Winter weather possible for the Western Carolinas on Friday, many questions remain...

Good Wednesday afternoon…we are nearing the end of the first week of Meteorological Winter and its no rest for the weary forecaster…

 

We are still monitoring for the potential of some light wintry precipitation that could impact our coverage area on Friday and Friday night. Computer models today still provide a lot of uncertainty in the forecast on Friday but the one thing we do have some confidence on is the frontal boundary that brought up some rain last night will remain somewhat active across the Southeast.

 

Pieces of upper level energy along with weak surface lows along that boundary will keep the region on the wet and unsettled side through the early part of the weekend. Meanwhile cold air to our northwest continues to slowly creep into the region. Due to the shallow nature of this first surge of arctic air, the Appalachians is doing an adequate job in blocking the low level cold from invading those east of the mountains, however aloft the cold air is doing a better job at moving in…and that all leads us to the forecast quandary for Friday.

 

Can the low level cold air seep in before or during the next round of precipitation? That’s the million dollar question at this point…

 

By early Friday morning moisture will begin to approach the region from the southwest with temperatures at or just above the freezing mark at the surface, however just a few thousand feet above the surface temperatures are below the freezing mark. This moisture will continue to stream in as weak low pressure develops along the Gulf of Mexico. Precipitation will be at its climax during the afternoon hours of Friday with a tapering off of rates expected by Friday night.

 

The maps provided below are from the GFS model from the afternoon run, this model in particular is the warmest in regards to surface temperatures as it keeps temps steady in the 35-37 degree range through the entire timeframe in question. Other models including the NAM and European are just a tad colder but still at or just above the freezing mark.


 GFS Precip (Friday 7 am)

GFS Precip (Friday 7 am)

 GFS Precip (Friday 1 pm)

GFS Precip (Friday 1 pm)

 GFS Temperatures (Friday 1 pm)

GFS Temperatures (Friday 1 pm)

 GFS Precip (Friday 7 pm)

GFS Precip (Friday 7 pm)


So…at this time our forecast is leaning toward a mix of rain and some snow beginning on Friday morning and remaining that way through most of the day. Toward evening as some cold air filters in we could see a changeover to all snow before ending Friday night. This is a result of the marginal boundary layer temps and with the questions remaining in regards to the amount of moisture available. No snowfall accumulations are expected at this time.

The depth of moisture as just as important as the cold air due to the process of crystal growth aloft needed to produce snowflakes capable of reaching the surface.

 

Precipitation amounts at this time look to be heaviest in our southern and eastern tier with amounts lighter along the Blue Ridge through Friday evening.

 

 

With this event upon us, we are dusting off the Winter Storm Index and using it  for the first time this winter season and placing it at level 1 (Social Media Talk) at this time. Plus we have a storm overview showing a lot of the certainties and uncetainties to the forecast at this time...


Winter Storm Index 12-6-17.png
Winter Overview 12-6-17.png


Our next full update on the Friday rain/snow potential will be posted tomorrow...