602 
FXUS62 KGSP 080502
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
102 AM EDT Fri Oct 8 2021

.SYNOPSIS...
An upper level low pressure over the mid Mississippi Valley will 
focus a very moist southerly flow off the Gulf of Mexico into our 
region through tonight before it moves toward the Great Lakes. 
Expect periods of widespread showers and locally heavy rainfall 
through Friday, especially for the mountains and foothills. As this 
low and its associated front moves east of our area this weekend, 
dry high pressure will be in place into early next week. Summer-like 
temperatures are likely next week along with dry high pressure.

&&

.NEAR TERM /THROUGH TODAY/...
As of 1am EDT Friday: Showers are fairly light at this time, though 
more showers could pop-up overnight, especially over the mountains, 
as moisture levels remain high, and presence of a trough west of the 
region will continue to provide decent forcing.  CAPE levels are 
minimal, and thunder is unlikely prior to late Friday morning.  Hi-
res models suggest next round of heavier rain will move in from 
Georgia after 7am.

Additional rounds of 1"/hr rain rates could lead to flash flooding 
in areas that received a lot of rainfall today.

Otherwise...there is good agreement on a negatively tilted trough
pivoting NEWD thru the area late tonight into Friday. This should
provide some support for convection. Meanwhile, an easterly 10-15 kt
fetch off the Atlantic is sustaining PWATs of 1.5" or higher. There
will also continue to be some elevated CAPE of 500 J/kg and an
axis of low-level convergence between easterly flow associated
with weak circulation off the Carolina coast and southerly flow
associated with the lifting upper low over the Mid-South. So with
all those ingredients in place, the FFA was expanded by the day
shift to include the rest of the NE GA Piedmont and the Upstate
west of the Saluda River, and was extended in time until noon
Friday, given the disagreement among the guidance on the timing
of the heavy rain. Rainfall totals may be highly localized, with
some areas getting 1-3" possible. Lows will be well above normal
under cloudy skies and patchy fog.

With the models trending later with the passage of the upper trough,
have bumped up PoPs for Friday, especially across the NC foothills
and Piedmont. Hopefully, whatever axis of deepest moisture and
convergence will shift east of the FFA area. Some breaks in the
clouds possible, but overall will stay cloudy and temps will be
slightly below normal, and will continue to feel muggy.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
As of 100 PM Thursday: The closed low that has that has helped
blast the area with lots of rainfall will slowly evolve into an
open wave and lift towards the Midwest and Upper Great Lakes region
during the beginning portions of the forecast period. The upper
trough axis in response will push into the region Friday night
into Saturday. Broad high pressure over New England and Atlantic
Canada will keep the CFWA in an in-situ CAD through the first
part of the short-term. With the CAD in place and an easterly
fetch from a tropical disturbance just off the NC Coast, expect
showers to linger into the overnight hours Friday, mainly in the
eastern portions of the CFWA. The upper trough will begin to lift
to the north and east during the day Saturday and ridging to the
west will begin pushing into the area and should allow for drier
conditions for Sunday. Temperatures will be at or slightly above
normal for highs, while low temperatures remain well above normal.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 130 PM Thursday: Deep upper ridging will gradually propagate
over the East Coast from the west throughout the period and
will be the main influence on the overall forecast. Dry and
very unseasonably warm conditions will be the result from this
setup with the ridge expected to linger over the area through day
7. Model guidance begin to diverge as the GFS begins to breakdown
the ridge in response to a shortwave trough to the west with an
attendant cold front. The cold front is not expected to reach the
CFWA during the 7 day span, so I don't know why I'm wasting your
time with it. The ECMWF has the same synoptic pattern, but is a
day or so slower in the cold front's progression compared to the
GFS. Otherwise, summer-like conditions will be the main weather
headline for much of next week with highs and lows ~5-10 degrees
above normal each day and night.

&&

.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Looks like at least another 24 hours in
the soup as the pattern remains unchanged with copious low level
moisture moving upslope on a S/SE flow. Two low cloud decks had
already developed at this hour, one at the MVFR level mainly over
the NC Piedmont and foothills, and one at the IFR level mainly
over Upstate SC. All TAFs will begin with MVFR/IFR restrictions,
with the fcst deteriorating to IFR/LIFR by/during the early morning
hours as in previous nights. Wind will stay light NE. Precip could
develop at any time, mainly closer and over the mtns. Friday will
play out similarly, with another round of rain likely through the
morning hours, then improvement to MVFR in the afternoon. Enough
holes may open to allow enough heating for some thunderstorm
activity toward the end of the TAF period. Wind will remain NE.

Outlook: Finally, some drier air will try to work in from the west
over the weekend. Conditions will return to prevailing VFR beginning
on Saturday morning. Low-level moisture may linger, keeping a
chance of low cigs and fog, especially late night/early mornings.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch until noon EDT today for GAZ010-017-018-026-
     028-029.
NC...Flash Flood Watch until noon EDT today for NCZ033-049-050-052-
     053-059-062>065-501>510.
SC...Flash Flood Watch until noon EDT today for SCZ001>005-010-011-
     019.

&&

$$
SYNOPSIS...CAC
NEAR TERM...ARK/PM/WJM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...PM