Discussion from GSP
In my opinion bullish for them 7 days out.
Toward the end of the period, interest certainly piques as all
global models are depicting a deep upper
trough digging out of
Canada into the Plains mid-week, pushing east toward the
Appalachians on Christmas Eve. For this far out, consensus in the
anomalously amplified and cold synoptic pattern is pretty strong,
and though the
GFS is a bit faster with the potent
front, timing
differences are remarkably low. Give or take a few hours, the
front
looks to be pushing into the Appalachians sometime early on
Christmas Eve, with deep
moisture fetch off the Gulf bringing
potentially efficient
rainfall to the region, especially in the SW
mountains. This deep
moisture pushes east fairly quickly, though
lapse rates and attendant
moisture under the upper low with the
secondary shot of
vorticity may be enough for some lingering precip
on Christmas morning. As mentioned above, this system is anomalously
cold, with most of the 12z guidance coming in not bringing even the
Piedmont out of the 30s on Christmas Day. The official forecast is
warmer than that, relying heavily on blends, but wouldn`t be a bit
surprised to see forecasts trending colder in the next few days. As
for the
moisture, new operational runs are drier for Christmas day,
but again leaned toward the blend and so do have low-end
pops into
the end of the forecast. Conditionally speaking, if precip occurs,
with the very cold temperatures, it`ll either be rain or snow, so
technically the official forecast will carry
slight chance snow
showers early Christmas morning with rapid drying after daybreak.
But residents across the Piedmont of the western Carolinas and
northeast Georgia are cautioned not to get excited as this is still
7 days out and we`re only talking 20%
pops or less. In the
mountains, however, this is a slightly different story, where even
WPC`s winter
outlook does have low-end chances of accumulations.