GSP
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 215 PM EST Tuesday: The forecast has trended a touch colder
for the period of interest Thursday into Thursday night. The setup
looks good for cool and dry air to spill into the region behind the
frontal boundary settling just south of the area Wednesday night.
The operational models and the associated SREF/GEFS plumes now all
bring accumulating snow potential down to the I-85 corridor, from
GSP to CLT. There are several wrinkles in the forecast, however. The
NAM profiles exhibit a bit more of a warm nose later Thursday as
profiles wet bulb down in the returning upglide moisture over the
frontal zone. The warm nose appears transient on the NAM profiles,
and is less prominent for all but the extreme southern tier on the
other models and blends. Thus, the thinking is that although brief
mixed ptypes are possible at times, the forecast will be
predominantly a rain/snow line issue. The deepest forcing and
moisture should cross the region Thursday afternoon as upper
divergence ramps up and a positively-tilted shortwave dives
southeast from the upper Midwest into the central/southern
Appalachians. Meanwhile, surface low pressure along the frontal
boundary will deepen along the coastal waters and a window of decent
frontogenesis will set up over the central and eastern Carolinas
into Thursday evening. The back edge of this frontogenetic axis
could flirt with our I-77 Piedmont Counties - something to watch out
for as it would mean better precipitation rates.
All told, the best 2 to 3 inch snow accumulations for this
relatively short duration event should affect the higher ridges of
the NC mountains, with lighter accumulations east of the mountains
and mainly northwest of I-85, but with a dusting southeast of the
Interstate. Some wintry weather potential will be featured for most
zones in the HWO this afternoon, but no Watches will be posted at
present.
Drying should occur rapidly behind the passing wave Thursday night,
unless any lingering bands of precipitation west of the coastal low
persist east of I-77. Dry ridging will set up over the southeast on
Friday with continued cool temperatures.
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