Image: NOAA
December 21, 2020
❄ Odds for a White Christmas are rising for the Ohio Valley, Appalachia, and parts of the interior Mid-Atlantic...
From a historical perspective, the odds of a White Christmas for the Ohio Valley, and lower elevations in the Appalachian Mountain Chain are less than 25%. In the northern Ohio Valley a 1 in 4, or 1 in 5 chance dwindles to a 1 in 10 chance farther south. When you reach the far southern Ohio Valley into the northern Tennessee Valley it shrinks farther to 1 in 20. This year, the risk of seeing a White Christmas is on the rise thanks to a storm system organizing, deepening, and delivering cold air at the right time.

A strengthening cold front will push into the region late Wednesday into early Thursday morning. Out ahead of it, southerly flow will lead to many areas reaching the upper 40s to upper 50s for highs. This will likely catch people off guard with well-above normal temperatures, but it is that tenperature gradient that will allow a southern wave to develop in the vicinity of Atlanta, Georgia, late on Wednesday. That low will rapidly deepen and freight train cold into the Ohio Valley and Appalachia during Christmas Eve, Thursday.

Image: NAM/Pivotal
December 21, 2020
As the low continues to feed on the warm, moist flow in the warm sector against the cold, dense air behind it, heavy precipitation will break out. Intense thunderstorms, and heavy rainfall can be expected, where places just last week cashed in on a heavy snowfall as highs soar into the 60s. Behind the front, heavy snow squalls and temperatures plummeting into the teens and twenties will set the stage for accumulating snow, leading to a solid chance of areas in the Ohio Valley and Appalachia receiving a White Christmas. Specifics are still 48-60 hours out, due to the nature of this storm being in its formative stages. Bottom line, though, is this secondary wave will become a high impact storm for Christmas Eve and Christmas Day.

☃️ Forecast Provided By: Joshua Ketchen

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