Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 261848
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
248 PM EDT Tue Mar 26 2024

.SYNOPSIS...
Rain will continue ahead of a cold front approaching from the west.
Low pressure will develop along this front, keeping rain in the
forecast through early Thursday.  Dry and warmer weather is expected
Friday into Sunday. The next cold front slowly approaches from the
Mississippi Valley during the first half of next week as moisture
and cloudiness gradually increases.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 220 pm: The latest water vapor imagery indicates an occluded
cyclone over the upper Midwest...riding up the western periphery of
a strong upper ridge centered along the East Coast...with a broad
area of deep SW flow and warm conveyor belt regime/associated precip
region extending from the GA and AL through the southern/central
Appalachians. The northward deflection of the cyclone (to near
Hudson Bay by 12Z Wed) indicates that the upper flow will remain SW
over the Southeast and Mid-Atlantic through the period, so the
precip region will continue to make only slow eastward progress
across our CWA...likely taking until late evening to reach the I-77
corridor. The cyclone track and its occluding character is
resulting in forcing become increasingly meager across our area...
indeed the precip region is looking increasingly ragged, w/ many
reflectivity "holes" showing up in regional radar imagery.
Nevertheless, some semblance of shower activity should survive
across the CWA to warrant likely to categorical PoPs across much of
the CWA at some point through tonight.

In fact, an area of slowly-evolving height falls is forecast to
begin impacting the Southeast by early Wed, with some indication in
short term guidance that weak surface wave development could occur
along baroclinic zone across the southeast coastal states. This
could result in a bit of a re-invigoration of the precip region
across our eastern zones. Late tonight. Although rainfall rates are
expected to be tame, general .25-.75 inch rainfall amounts are
expected due to the non-progressive pattern...with some amounts in
excess of an inch possible across the southwest mountains.

The occasional isolated TS continues to rear its head across north
GA this afternoon, but instability remains meager and of the
elevated variety. We therefore confine the TS mention to a small
portion of our GA counties this afternoon. Meanwhile, guidance does
suggest a bit of an uptick in (mainly elevated) instability across
the Piedmont late tonight into early Wed, so isolated/widely SCT TS
are mentioned there. Some very weak surface-based CAPE could brush
the southeast zones, but low level shear is forecast to be quite
tame at that point, so even if some surface-based buoyancy is
realized, the severe storm potential will be virtually 0. Elevated
storms could nevertheless locally enhance rainfall rates.

Shower chances will persist into Wed across eastern areas, as the
pattern remains stubbornly non-progressive, and a coastal cyclone
(slowly) gets its act together. Even so, the highest chances for
precip are only 50-60%, mainly east of I-77. The max temp forecast
is very tricky, as drying/deep mixing will likely develop across
western areas, whereas moisture/clouds and even precip could linger
across the I-77 corridor and vicinity. As such, the gradient in max
T could be 20 degrees or more from SW->NE across the area, with
mid-70s likely across the upper Savannah valley and mid/upper 50s
across the northwest NC Piedmont.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 200 PM EDT Tuesday: A broad upper trough will track across the
Southeast Wednesday evening into Thursday evening before pushing off
the Southeast Coast Thursday night into Friday morning. While the
upper trough pushes into the western Atlantic on Friday, upper
ridging will track east across the central CONUS. At the sfc, a cold
front will stall across the western Carolinas Wednesday evening into
early Thursday before finally pushing east Thursday evening into
Thursday night. This will allow PoPs to linger, mainly across the
eastern fringe of the forecast area, Wednesday evening into early
Thursday afternoon. Sfc high pressure will build in from the west
behind the departing front Thursday night into Friday leading to
drier weather. Lingering cloud cover Wednesday night will allow lows
to end up around ~5-8 degrees above climo. Breezy N/NW winds will
develop late Wednesday night into Thursday before tapering off
Thursday evening. Highs on Thursday will end up a few degrees below
climo behind the FROPA and despite gradually decreasing cloud cover
throughout the day. Lows Thursday night should end up near to a few
degrees below climo thanks to good radiational cooling. Highs on
Friday will be several degrees warmer and a few degrees above climo.
Breezy WNW/W winds may return, especially across the northern zones,
on Friday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 230 PM EDT Tuesday: Upper ridging will gradually build across
the eastern US through the long term period. At the sfc, high
pressure will be centered over the Southeast Friday night before
gradually pushing into the western Atlantic on Saturday. The sfc
high looks to linger in the western Atlantic and just east of
Florida the remainder of the long term forecast period. A backdoor
cold front looks to approach out of the north Sunday into Monday and
may increase rain chances for the northern tier of the forecast
area. However, 12Z global model guidance is not in good agreement
regarding the timing/coverage of PoPs late this weekend into early
next week, so confidence remains low regarding precip chances. Thus,
capped PoPs to chance across the northern and western tier of the
CWA towards the end of the period. Lows Friday night should end up a
few degrees above climo. Both high and low temps the rest of the
period should end up ~8 to 13 degrees above climo.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: A region of showers and associated moisture
will slowly overspread the Terminal Forecast Area throughout the
afternoon and into the evening. At least tempo -SHRA conditions,
along with visby of 2-5SM are warranted at all sites. Cigs are also
expected to steadily lower through the afternoon, with MVFR expected
at all sites by late afternoon...and IFR becoming likely by
mid-evening or so. Isolated TSRA will also be possible...mainly this
afternoon near KAND...and early Wed morning near KCLT. At this
point, it appears that only the latter of these two warrants a TAF
mention, with a Prob30 for TSRA carried between 11 and 14Z.
Otherwise, cigs may further lower to LIFR at some, if not all sites
overnight, while visby should remain restricted in BR and/or -SHRA.
Although precip chances will steadily end from the west late tonight
into Wed morning, lingering low level moisture will result in
persistent cig/visby restrictions through much of Wed morning. Winds
will generally favor E or SE at 5-10 kts through this evening,
becoming more NE overnight into Wed morning.

Outlook: Unsettled conditions with flight restrictions and perhaps
scattered SHRA may linger into early Thursday in the KCLT area and
vicinity. VFR conds return across all sites Fri into the weekend.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JDL
SHORT TERM...AR
LONG TERM...AR
AVIATION...JDL


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