• Chief Meteorologist Chris

HIGH IMPACT WEATHER BRIEFING; PREPARATIONS FOR WINTER STORM BEGIN

Good Tuesday Morning. Apologies for this coming out about 2 hours late. Overnight models continue to indicate the cold air will in deed make it in the area ahead of the storm system, boosting confidence that a major winter storm is in the making for the weekend.


Over the last 24 hours since the last briefing confidence has went up that Western North Carolina, Northwest Piedmont of North Carolina, and Upstate SC could be looking at a significant early season winter storm.


Synopsis:

Low pressure will move from the US West Coast to Eastern Texas by Saturday Morning. A cold front will pass through the region Friday Night, allowing for cold high pressure to build in from the Northwest. Saturday afternoon moisture will stream out ahead of the approaching low pressure system and by Saturday Evening it will be overrunning the cold high pressure. Initial precipitation types could be sleet and freezing rain, especially in Upstate South Carolina and the Southern Foothills (Rutherford, Polk, Cleveland). As moisture falls into the cold drier air, through a process called evaporative cooling, the atmosphere will cool bringing the entire column of air below freezing. This should allow for the majority of the area to quickly change over to snow Saturday Night. Travel could quickly become hazardous due to a layer of ice under the snow, especially on elevated surfaces. Additionally the ground should be able to efficiently cool due to evaporative cooling that will cause accumulations to begin pretty quick.


Through the night on Saturday periods of heavy precipitation will fall. Currently profiles suggest that this would be primarily snow across the entire coverage area. Sunday Morning the low pressure should be between Tallahassee Florida and Macon Georgia. This will increase precipitation rates across the area. At the same time a warm nose of air will move in aloft between 5,000 and 8,000 feet above ground level. The models are still having a hard time depicting just how far North this warm nose will make it. The GFS is more bullish with the warm nose than the EURO. Where the warm nose moves in aloft it is likely that the surface layer will remain below freezing. This would indicate a freezing rain scenario where that warm nose does move in. So the ongoing forecast will continue to indicate a winter mix of sleet, freezing rain, and snow on Sunday. Temperatures look to be in the upper 20's through the day Sunday. A couple of areas along the NC/SC line could bump up into the low 30's Sunday Afternoon but I question that a bit as heavy precipitation will be falling into the dry air, effectively keeping it subfreezing. Precipitation looks like it could continue into the nighttime hours Sunday Night. It is likely that the entire viewing area will continue to see this as the frozen precipitation variety. It is still too soon though to know exactly so for now will leave the chance of a cold rain Sunday Evening into the overnight period. Again, that liquid rain scenario is looking less and less likely.


From there the situation becomes even more interesting. By Sunday Night low pressure will move off the coast but models now indicate the upper low will hang back and deepen over the area. If this upper low does close off and meander over the area then that could prolong precipitation well into Monday, if not Tuesday. Too much uncertainty remains in this portion of the forecast for any kind of certainty. If this does occur temps could stay in the 30's with precipitation, probably snow at this point because of the cold air associated with the upper low, falling right into Monday Night. These upper lows are a weatherman's woe because they are so tough to forecast just a day out, much less 6 or 7. For winter lovers though this is exciting!!!!


Timing:

Saturday night through Sunday Night, possibly extending into Monday or Tuesday.


Potential Impacts:

Impacts to power, emergency response plans, travel, cell phone coverage, and phone service could occur.


Chris White

Chief Meteorologist




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