Tracking two chances for Wintry Weather

Posted at 6:26 PM, Nov 21, 2013

RICHMOND, Va. (WTVR) – An arctic air mass is still on schedule to invade the region this weekend, and depending on the evolution and speed of a southern stream storm system, a couple of brief bouts of wintry weather might also be in the cards.

I’ll start with the cold air…it’s coming, no doubt about it, and it will be by far the coldest air we have seen so far this season.  The leading edge of the cold air will move into the area early Saturday.  We’ll only see modest cooling at first, but the cold air will rapidly overspread the area Saturday night into Sunday.  Below shows the arrival of the initial wind shift, but not necessarily the coldest air.Zach 3 day RPMfront

The three images below show the progression of the arctic air Saturday and Sunday, as it moves southeastward into the Mid-Atlantic.

N Amer 500mb6aN Amer 500mb6p N Amer 500mbSun6a

The potential for wintry weather is much less certain, being tied to a very slow-moving moving upper-level system currently in the developing stage off the coast of California.  This system will be cut off from the main storm track, making its movement eastward across the country very difficult to accurately time.  Below is a snapshot of this system midday Sunday over the 4-corners region, based on the most recent Euro model run.

500 Euro Low

The two most reliable medium range operational models continue to bring the rainfall associated with this system into Virginia at different times.  For the purpose of this blog post, I’ll focus on the Euro model, which portrays two brief windows for wintry weather in our area.

The first chance will come Tuesday morning.  If the Euro ends of being correct with the faster storm motion, rain would overspread cold and dry air at the surface in western and much of central Virginia, bringing us a 2-3 hour period of freezing rain.  Temps will quickly rise by mid-morning, with just rain for the remainder of the day.

The second chance will come as the storm system exits the area to the northeast.  Precipitation indicated by models usually ends a little prior to when the model says it will, but even so, there could be a little moisture left when another cold blast arrives to bring us a brief changeover to sleet or snow flurries.

Neither event will be very big, but in Virginia, a little goes a long way when considering wintry weather and its effects on the populace, especially if it’s ice.  There is no way of knowing which model is handling the future track of the southern system best, so at this point, I’ll continue to watch it from all angles and update you with any changes/trends I see when I see them.  -Zach

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