley and the Deep South over the next 36 to 48 hours.
This NEW arctic cold front will even help more as it will produce widespread significant rain of 1–3 inches in West Virginia, the Carolinas, northern Alabama, northern Georgia, Tennessee, and Kentucky, and as much as 2 inches of rains in western Virginia and western and central Maryland.
The rain in West Virginia and eastern Kentucky will move into eastern Tennessee, western Virginia, western Maryland, and western North Carolina during the next 6 to 12 hours, and the rain will be heavy at times overnight. There may be a break on Sunday afternoon when not much is happening but then everything goes sideways as the weather models are now in very strong agreement that a major area of LOW pressure is going to develop on the cold front in Georgia and Alabama on Sunday night into Monday morning.
12z GFS SNOW DEPTH TOTAL
The second area of intensifying LOW pressure is going to pull down the cold air from the Great Lakes into Tennessee, Kentucky, western North Carolina, and southwest Virginia late Sunday night and early Monday. The rain will change to snow and it will snow heavily in these areas for several hours Monday morning. Snow accumulations will range from 2 to 6 inches, depending on elevation and the ground temperatures which are still quite warm. If we were in a regular winter pattern this developing LOW pressure area in Georgia would produce up to a foot of snow in the mountains of western North Carolina and into Southwest Virginia.
The LOW will track across North Carolina and continue to pull in colder air so that the rain will change to snow with possible significant wet snow accumulations in central and interior eastern Virginia including Richmond, the Middle Peninsula, the Northern Neck and the southern half of the Delmarva. There could even be accumulating snow Monday morning to midday in Greensboro North Carolina, Danville and Emporia.
Again, IF he ground temperatures were not warm and surface conditions were not wet from the previous rains, this would be a 6 to 12-inch snowstorm for much of central and eastern Virginia. However, since that is not the case these areas are looking at anywhere from 2 to 5 inches of snow mostly on the coldest services such as trees, grassy Lawns, car tops, the back porch, etc.
There is of course some uncertainty as with all Coastal storms and especially with one which features rain changing over to snow in a mild pattern. Even with the cold air arriving in the early morning hours of Monday, the key will be how heavy the precipitation will come down Monday morning to midday in southwest, central, and east central Virginia and into the north side of Hampton Roads.
**KEY POINT *** when the precipitation comes down heavy like the models or depicting it keeps the atmosphere near the ground cold enough so that the snow can accumulate at 32 or 33 degrees. As you can see many of the 12z SATURDAY models are showing 2 to 8 inches of snow central and interior eastern VA into the Delmarva but this is overdone because of the warm ground conditions and the recent rains from Sunday night.
The other issue will be the northern extent of the snowfall. Undoubtedly the rain will change to snow across a good portion of the Shenandoah Valley, northern Virginia DC Baltimore, and the northern Virginia Piedmont. But the intensity of the snowfall will not be heavy enough to cause any accumulation and it will probably melt on contact.
Behind the system, the cold air moves in and it moves into stay at least for a few weeks. A strong reinforcing cold font arrives on January 6–7. A wave of LOW pressure is expected to develop on this front. Earlier, the data took this LOW up into the Ohio Valley and the eastern Great Lakes which would pull up mild air into the Middle Atlantic region and the central Appalachians for a day or two. However the new data shows the LOW pressure area taking a track further to the east so it looks like rain and snow for the central Appalachians going over to all snow on January 7th, followed by a blast of Arctic air.
OUTLOOK MAP FOR JAN 3 .. this is a bit under done?
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As I mentioned on the Twitter page…. the operational Saturday 18z GFS, as well as the 18z GFS Ensemble have gone absolutely Bonkers with the storm developing a massive snow shield with heavy snow in all of Virginia except for the far Northwest areas with significant accumulations as far north as dc-baltimore into southern New Jersey and heavy snow in North Central and Northwest North Carolina as well as Southwest Virginia.
This is of course way overdone but even the 18Z GFS ensemble is significantly snowier with a better more organized snow shield. In addition, the 18z EURO which has dramatically increased its now shield and snowfall amounts when compared to earlier today. For this reason my initial Outlook math is probably too conservative
… The FIRST GUESS map which will be out at 1 a.m.