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000
FXUS62 KGSP 281934
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
234 PM EST Sun Feb 28 2021

.SYNOPSIS...
A cold front will cross Tennessee tonight then cross our
area by mid day Monday.  Dry high pressure will build over from the
north as the high center moves from the Great Lakes to the Mid-
Atlantic coast Monday night into Tuesday. Unsettled weather returns
from the west Tuesday night into Wednesday morning. Another low
pressure system may affect the Gulf Coast region Friday into
Saturday.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 205 pm: Warm sector air mass is now firmly in place across the
forecast area, with gusty SW winds and increasing insolation having
allowed for a rapid warm-up...by as much as 15 degrees in just a
couple of hours...after the cool start beneath earlier fog/low
stratus. Spotty shower activity is noted across the great valley of
East TN, and some of this will probably develop into SW into the
evening on the strength of mechanical lift. May also still see some
showers pop in the lower/eastern SC Piedmont, where weak sbCAPE is
developing.

Otherwise, potent short wave trough/upper low will dig from the
Canadian prairie this afternoon to the northeast Conus by the end of
the period, allowing a fairly strong frontal zone to move across the
TN and OH Valleys late this afternoon into the evening. A frontal
band of convection is forecast to fill in across this region during
the evening, as the front encounters moderate instability. In fact,
the frontal band should be quite vigorous as it approaches the
southern Appalachians late tonight, and the NC mountains are where
the highest rainfall totals are expected across our forecast area
through the period, with 1-2 inches appearing likely across the
Smokies and vicinity. However, with meager-at-best instability
expected across our area and lackluster upper air support, to go
along with the typical high terrain disruption of the frontal
circulation/low level convergence, the intensity and coverage of the
frontal band is forecast to diminish as it moves across the forecast
area Monday morning. As such, the threat of severe convection should
remain west of the area, while any low end excessive rainfall threat
will remain confined to extreme southwest NC. Despite the expected
diminishing trend in the frontal band, it should hold together long
enough to support categorical pops across the entire area during the
morning. Precip should be all but done by mid-Monday afternoon.

Other than a brief period this evening, gusty SW winds are expected
across much of the area into Monday morning, before gusty NW winds
develop behind the front late morning into the afternoon. Min temps
will be very warm tonight, and daily record warm lows...which are
generally around 60 at the main climate sites...will be in jeopardy.
After the very warm start Monday, developing cold advection will
limit the diurnal heating potential, and only modest warming is
expected across the mtn valleys and Piedmont/foothills, while temps
will slowly fall throughout the day across the high elevations.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 1205 pm EST Sunday: As sfc ridging rolls over into the region
Monday night, the llvls will continue to dry, but model cross
sections depict varying degrees of mid and upper level moisture
lingering within the west to wsw flow aloft.  Gridded model sky
cover solutions are all over the place, and at this point, the
generic partly cloudy should cover it.  Downstream of developing
southern stream low pressure, clouds should thicken again as Tuesday
wears on and within the cool NE llvl flow, maximum temperatures will
be back to below climo values.

From late day Tuesday into Wednesday morning, as forcing and better
moisture associated with the encroaching southern stream system
overspreads the region, pcpn will be become widespread.
Vertical temperature/moisture fcst profiles over the NC mtns
still suggest that a period of snow developing into a wintry mix
remains possible during this time.

Fast moving s/wv passage is expected on Wednesday, the axis of which
is timed to be near the coast by the afternoon.  Whatever the
orientation and cvrg of pcpn shield is in the morning should be
replaced by dry slotting by Wed afternoon.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 1215 pm EST Sunday: No change to the going dry and mild fcst
for Thursday as extended range guidance remains in good agreement in
progging deep layered dry air within the cyclonic flow aloft and a
dry northerly llvl flow.  Within the lingering llvl northerly flow,
a dry cold front is progged drop south through the region on Friday
ushering in another period of below climo temperatures.

The mean pattern does not change very much for next weekend,
featuring a lingering eastern CONUS trough.  Forcing rounding the
base of upper trough is progged to activate baroclinic zone, but way
off to our south and into the offshore Atlantic on Saturday into
Sunday.  The dry conditions will continue with temperatures around 5
deg F below the early March climo each day.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Lingering low cloud cover is scattering/
clearing early this afternoon and visby is (finally) improving
quickly in the KCLT area. VFR conditions should be seen at all sites
no later than 20Z. Most terminals will see gusty S/SW winds this
afternoon that will likely diminish a bit this evening. However, SW
winds should begin to pick up again after midnight as surface
gradient increases in advance of an approaching cold front. Can`t
rule out a brief return of fog btw roughly 03-06Z. However, fog
chances will decrease once winds pick up late tonight. Cigs should
lower to MVFR after midnight as rain chances also increase. Most
sites will see categorical SHRA for several hours from around
daybreak through the morning. Improving conditions are expected at
KCLT during the 18Z-00Z Monday outlook period, with NW winds
developing in the wake of the front.

Outlook: Drier high pressure building back into the area late Monday
will result in improving flt conditions through early Tuesday.
Moisture will then surge back into the area by the end of the day
Tuesday, with restrictions and precipitation chances returning Tue
night into early Wed. Another round of drying is expected by late
Wed, likely continuing through the end of the work week.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High  98%     High 100%     High  90%     High  96%
KGSP       High  89%     High 100%     High  96%     High  92%
KAVL       High 100%     High  96%     High  83%     High  92%
KHKY       High  92%     High  95%     Med   68%     High  92%
KGMU       High  92%     High  99%     High  97%     High  91%
KAND       High  93%     High 100%     High  94%     High  91%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...HG
NEAR TERM...JDL
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...JDL