POSSIBLE WINTER WX / SNOW EVENT WVA VA MD DEL NOV 30
For many of these areas this will be the first snow the season while for other locations.. this will be the second snow of the season. This is a tricky situation because the system is not being handled well by the various weather models. However as we get closer to November 30 the weather models are showing the system with a bit more clarity with each new model one. In other words as we get closer to November 30 the system appears slightly stronger and better organized with each new weather model cycle.
Here is 6z GFS from Friday morning and as you can see it showed NOTHING for NOV 30th but the new and improved GFS FV3 much more " aggressive" with the Upper air energy. In January 2019 the experimental GFS FV3 model will replace the current or regular GFS model which is a vastly inferior model. The research and testing shows that the GFS FV3 is a significant improvement. The data shows that this new version of the GFS model is almost as good as the European model.
After a significant LOW pressure area moves through the Ohio Valley and then jumps to the New England coast on Monday November 26... that LOW will become a monster system over southeastern Canada. This in turn will allow for a powerful Arctic air mass to be unleashed across the eastern half of the country.
Temperatures across the middle Atlantic region will turn progressively colder each day on November 27...28 ...and 29.
The morning Min temperatures on the 28th and 29th will drop into the Teens over eastern Western Virginia... western Maryland ...portions of the Shenandoah Valley... southwest Virginia and the mountains of North Carolina. Over the Piedmont and central sections of North Carolina/ Virginia / Maryland readings will get into the low to mid 20s. The model data shows that on the morning of the 28th and the 29 there will be a large arctic HIGH pressure system over the Great Lakes and New England keeping the cold air in place.
This next map shows the upper air disturbance which is going to develop the possible winter system for November 29 and 30th. Last week the weather models show the system being crushed or suppressed by the large Upper Low over southeastern Canada. With the Upper r level energy gone ...any precipitation or LOW pressure area will rapidly fall apart as it crosses Missouri and Tennessee. However as you can see on this map the NEW data is showing this system is fairly strong
As a result ...it will develop a wave of LOW pressure over Tennessee on the 29th of November. With the cold air in place the precipitation will fall as snow over portions of Ohio... far northeast Kentucky ...central and southern portions of West Virginia ... northwest corner of North Carolina ...southwest Virginia and the Shenandoah Valley on the morning of November 30.
If the precipitation comes down hard enough temperatures will stay around 30-32° for most of November 30 and the snow will spread into central Virginia reaching Fredericksburg and Richmond. Because the days leading up to NOV 30 will be quite cold for late NOV.... any snow or Ice that falls will / should stuck
The potential exists for least a few inches of snow over the colder areas such central and southern portions of West Virginia ... northwest corner of North Carolina ...southwest Virginia and the Shenandoah Valley . The data suggests there COULD be some small accumulations of an inch or two over portions of the Virginia Piedmont and possibly up to 1 inch --if it stays all snow --in places such as Ashland Fredericksburg and Richmond.
The snow could reach as far north as Washington, DC but since the system is weak and does not have a lot of upper level energy... the snow shield might not make it to Washington, DC/ Baltimore or just fall as flurries or snow showers.
The new 18z GFS modelas turned much wetter with this system for NOV 30 and Iis ow has a solution similar to the GFS FV3
WHAT CAN GO WRONG?
Right now the main weather model data showing this sort of light to moderate snow event on November 30 is the FV3 GFS model. The European model still does not show anything significant because the upper level energy gets crushed as it crosses Tennessee on November 29. That is still a possibility and this whole system might fall apart.
Temperatures do appear to be cold enough at the surface and Low and middle levels of the atmosphere to support all snow at least thru midday on November 30.
Right now this does not look like a big deal. And given the overall pattern and the fact that the upper level energy is trying to survive as it moves into North Carolina and Virginia... the odds strongly favor that it is not going to become a big deal. Given the middle and upper level pattern there will be a sharp cut off in the snow shield to th north somewhere across far Northern Virginia or Maryland.