Area Forecast Discussion
Issued by NWS Greer, SC
FXUS62 KGSP 260238
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1038 PM EDT THU AUG 25 2016
A weak surface front will settle southeast toward the region under
high pressure aloft through Friday. High pressure will rebuild over
the region through the weekend. A tropical low will gradually
strengthen off the southern tip of Florida early next week and then
possibly move toward the Gulf Coast through the week.
.NEAR TERM /THROUGH FRIDAY/...
As of 1030 PM EDT Thursday: Removed all pops on schedule as well
as removing any active wording from the HWO for the evening. Took a
look at the latest temp guidance through the overnight and opted to
blend in the latest mav which effectively raised min temps around a
degree across much of the fcst area given continued mid/high cirrus.
Min temps will likely play a role in areal coverage of patchy
fog tonight, however it still looks as if the best chances once
again reside in the mtn valleys as well as the SC Lakelands region.
Furthermore, wouldn`t be suprised to see patchy fog across portions
of the NC fthills where xover temps are most critical.
Previous Discussion: An upper ridge was located over the southeast
this afternoon, and is expected to move little through Friday. The
models show moisture lingering over our area, with the best moisture
and instability over the Blue Ridge, especially on Friday.
Meanwhile, a weak surface boundary appears to drift south along the
Eastern Seaboard, causing winds to veer from southwest to northeast.
Temperatures will warm from slightly below normal to slightly
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 2 PM EDT Thursday: A 594 dm 500 mb ridge will remain centered
over the Mid-Atlantic region through the weekend. Low level flow
will be mainly easterly south of the mid level ridge axis. This
would seem to permit a very slow uptick in Atlantic moisture across
the western Carolinas, however backward parcel trajectories show a
more mid Appalachian source region for low level air arriving in the
mountains by Sunday. Thus, PoPs will be kept in the isolated to
scattered range for diurnal convection Saturday and Sunday
afternoons. Expect mainly an eastern mountain slope maximum, but
with a secondary maximum possible in weak piedmont surface troughing
and associated low level convergence. Warm mins will remain 8 to 10
degrees above climo, with maxes 4 to 8 above climo through the
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EDT Thursday...the extended period picks up 00Z Monday
with an upper ridge over the southeastern CONUS. Though it is
flattening out by the time the medium range commences, its influence
over the local area will be maintained through the early part of
next week, resulting in precip chances below climo (and limited to
the higher terrain) and maximum temperatures about 5 degrees above
climo. Model guidance diverges at this point with the handling of
the ridge breakdown and the development of a potential tropical
system in the Bahamas, which lends a large amount of uncertainty to
the second half of the medium range forecast. No one global model
has show good consistency over the past 48 hours, so a clear
preference remains elusive and a multi-model blend was again used to
construct the forecast. A frontal boundary does appear to approach
the southern Appalachians by the middle of next week, which provides
a forcing mechanism for convection. If anything, guidance has
trended weaker and slower with the tropical system, with less
moisture transport into our area. Pops were ramped up to above climo
with little diurnal lull on Wednesday and Thursday to correspond
with the influence of the front and the possible influx of tropical
moisture, though a prolonged period of heavy rainfall does not
appear likely at this time.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT: VFR through the period. Low/mid cu to erode shortly
leading into only a few mid/high clouds through the overnight.
Winds will remain light/southerly before increasing and veering
sharply to the nnw around daybreak as parent high pressure
repositions. Otherwise, a dry taf on Friday with low vfr cu
developing amidst continued gradual veering with flow returning
ese near the end of the taf cycle.
Elsewhere: MVFR/IFR and possibly LIFR at all sites aside
for KGSP/KGMU by daybreak associated with fog related visb/cig
restrictions. Otherwise, very similar to that of KCLT above with
light winds gradually veering nnw, around to the ene, then finally
ese by periods end. Mostly mid/high cirrus to prevail through
mid/late morning before low vfr cu redevelops. Did include vcts
mention at KAVL for Friday as instability looks maximized across
the mtns where capping will also be weakest.
Outlook: Deep layer ridging to prevail through the weekend keeping
convective chances below climo levels, with the best probabilities
across the high terrain. Abundant bl moisture could lead to morning
fog/cigs in the mtn valleys each morning, possibly extending into
the piedmont/fthills at times.
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 95% High 100% High 100%
KAVL High 87% Low 45% High 100% High 100%
KHKY High 100% Med 66% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 91% 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: