Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS62 KGSP 241409

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
909 AM EST Fri Nov 24 2017

Dry high pressure will remain over the region into early Saturday.
A fast-moving cold front will move through the area Saturday afternoon
and may bring a few showers to the mountains. In the front`s wake,
another round of dry high pressure will overspread the region and
persist into the middle of next week.


As of 900 AM Friday...After an ideal radiational cooling night,
temperatures are a tad slow warming up this morning as current obs
are reading mainly 30`s/around 40 attm. Other than minor adjustments
made to the progression of temperatures over the next few hours, no
major adjustments needed for going forecast. A few sites
continue to report fog this morning, but expect this will
dissipate within the next hour or two.

Otherwise, surface low pressure centered east of Jacksonville, FL
this morning will move northeast away from the coastal Carolinas
through the day. Meanwhile, an upper level trough axis along the
Appalachians will move east to the coast today as the upper flow
pattern gradually deamplifies and then becomes more zonal through
tonight. A little cirrus may arrive on the westerly flow aloft
tonight. Temperatures should recover to slightly above climatology
in most areas for afternoon maxes and overnight mins.


As of 320 AM EST Friday: the short term fcst picks up at 12z on
Saturday with very broad upper trofing digging down across the Great
Lakes and most of the Eastern CONUS, while equally steep upper
ridging builds over the Western CONUS. This overall pattern will
remain largely in place thru most of the period, although heights
will begin to recover on Monday as the trof axis lifts northeast
and the ridging spreads farther east. At the sfc, a cold front
will be approaching the fcst area early Sat and is expected to move
thru the CWFA by early Sun. Another round of dry high pressure
overspreads the area in the front`s wake and lingers well into the
extended period. As for the sensible fcst, the period should be
mostly dry. The overall moisture profile of the Saturday front is
shallow with only a few hundreths of a inch of QPF possible over
the higher terrain. Temps will climb above climatology on Sat and
cool back down to near normal, if not a degree or 2 below, on Sun.


As of 2 AM EST Friday: the extended fcst picks up at 12z on Monday
with broad upper trofing moving off the New England Coast and upper
ridging building over the Great Lakes and Miss River Valley. By early
Tues, the ridge will flatten out as it moves over the southeast and
another northern stream upper trof will move rapidly eastward across
Ontario and Quebec. At the same time, a southern stream H5 low will
close off over the SW CONUS and Southern Rockies. This low will lift
northward as it approaches our area late Wed into early Thurs and
open up into a weaker shortwave as it moves over the region. The
feature is expected to move offshore by late Thurs/early Fri. It`s
notable that the 12z ECMWF is nearly 24hrs slower with the progression
of the feature compared to the GFS and Canadian models. At the sfc,
broad high pressure will be in place over the region to start the
period. The center of the high is expected to drift offshore late
Tues, as a fast-moving cold front moves across New England but
remains well to our north. On Wed, the models try to develop a weak
low over the Southern Plains and then lift the system NE towards
the Ohio River Valley. If this pans out, the low would bring a weak
cold front to our doorstep by the very end of the period, early Fri.


At KCLT and elsewhere: Light to calm winds and clear skies will
continue through the morning hours. Some patchy valley fog could
form in the southwest NC mountain valleys and also near lakes, such
as Lake Wylie near KCLT, toward daybreak. Anticipate KCLT remaining
out of the best fog area, but KAVL could see brief restrictions
through 13Z. Otherwise, VFR conditions are expected through the
period. Light southerly flow should develop through the day, with
FEW to SCT cirrus encroaching from the west the latter half of the

Outlook: Expect mainly VFR conditions through the forecast period as
generally dry and cool conditions prevail.

Confidence Table...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High  88%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High  91%
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:




AVIATION...HG is the U.S. government's official web portal to all federal, state and local government web resources and services.