987
FXUS62 KGSP 232241
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
541 PM EST Sat Nov 23 2024

.SYNOPSIS...
High pressure spreads over the area this weekend with a gradual
warming trend into early next week. A cold front increases the
chances for brief showers on Tuesday. A second system could bring
rain for Thanksgiving Day and much colder temps toward the end of
the week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 540 pm EST Saturday: The ongoing forecast remains on track and
no changes were needed with this update.

The upper air pattern is forecast to de-amplify through the period,
with a broad trough centered off the East Coast and a ridge axis
progressing east of the Miss Valley by the end of the period.
Resultant (weakening) confluent flow over the East will support dry,
but weakening low level ridge through the period, resulting in
increasingly clear skies, weakening winds and fair weather.
Essentially ideal radiational cooling conditions tonight will result
in min temps of 5-10 degrees below climo in most locations. Despite
the relative dry nature of the air mass, surface dewpoints may be
elevated just enough to support patchy steam fog development along
lakes and in some mountain valleys. A modifying air mass under full
sun in an increasingly westerly low level flow regime and beneath
rising heights aloft will result in a solid warm-up Sunday
afternoon, with maxes expected to be around 5 degrees above normal
across much of the area. The French Broad Valley may be even warmer
than that due to downslope/compressional warming.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Key Messages:

1) A cold front on Monday night increases rain chances, especially
across the mountains.

2) Above normal temperatures.

As of 210 PM Saturday: Picking up on Sunday night, broad westerly
flow aloft with high pressure continuing to build into the region. A
moderate amplifying ridge keeps the area dry Sunday night into
Monday. But the area of high pressure starts to move offshore as an
upper low over central Canada lifts and a somewhat weak cold front
approaches the CWA. Ahead of the FROPA, moisture surges and
increases the chance for precipitation, especially across the
mountains (65%-85%) Monday night into Tuesday. QPF response varies
from a trace in the Upstate to half an inch along the TN/NC border.
Guidance does have the cold front moving through fairly quickly,
diminishing the likelihood of higher precip amounts. Will continue
to monitor. By Tuesday, the front should be through the CWA, with
drier and slightly cooler air filtering in once again. Temperatures
through the short term look to be unseasonably warm and well above
normal.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Key Messages

1) Temperatures decrease through the entire period with colder air
moving into the region

2) Rainy and cold Thanksgiving Day likely

3) NW flow snow along the TN/NC border possible by end of week

As of 215 PM Saturday: The extended forecast picks up on Tuesday
night with a cooling trend for the area. The remnants of a cold
front and drier air starts to mix out Wednesday, but keeping the
area dry. Synoptically, a pattern shift starts to develop with an
extensive and strong continental polar air mass spilling into the
CONUS from Canada. Long range guidance shows the air moving toward
the CWA by the end of the week, increasing precipitation chances for
Thanksgiving Day. At this time, guidance has PoP chances increasing
late Wednesday night (20%-40%) and quickly increasing on Thursday
(40%-65%). As the drier air from the NW filters in, moisture looks
to decrease and rain chances plummet again. Additionally, there is a
chance (40%-50%) for a brief shot of NW flow snow at the TN/NC
border once again on Friday. However, this is at the end of the
forecast period so confidence is low and will continue to monitor
forecast trends. As the colder air mass moves in, winds could
increase across the area, especially at higher elevations but don`t
look to be near advisory criteria at this time. Aside from precip
chances, the temperatures are the other part of the story. This cP
air mass filters in plenty of drier and colder air into the area by
the end of the week and into the weekend. Expect below normal temps
toward the end of the period.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions will prevail at most terminals
through the TAF period. A few high cirrus clouds continue to stream
overhead this evening with light northwesterly winds quickly
becoming calm after sunset. Any restrictions will be due to lake fog
at KAND and KHKY around sunrise as the air temperature cools
significantly below the lake water temperature with calm winds
conducive to fog development. Thereafter, VFR will prevail with
mostly clear skies and light southwest winds tomorrow.

Outlook: A weak cold front may bring scattered rain showers and
associated restrictions on Tuesday. Dry high pressure briefly
returns Wednesday. A more significant storm system may bring
widespread rain and restrictions on Thursday.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...JDL
SHORT TERM...CP
LONG TERM...CP
AVIATION...TW