Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 260733
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
333 AM EDT Tue Mar 26 2024

.SYNOPSIS...
Rain will return today ahead of a cold front approaching from the
west.  Low pressure will develop along this front, keeping rain in
the forecast through early Thursday, before drying high pressure
arrives for the weekend.  Dry and warm weather is expected Friday
into Sunday, before a possible pattern change on Monday leads to
cloudier and possibly rainier weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
Upper level heights become more diffluent and lower thru the period
associated with a stg h5 trof swinging across the Midwest and GLakes
region. Ongoing convec is fairly robust with an associated cold
front pushing thu middle TN and central AL. This front will work
into the FA this afternoon and interact with sfc ridging to produce
widespread rainfall thru the period.

Expect the sw/rn NC mtns and far NE GA to see rounds of light rain
this morning arnd daybreak as upslope flow increases and llvl
moisture is maintained from the ATL mixing with GOM moisture flux
this afternoon. The better rainfall rates will occur this afternoon
into the evening as upper forcing increases and the sfc trof crosses
east. Instability is still looking meager with this system as mlvl
lapse rates remain below 6 C/Km and sbCAPE is virtually non-
existent. However, soundings do indicate a period of muCAPE arnd 300
J/kg this afternoon and into the early overnight across the srn most
zones, which may generate a few general tstms and brief localized
heavy rainfall and gusty winds. The flooding risk is low with this
system as storm total rainfall amts will generally range from 1.5
inches across the srn BR to arnd a quarter inch over the far ne/rn
zones thru Wed morning.

With a highly moist atmos lingering thru the period, high temps will
remain cool arnd 10 degrees below normal. Mins will only drop off
about 10 degrees with lows in the m40s across the mtn valleys and
arnd 50 F east of the mtns.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 301 AM EDT Tuesday: No major changes to the forecast in
the short term.  By Wednesday morning, leading upper disturbance
will have long since merged with the mean flow aloft...leaving a
strong longwave trough spanning most of the CONUS.  There`ll be
little in the way of upper forcing through much of Wednesday,
while a faltering frontal circulation over the central Carolinas
will struggle to produce more than token QPF over the far
eastern parts of the forecast area...primarily east of I-77.
Wednesday night, a compact shortwave embedded in this flow will
lift out of the Gulf of Mexico and ride up the frontal boundary,
spurring development of an open wave on Thursday.  The latest 00z
suite of operational guidance has trended downward in terms of QPF
response...producing little return flow in favor of stronger CAA /
high pressure on the back side of the front...so in general Thursday
now looks like more of a transitional / improvement day...with
clear skies and an uptick in postfrontal winds by Thursday night.
Temperatures on Wednesday will be a little above normal...falling
at least to normal, maybe a couple degrees below normal on Thursday
in light of stronger low-level CAA.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 329 AM EDT Tuesday: High pressure will dominate the forecast
through the weekend.  Broad and weak ridging will set up over the
eastern two-thirds of the CONUS, steering expansive high pressure
from the central Great Plains across the Deep South / Gulf Coast and
eventually, out to sea.  Temperatures will rise into the 70s again
on Saturday and Sunday...probably hitting 80 across the Upstate.

Operational guidance is in increasingly good agreement on this
ridge resulting in more of a blocking setup than previously
depicted...and this holds any backdoor front mostly north of the
region late Sunday into Monday.  There`s still a camp within the
broader ensemble guidance that brings some rainfall into the area on
Sunday night and into Monday...but at this point, couldn`t justify
more than token QPF mention along the far northern zones, north of
I-40, where the steep terrain of the northern NC mountains might
interact with some anemic moisture to produce some measurable rain.
Consequently...if current trends hold there`ll be no air mass
change, and temperatures will stay well above normal into the
start of next week.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Flight conds will deteriorate thru the TAF
period as an active cold front crosses east. VFR/MVFR restrictions,
mainly due to CIGS, will lower to MVFR arnd daybreak with light rain
in the vicinity west of I-26. By the afternoon deeper moisture and
more widespread -shra will affect all sites and CIGs will continue
to lower back and forth IFR to MFVR into the evening. More prominent
rain overnight thru the period as a sfc trof tracks east and expect
prevailing IFR to LIFR CIGS with VSBY lowering into MVFR/IFR.
Included a LLWS at KAVL aft 17Z with passage of pre/frontal llvl jet
low enuf to increase 2 Kft AGL winds sigfnt/ly across the higher
terrain. Winds remain generally ne/ly across the Upstate terminals
within a sfc ridge, while KCLT winds align more ese/ly or se/ly. Not
a great gust potential day due to shallow mixing, however, KAVL will
see periodic low-end se/ly gusts thru mid-day.

Outlook: Unsettled shower activity with flight restrictions may
linger into Thursday especially along and east of I-77. VFR conds
return across all sites Fri into the weekend.

&&

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

&&

$$

SYNOPSIS...MPR
NEAR TERM...SBK
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...SBK


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