233
FXUS62 KGSP 090824
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
324 AM EST Sat Nov 9 2024

.SYNOPSIS...
Dry high pressure builds in from the north today before a strong
cold front brings rain chances back to the area Sunday into Monday.
High temperatures will be much cooler this the weekend, with
afternoon temperatures on Sunday expected to fall below normal,
before highs trend back to above normal values early next week. Dry
high pressure returns Tuesday into Wednesday before another cold
front increases rain chances again on Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 310 AM Sat: Northerly flow observed over most of the CWA as
high pressure builds in from the Great Lakes, behind a backdoor
cold front, and dewpoints have begun to tumble as a result across
the northern half of the CWA. This drying trend will generally
continue toward the SW, although dewpoint depressions remain small
over the lower Upstate and GA zones. Slight mixing has developed
which has led to some improvement even in the more humid areas,
but some isolated areas of dense fog may linger thru daybreak in
the Lakelands.

The sfc high will build south and east toward the Mid-Atlantic coast
by the end of the day today, supported by a moderately strong upper
ridge. Morning stratocu near the front in our southern zones are
likely to persist in some fashion thru the day and perhaps also
developing and near the Escarpment along/west of I-26, as a result
of either convergence in easterly flow or warm upglide. Higher
clouds will also filter in, emanating from the midlatitude cyclone
on the other side of the ridge axis. Not seeing enough moisture
during the day to support mentionable PoPs; accordingly we do not
expect CAD to affect high temperature potential. Temps will be
cooler simply given the freshly arrived, dry continental airmass;
the Piedmont and lower elevations will see highs in the upper 60s
to near 70, still a few degrees above normal.

The warm upglide will moisten tonight and stratus or stratocu
will thicken over the western part of the area, but chance of PoP
still will be confined to the mountains, given proximity to front
and where moisture will be best aloft; even then chance is below
30%. Mins will be notably cooler as well, but still a few degrees
above normal with cloud cover, and with hybrid CAD still not
looking particularly likely to develop given low chance of precip.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
As of 130 AM EST Saturday...

Key Messages:

1) Cold Air Damming will Allow for Below Normal Highs on Sunday

2) A Cold Front Brings Rain Sunday into Monday

3) Above Normal Highs Return Monday as Cold Air Damming Erodes

Cold air damming will be in place Sunday ahead of an advancing cold
front leading to mostly cloudy skies and increasing rain chances
through the day. As a result, highs on Sunday will end up a few
degrees below normal. Lows Sunday night will end up ~15 degrees
above climo thanks to cloud cover and rain limiting radiational
cooling. The front will sweep across the forecast area on Monday,
keeping rain chances around and gradually scouring out cold air
damming. How quickly the cold air damming erodes on Monday will be
the main question. If it erodes prior to peak heating a rumble of
thunder cannot be entirely ruled out. However, removed thunder
chances for now as cold air damming usually erodes slower than what
the global model guidance shows. Highs on Monday should rebound to
~10 degrees above normal but could be limited somewhat if the wedge
lingers through peak heating. Rain chances will gradually taper off
overnight Monday as the front pushes east. Lows will remain ~15
degrees above normal Monday night despite gradually decreasing cloud
cover.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 200 AM EST Saturday...

Key Messages:

1) Drier Conditions Return Tuesday into Wednesday

2) Above Normal Temperatures Linger through Much of the Workweek

3) A Cold Front Increases Rain Chances on Thursday with Drier
Conditions Expected on Friday Behind the Front

High pressure builds in from the north on Tuesday, lingering through
Wednesday. This will allow dry conditions and mostly sunny skies to
return to the forecast area. Highs will remain well above normal on
Tuesday, dropping to near normal on Wednesday. Lows Tuesday night
will end up several degrees above climo despite good radiational
cooling conditions. Cloud cover will gradually increase Wednesday
night ahead of the next cold font, keeping lows several degrees
above normal. The cold front will push across the forecast area
overnight Wednesday into early Thursday morning, potentially
bringing rain chances back into the forecast. However, the latest
global model guidance is trending drier so capped PoPs to chance
Wednesday night into Thursday. Sfc high pressure builds in from the
west behind the departing front on Friday leading to drier weather.
Highs will rebound to above normal values Thursday into Friday, with
lows remaining several degrees above normal through the rest of the
long term.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Backdoor cold front settling thru the area
will introduce considerably drier air this morning and set up a
CAD-like wedge regime, with winds picking up from the NE at all
sites except KAVL by daybreak, where not already. KAVL will see SE
winds develop around daybreak and remain so thru the rest of the
period. Ahead of the front, a band of mostly low VFR stratocu will
shift south, occasionally being seen at KGSP/KGMU/KAND. Sfc dewpoint
depressions remain small in the southern part of the terminal
area, such that KAND will see fog until sufficient drying occurs
10-12z. A few gusts are likely during the day. E`ly flow aloft will
keep mainly FEW-SCT stratocu in place today but some VFR cigs are
possible this morning in the Upstate. Alto/cirrus will increase,
and by evening warm upglide over sfc high will begin to produce
cloud cover, which may result in MVFR cigs in some areas by daybreak
Sunday, a mention which could need to be made in the next TAF set.

Outlook: Additional showers and associated restrictions are possible
Sunday and into early next week as another wedge pattern develops
over the western Carolinas.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...Wimberley
SHORT TERM...AR
LONG TERM...AR
AVIATION...Wimberley