Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 171735
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
135 PM EDT Sun Mar 17 2024

.SYNOPSIS...
Drier and cooler conditions will return Monday and Tuesday as
Canadian high pressure builds over our region. Warmer temperatures
will move in by mid-week with lingering dry conditions. A low
pressure system will bring rain chances back on Friday and lingering
into Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
1230 PM Update...The fcst remains in good shape at this hour.
Clearing has commenced more widespread and a little sooner than
anticipated, so have made lowering adjs to the Sky grids. Max temps
still on track to reach l70s east of the mtns and mid to upper 60s
mtn valleys.

Previous Forecast...Over the next 24 hours, the confluent zonal flow
aloft will gradually become more cyclonic as a short wave drops down
across the upper and mid-MS Valley region. Two weaker srn stream
short waves embedded in this flow will move across the region...one
early in the day and one late in the day...the latter with some
upper support from the right entrance region of a jet streak moving
past to the north this evening. The second wave will bring a
reinforcing cold front eastward across the fcst area in the evening.
An increase in mostly mid-level cloudiness is a given for today.
Several of the CAMs bring light precip mainly over the srn half of
the fcst area during the day, and that looks like the right call
based on the radar trend. The extensive clouds and light precip
should keep temps a few degrees cooler than yesterday, but still
more than five degrees above normal. For tonight, behind the front,
temps will fall back close to normal as high pressure starts to
build in from the west. The coldest air should remain off to the
west through daybreak Monday.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 200 AM EDT Sunday: No major changes for the short term
forecast period. Cool Canadian high pressure will filter into the
central and southern US Monday into Tuesday leading to drier weather
and below normal temps across the western Carolinas and northeast
Georgia. Highs will end up around 5-8 degrees below climo on Monday
and 3-8 degrees below climo on Tuesday. Lows Monday night into early
Tuesday morning will be around 8-10 degrees below climo and near or
below freezing across the CWA. Since the growing season has started
across Northeast Georgia (outside of Rabun and Habersham Counties),
the SC Upstate (outside of the SC mountains), the southern NC
Foothills, and the southern NC Piedmont, a Freeze Watch was issued
for these areas. This will likely be upgraded to a Freeze Warning if
model trends hold regarding freezing temps. Lows Tuesday night will
be around 10 degrees warmer so additional freeze products should not
be needed. A tight pressure gradient will lead to breezy NW winds on
Monday across the forecast area, but they look to remain below
advisory criteria for now. Winds will gradually decrease in speed
Monday night into early Tuesday morning, but lingering wind gusts
are expected across the NC mountains. Winds pick up again slightly
Tuesday into Tuesday night, especially across the mountains.
However, wind speeds should generally be lower compared to Monday.
The dry airmass combined with breezy winds each afternoon will lead
to fire wx concerns on both Monday and Tuesday. RH values look to
drop into the low to mid 20s east of the mountains on Monday, and
the upper teens to mid 20s across much of the forecast area on
Tuesday.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 230 AM EDT Sunday: No major changes for the first half of the
long term forecast period. Above climo temps return middle of the
week despite a dry cold front tracking across the forecast area on
Wednesday. Low-end wind gusts will linger across the NC mountains on
Wednesday, with gusts returning in the late morning/afternoon hours
elsewhere thanks to the cold front. RH values will recover somewhat
Wednesday afternoon, but are still expected fall into the mid to
upper 20s east of the mountains. Thus, fire wx concerns will return
once again Wednesday afternoon. Wind gusts will finally taper off
area-wide throughout Wednesday evening. Dry high pressure builds in
from the north behind the departing front on Thursday. This will
lead to slightly cooler temps on Thursday compared to Wednesday.
With winds gradually turning SE Thursday afternoon, RH values should
climb into the upper 20s to lower 30s east of the mountains. Since
winds will be lighter on Thursday, this should limit fire wx
concerns.

A low pressure system lifting NE out of the Gulf Coast may bring
rain chances back to the western Carolinas and northeast Georgia the
second half of the long term. A sfc high passing to the north may
also allow cold air damming to develop east of the southern
Appalachians on Friday ahead of the low. The 00Z GFS and Canadian
continue to trend wet, but the 00Z ECMWF is now showing dry
conditions across the CWA. Per model disagreement, capped PoPs to
chance Friday into Saturday. Instability still looks to be lacking
with this system, especially with CAD in place, thus maintained the
no thunder mention at this time. Highs look to end up below climo on
both Friday and Saturday thanks to precip, cloud cover, and the
wedge.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: A broad sfc trof will continue to cross the
area this afternoon with little moisture as drying hipres works in
from the west. Expect little in the way of llvl clouds thru the
period with the majority remaining in the mid to upper levels. As
the high pushes in overnight, expect a tightening p/grad and sfc
winds will remain elevated enuf to offset a morning fog threat. VFR
conds continue thru the latter period with low-end nw/ly gusts
outside the mtns and likely more moderate gusts remaining at KAVL.

Outlook: VFR conditions are expected for the early to middle part
of the week.

&&

.FIRE WEATHER...
A dry atmos will continue to engulf the area Mon as a strong upper
trof approaches from the northwest. This trof will usher in a little
cooler temps and afternoon mixing heights will decrease, however,
expect dry air within this layer to mix to the sfc during the
afternoon to create RH values arnd 25% or less mainly east of the
mtns, yet some mtn valleys may also see quite low RH levels. This
trof will also increase winds within the sfc-layer with gusts
reaching 25 mph or higher across NE GA, the wrn Upstate, as well as
the NC mtns. Due to the uncertainty with higher winds overlapping
spatially with the lower RH values, will coordinate with
State/Federal land managers on subsequent shifts for the type of
fire weather products to be issued.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Freeze Watch from late Monday night through Tuesday morning
     for GAZ018-026-028-029.
NC...Freeze Watch from late Monday night through Tuesday morning
     for NCZ068>072-082-508-510.
SC...Freeze Watch from late Monday night through Tuesday morning
     for SCZ008>014-019-104>109.

&&

$$

SYNOPSIS...AR
NEAR TERM...PM/SBK
SHORT TERM...AR
LONG TERM...AR
AVIATION...SBK
FIRE WEATHER...SBK


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