Area Forecast Discussion
Issued by NWS Greer, SC
FXUS62 KGSP 011140
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
640 AM EST Thu Dec 1 2016
Drier and cooler conditions are in store today, and will persist
through Saturday. Moisture should return from the west for the
latter half of the weekend and possibly linger into early next week.
.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM Thu: Cold front has exited the CWFA to the southeast,
leaving cooler/drier air in place for today. Some isolated areas
that saw heavy rain yesterday evening will see patchy fog for
an hr or two after daybreak. Upslope clouds will persist along
the Tenn border as well, but otherwise mostly sunny skies are
expected. Breezy conditions will occur over the mountains (and
occasionally elsewhere too) under cold advective flow. Max temps
will be a category or so above normal, with downsloping offsetting
the CAA a bit. Calmer and still mostly clear conditions tonight
imply good radiative cooling; mins will be close to normal.
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 315 AM EST Thursday: the end of the week looks quiet enough,
for the most part. Nearly zonal flow aloft will gradually buckle as
an upper ridge slowly amplifies to the west on Friday and Saturday.
This will support dry high pressure over the Southeast on Friday
that gradually gets assimilated by another surface high coming
across the Plains on Saturday. Temps both days will be very
similar...slightly below normal.
Changes will take place Saturday night as the upper ridge axis moves
overhead. Expect isentropic lift to spread northeast across the
region along with moisture return from the Gulf, aided by upper
divergence from the right entrance region of a jet streak passing to
the north. Expect that precip will attempt to develop from the west,
at least across the mountains and wrn half of the fcst area in the
pre-dawn hours on Sunday. Think we can fine tune the timing a bit,
based on the SREF and GEFS, to keep precip chances from moving in
until after 00Z Sunday, and to delay the eastward expansion of
likely precip until after 12Z Sunday. Temps are problematic as
initial dry air will allow for boundary layer cooling. Fcst
soundings, in particular the NAM, suggest that precip will reach the
ground as snow at elevations above about 3K feet around daybreak
Sunday, altho the GFS is not as cool. Think a compromise is in order
that would result in some snow chance at elevations above about 3500
feet if precip develops after midnight, but for the time being no
accumulation is expected as precip amts are minimal.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 225 AM EST Thursday: the medium range fcst picks up at 12z on
Sunday with flat upper ridging in place over the southeast and a large
H5 cutoff low over NW Mexico. This low eventually becomes absorbed by
the mean flow and morphs into a decent looking shortwave. The models
have the shortwave passing just to our NW on Tuesday as the upper ridge
steadily amplifies. Ridging is expected to remain in place until the
end of the period with a broad upper trof approaching the fcst area
late in the week. At the sfc, the pattern evolution remains somewhat
uncertain compared to the upper levels. The models are delaying the
development of a Northern Gulf of Mexico low until Monday/Tuesday with
the system not moving to our north until late Tuesday. In the wake of
the low, things dry out on Wednesday. Another cold front appears to
approach the CWFA from the west by the end of the period on Thursday,
but timing varies between the models.
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR as colder/drier air filter in on W to NW
winds; some upslope cloudiness will linger over the mountains near
the Tenn border during the period. Lee troughing appears likely to
bring winds back to WSW at KCLT for a time there this aftn. The
trough also has the effect of keeping winds more westerly at the
other Piedmont sites until this evening, when they veer to NW. Some
occasional gustiness is possible around the area today within the
CAA pattern, but only KAVL should see significant enough gusts
Outlook: Dry high pressure persists over the region thru
Saturday. Precip and restrictions may return as soon as Sunday,
as another cold front moves into the region. There may be a brief
lull in these impacts Monday, before low pressure develops along
the front to our west and brings a second shot of moisture overhead
Mon night into Tue.
11-17Z 17-23Z 23-05Z 05-06Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link: