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A major snowstorm? Just find the line…

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Posted at 10:12 AM, Jan 19, 2016
and last updated 2016-01-19 11:07:24-05

When it comes to our chances for a “major snowstorm” later this week… we are on the line. The rain/snow line will play a HUGE role in what we see on Friday and Saturday.

Note: We are still several days away from this event. Not every forecast answer is available or reliable at this time.  As we get new forecast information, expect the forecast to be fine tuned and changed as need be over the next several days.

The Set Up

VIPIR Fri AMVIPIR Thu PMVIPIR Fri PM

An area of low pressure will move into the Mid-West by Thursday and begin to move east into the Southeast. In the first image you can see it over the Mississippi River midday Thursday. By Friday this low will make a slight NE turn and head into the Mid-Atlantic. Image two is Friday morning. By Friday evening (image three) precipitation covers most of the Mid-Atlantic. By Saturday the low is off of the VA/NC coast and moving up toward the New England states. The counter clockwise flow around the area of low pressure will bring moisture up from the Gulf and eventually the Atlantic. At the same time another push of cold air will slide SE from the Great Lakes. You know the equation… Moisture + Cold = Snow. The biggest question for us will be, how far south and east will that cold air extend.

Rain vs SnowVIPIR Fri PM2

The rain/snow line will be the key to this forecast. If the line shifts west/north, we see more rain(or even all rain). If the line shifts east/south, we see more snow. Here is a snapshot of VIPIRcast from Friday evening. Notice the area of pink, that is the mixed precipitation, “the line”. It stretches from the northern Eastern Shore to Williamsburg to Emporia. Expect that line to move as the area of low pressure moves through Friday and Saturday.  We have a chance to see all types of precipitation across Hampton Roads and Northeastern North Carolina.

How much snow?Euro Snow

It it still too early to nail down snowfall specifics. But this system does have one thing going for it… a lot of moisture. That could mean a lot of rain or a lot of snow. It all depends on the location of that rain/snow line.

GFS SnowI have included two of our long range forecast model snowfall forecasts (the GFS and ECMWF).

NOTE #1: Expect these to change over the next few days.

NOTE #2: These are computer model outputs. One run, one image… not absolute truth.

A few things to notice… Look at how closely spaced the bands are near Richmond. That is an indication of where “the line” will spend the most time. Look for the stripe of purple, that is ~12″ of snowfall. The light blue is ~1″. So between Norfolk and Richmond (or just west of Richmond) both of these computer models have a range of snow from 1 inch to 1 foot. Hence, why that rain/snow line will dramatically shape our forecast.

Bottom LineSnow_Sat

If the current forecast holds we will likely see major snow accumulations (double digits) in parts of Virginia. As of now, it looks like those big totals would stay to our north and west. These images are from NWS/NOAA and show the probability of seeing over ~2″ of snowfall. Notice the 90% chance (red) in northern VA, MD and north.

Snow_FriCould some of us just see rain? Yes

Could some of us just see snow? Yes

There is still a wide range a precipitation possibilities. One of the many challenges of being on “the line” with these types of winter events.

Questions…?

If you have made it this far then I should have answered most questions, at least the ones that can be answered at this time. If you think of something that I have missed, feel free to post or send me a message on  Facebook.