Winter Weather threat for Foothills is lowering, some light snow still possible through Monday evening

Good Sunday morning…computer model data overnight has come into better agreement on a storm system that we are monitoring to impact the region. A weak surface low will pass by the region today bringing a cold, cloudy and at times wet Sunday to the region. Behind the initial surge of moisture an upper level trough will dive from the Plains toward the Tennessee Valley today. That upper low will ultimately close off and help produce additional moisture by tonight through the first half of Monday… this time with colder air aloft to work with.

 

Model trends over the past couple days indicated the potential for wintry precipitation for the mountains and even east of the Southern Appalachians during the early Monday time frame as that upper low is scheduled to pass through. Model solutions were showing varying outcomes as they each had different tracks of the upper level dynamics…fortunately overnight those models are converging toward one solution of the upper low going directly over the Western Carolinas in a neutral tilt fashion and then doing slightly negative tilt just east of the Appalachians.

 

As you can see the short range NAM and global GFS are pretty close to each other now in terms to positioning and track within 24 hours of the event…


 

 

 GFS 850 mb heights (8 pm tonight)

GFS 850 mb heights (8 pm tonight)

 GFS 850 mb heights (2 pm Monday)

GFS 850 mb heights (2 pm Monday)

 

The end result in all of this is a lowering of the winter weather potential east of the Blue Ridge as the low track will keep the coldest air and best moisture/lift just north and west of the Foothills. As is common with winter upper level low pressure systems the best chance for snowfall lies on the north and northwest quadrant of the low. With the low track now being indicated, the better chances of snow now look to be right along the NC/VA state line and into Southern Virginia.

 

 

With this development in the guidance we have adjusted the precip forecast map to better fit the low track and temperature placement. The southern half of the county coverage area will now likely see little to no wintry precip as temperatures by Monday morning will remain in the mid to upper 30’s.

 

Once you get to interstate 40 (in the blue shading) the surface temperature will be slightly cooler but the low track is not favorable for a quick band of snow to develop prior to its ending. We are not going to completely write out a quick changeover at the end but the threat is realistically lowering with each passing hour.

 

 And then in the purple shading right along the Blue Ridge the first half of this event will gradually end on Monday and for those communities, northwest flow on the back side of the upper low will help promote snow shower activity in the mountains lasting through Monday night…and of course with any usual northwest flow event a few of those snow showers could break containment. Places like Globe, Jonas Ridge, Ashford, Little Switzerland could see a snow shower quickly deliver a light coating on grassy areas.

 

Snowfall Forecast 5 am 3-11-18.png

 

 

 

We will continue to monitor local guidance through the rest of the day along with radar trends once we get into tonight…but our confidence on this forecast is starting to increase that impacts will be low in the Foothills, the worst being in northwest sections of Burke, Caldwell and McDowell Counties…

 

 

Additional briefings will be posted on this event later today along with general forecast discussion.

 

 

Daniel Crawley

Foothills Weather Network