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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 010601
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
101 AM EST Mon Mar 1 2021

.SYNOPSIS...
-- Changed Discussion --
A cold front will cross the mountains early this morning and then
cross the foothills and Piedmont through the late morning and early
afternoon hours. Dry high pressure will build over from the north
tonight 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.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 1245 am EST: The latest surface analysis reveals a cold front
positioned roughly from Knoxville to Chattanooga TN early this
morning and making slow progress eastward toward the NC mountains.
Ahead of this boundary, gusty southwest winds have developed over
the higher terrain, but with max gusts likely staying just below
advisory values of 45 mph along the highest ridge tops.
Precipitation will begin to fill in quickly across the NC mountains
as the frontal zone and associated H5 vorticity reach the spine of
the southern Appalachians circa 09Z, march on to the Blue Ridge
Mountains eastern escarpment by 11Z, then move east across the
foothills/Piedmont through late morning. The PoP trends will follow
this pattern, with categorical coverage likely at some point for
most locations, but with QPF values much better along the TN border
areas early this morning, and particularly across Graham and Swain
Counties in the best upslope flow and longest dwelling period of the
heavy rainfall. With QPF values around 1.5+ inches in these areas,
minor hydro problems could arise, but this should not be sufficient
for any widespread flooding and a Flash Flood Watch does not appear
to be needed. Instability remains quite marginal in profiles. Will
generally keep thunder out of the forecast, but an isolated rumble
cannot be completely ruled out with the fropa.

Temperature trends will be hard to pin down today, with falling
temps likely in the cold advection across the mountains, steady
temperatures across the northern tier in balanced cold advection but
warming post-fropa downslope flow, and a modest afternoon bump in
temps in the western Upstate and NE GA. Gusty northwest winds will
also develop in the cold advection through the day, but with gust
values again below advisory criteria in the windiest mountain
locations where a secondary, reinforcing cold fropa arrives this
afternooon. A trailing but vigorous shortwave will reach the
mountains again by late day. However, the deeper moisture should
settle generally southeast of our Piedmont counties by sundown along
with the passing cold front. Any shallow upslope moisture into the
western mountains will dry up fairly quickly in the cold air along
the spine of the mountains this evening. So, any isolated snow
showers or flurries will be short-lived and non-accumulating.
1032 mb surface high pressure will then build over the OH River
valley tonight, with chilly thicknesses spilling southward east of
the Appalachians.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY 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 /06Z MONDAY THROUGH FRIDAY/...
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At KCLT and elsewhere: Anticipate mainly thickening and lowering VFR
ceilings early this morning as a cold front and associated deeper
moisture moves in from the west. The narrow band of frontal moisture
should provide MVFR to lower end VFR cigs during the passsage of the
main bands of rain showers with the front, generally from just
before daybreak west to mid-morning east. VFR cigs will then lift
and scatter through the afternoon hours, with just FEW to SCT high
clouds tonight as drier high pressure builds in from the north.
Gusty southwest flow this morning will become slightly gustier W to
NW flow this afternoon following fropa and the onset of cold
advection. Most locations lose the gusts by early evening, but KAVL
will be the exception with continued NW gusts into the 20s through
06Z Tuesday.

Outlook: VFR conditions briefly persist into Tuesday under dry high
pressure. However, moisture may surge back into the area by Tuesday,
with restrictions and precipitation chances returning through early
Wednesday. Another round of drying is expected by late Wednesday,
likely continuing through the end of the work week.

Confidence Table...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       High 100%     High  95%     High 100%     High 100%
KGSP       High  95%     High  93%     High 100%     High 100%
KAVL       High  85%     High  96%     High  99%     High 100%
KHKY       High  99%     High 100%     High 100%     High 100%
KGMU       High  95%     High  96%     High 100%     High 100%
KAND       High  97%     High  94%     High 100%     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
-- End Changed Discussion --

&&

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

&&

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