NEXT UP-MARCH 25 WVA/ southwest VA/ south central VA SNOWSTORM
STARDATE 201803.21 1500 EDT
As some of you may have heard me mention earlier on videos... on the website and on the Facebook page.... there is ANOTHER threat which is coming fast and poses the serious threat of a significant snow for
- the southern half of west Virginia
- the southern half of the Shenandoah Valle
- all of southwest Virginia
- the southern Virginia Piedmont into the Richmond metro area and perhaps into INTERIOR Hampton roads
perhaps some of northern counties of North Carolina.
After this coastal storm / noreaster leaves on Wednesday night / Thursday morning a large arctic HIGH will move into Eastern Canada just north of the Great Lakes. This Arctic HIGH will bring Much Below Normal temps over all of the Midwest and Northeast US. This HIGH will force the next system coming out of Chicago Iowa and Indiana to take a southeasterly track.
Yes Saturday Max temperatures across much of Virginia will be between 38 and 46° Sunday .. with 30s across West Virginia and southwest Virginia.
The KEY will be the low DEW POINTS and the North winds which will ensure that whatever precipitation falls Saturday night and into Sunday it will be snow.
For example Richmonds forecast Max temperature on Saturday may be 44-46° but the dew point will be 23. This means that when the precipitation starts on Saturday night temperatures will quickly collapsed down to 30-32° . In southwest Virginia on Saturday morning the dew point may be below 20 which is really cold and dry air for mid and late March. So in other words if you have a temperature 45° but your dew point is 35° you will saturate and around 38° and you have rain.
BUT ...if you have a temperature 45° with a dew point is 22 you will saturated around 31-32° which is snow.
There are in essence 3 possibilities / scenarios for consideration.... And all three have to do with the TRAJECTORY of the significant /heavy snow.
This system Saturday night into Sunday COULD bring anywhere from 3 to 10 inches to Roanoke ...Blacksburg ...Wythville ....Martinsville ...Lynchburg ....Lexington ...Charlottesville... Farmville ....Blackstone ...Richmond ....Petersburg ...South Hill.... Lake Anna ....Hanover.... into Charles city and possibly into locations such as Stoney creek and Emporia.... DEPENDING ON THE TRAJECTORY !!
As the snow comes east over the mountains ...it will begin to break apart so the snow amounts east of Richmond will fall off significantly. Based upon the current data it looks like the best snow will be over southwest third of Virginia.
This image shows the 3 different scenarios for your consideration.
NUMBER 1 has the best snow hitting southwest Virginia into northwestern and north central North Carolina staying to the south and west of Charlottesville / Lake Anna / Richmond.
NUMBER 3 has the heavy snow than shifting north a little bit which could bring the snow into portions of northen Virginia south of Interstate 66 and possibly into areas north of Charlottesville and Fredericksburg.
In ALL three scenarios again it looks like the areas in southwest Virginia including all of the Roanoke metro area Lynchburg Lexington would see the best snow has the potential for 8 inches or more Saturday night into Sunday morning.
2ND KEY POINT .. the snow GRADIENT with this event will be very tight. A difference of 25 miles could mean 4" or 0.0"
Besides the actual trajectory of WHERE the heavy snow areas will be ... HOW the heavy snow crosses over from West Virginia into the commonwealth of Virginia ...the other issue is how much of the snow gets ripped apart crossing the mountains of West Virginia. Typically that does happen when you have significant precipitation coming in from he Ohio Valley. So that is something to watch out for.
On the other hand we do have a large arctic HIGH to the north and a decent of LOW pressure coming through Tennessee and Kentucky. The interaction of these two features will do bring in a low level easterly jet which will aid in moisture and in the development of dendrites and snowfall production.