National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 010237
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
937 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 935 PM: Low level moisture, and the resulting lower clouds,
remain limited mainly across the mountains this evening, with mainly
high clouds elsewhere. Without the low level moisture, the
mechanical lift hasn`t resulted in any appreciable precip.
Convection closer to the frontal zone also remains well to our west
and north. While an isolated shower is possible across the mountains
until midnight, the bulk of the showers should remain to our west
until well after midnight. The forecast is on track with only minor
changes for current conditions.

Otherwise, potent short wave trough/upper low will dig from the
Canadian prairie to the northeast Conus by the end of the period,
allowing a fairly strong frontal zone to move across the TN and OH
Valleys into the evening. A frontal band of convection will 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.

Winds diminish this evening before gusty SW winds redevelop across
much of the area overnight into Monday morning. 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. This
will likely negate any potential record warm lows as low temps for
the day occur near midnight Monday night.

&&

.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 asscoiated 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 /03Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: BKN stratocu across the mountains and SCT cu
BKN cirrus will continue through the evening. Cigs lower to MVFR
overnight ahead of the approaching cold front. Showers will move in
with the lower cigs and move east by noon. Vsby restrictions are
possible in the heavier showers, but timing too uncertain to include
for now. Can`t rule out a rumble of thunder but prolonged TS looks
unlikely given the lack of instability. Cigs return to low VFR by
noon with those clouds scattering out during the afternoon. SW wind
continues through the evening ahead of the cold front, SSW at KAVL.
Gusts pick back up ahead of the front as well. Winds shift to NW
behind the front and remain gusty. Winds briefly drop off some,
possibly turning more westerly, early in the afternoon, then return
to the NW becoming gusty once again.

Outlook: VFR conditions expected Monday night and early Tuesday as
dry high pressure briefly builds in. 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...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High 100%     High  91%     High  90%     High 100%
KGSP       High 100%     High  93%     High 100%     High 100%
KAVL       High  97%     High  86%     High 100%     High 100%
KHKY       High 100%     High  93%     High 100%     High 100%
KGMU       High 100%     High  94%     High 100%     High 100%
KAND       High 100%     High  94%     High  98%     High 100%

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/RWH
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...RWH