Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 011452

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

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.


As of 947 am EST: Radar shows the most robust convective band
weakening and moving off to the east, leaving behind a large area of
light rain across the Piedmont. Meanwhile, the wide band of precip
associated more directly with the front itself was also showing
a weakening trend. Coverage of light rain overall was shrinking,
as suggested by some of the guidance. This may play into another
update around midday, but for the time being we are content to
keep carrying a chance of rain well into the afternoon. Temps have
probably already reached highs for the day with the rain-cooled
air in place now and the cooler air moving in with the front later
in the day.

Otherwise, gusty northwest winds will also develop in the cold
advection through the day, but with gust values remaining below
advisory criteria in the windiest mountain locations where a
secondary, reinforcing cold fropa arrives this afternooon. 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. 1031 mb surface high pressure will then
build over the OH River valley tonight, with chilly thicknesses
spilling southward east of the Appalachians.


As of 145 AM EST Monday...A split flow pattern aloft will evolve
into a general trof over the period as a srn stream h5 low traverses
the FA Tue night into Wed. A broad offshore sfc low will be
supported by this upper energy and will bring a decent amt of
GOM/Atl moisture to the area beginning Tue afternoon. Meanwhile, a cP
sfc high will track off the midAtl coast and provide a weak insitu
ridge before breaking down Wed morning.

This general pattern will likely support a wintry mix of precip
across the NC mtns Tue night, with light snow transitioning to
freezing rain, then to rain by 15z Wed. The latest NAM soundings
dropped across the NC escarpment show a strong and deep warm nose
interacting with sub-freezing sfc temps abv 3.5 Kft to support
-fzra, while the GFS is notably warmer with llvl partial thicknesses
and indicates more of a sn/ip situation. So, have blended the llvl
thermal profiles and used a top down approach for p/types, which
generated arnd an inch of snow across the higher peaks with perhaps
up to 2 inches over the Smokies. The freezing rain would begin arnd
08z and persist into mid morning with a few hundredths of an inch
favoring the nrn BR escarpment. If these ice amts hold over the next
few fcst cycles, an advisory may be issued. The atmos dries out
during the day Wed as a Canadian high drops south and reinforces a
srn stream sfc high building in from the west thru the period. Max
temps will remain a little below normal each day, while mins hover
arnd or a bit abv normal levels.


As of 210 AM EST Monday...The ext range fcst looks to remain quite
dry as the models continue to show a suppressed large-scale pattern
over the SE CONUS. Thus, little change was made to the already dry
fcst. A stg subs zone will slowly cross the area, while a couple cP
sfc highs build south and force a favored storm track well south of
the FA each day. With winds generally maintained n/ly and weak CAA
flow in place beginning Thu night, expect max temps to begin the
period Thu abv normal, then cool a little below normal Fri thru Sun.
Dewpoints will drop and mix out each afternoon, which could create
some fire-wx concerns across NE GA based on RH each afternoon,
except Sun when llvl moisture begins to return to the area. Winds
shud remain relatively weak, however, and plenty of sunshine will be
had making for rather nice days for early March.


At KCLT and elsewhere: The heaviest showers have aligned
along the leading edge outflow of pre-frontal moisture, and this
will be accompanied by briefly gusty northwest winds. Precipitation
will become lighter throughout by late morning, and winds may toggle
briefly back toward the southwest at all but KAVL ahead of a
trailing, reinforcing cold front arriving this afternoon. During the
best precip coverage this morning, anticipate mainly lower end VFR
cigs with tempo MVFR at times. Visibility may go briefly IFR during
the best downpours throughout. Expect a return to gusty northwest
flow for the afternoon hours, with cigs generally returning to lower
end VFR before gradually lifting and scattering by evening.
Anticipate mainly just scattered high clouds tonight as drier high
pressure builds in from the north. Most locations lose the gusts by
early evening, but KAVL will be the exception with continued NW
gusts into the 20s well into the nighttime hours. Surface winds will
toggle more northeasterly at KCLT early Tuesday.

Outlook: VFR conditions briefly persist into Tuesday under dry high
pressure. However, moisture may surge back into the area by Tuesday
night, 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...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High  98%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High  98%     High 100%     High 100%
KAND       High 100%     High 100%     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:




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