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 131049

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
649 AM EDT Fri Oct 13 2017

A wedge of cool high pressure today will bring some precipitation
today before drier and warmer conditions return over the weekend. A
more robust cold front will approach the Carolinas Sunday night,
bringing a chance of showers to the area Monday. Considerably
cooler and drier air will spread over the region in the front`s
wake and linger through most of the next work week.


As of 645 AM EDT: Numerous showers across the NC Foothills and
Piedmont will move out of the area this morning. That said, patchy
drizzle or light rain could linger, especially near the Blue Ridge
into the afternoon. Hybrid cold air damming strengthens across the
area today. Very moist low level conditions in the vicinity of the
low level ridge will support widespread low clouds through the day.
Precip chances decrease and retreat to along and near the Blue Ridge
where upslope flow continues. The parent high is forecast to become
centered near Nova Scotia during the day, so the damming will have
some difficulty locking in. Still, extensive low cloud cover is
expected to persist through the day, and this alone should be
sufficient to bring max temps back down to near normal levels.

The center of the parent high moves into the Atlantic tonight, but
ridging remains in place across the area. The low level flow becomes
increasingly unfavorable for precip and chances, while limited to
along and near the Blue Ridge, diminish through the night. Lingering
low level moisture will keep low clouds across the area overnight
with patchy fog developing. Lows will be 10 to 15 degrees above


As of 230 AM Fri: Weak CAD will still be in place Saturday
morning but appears likely to break down, with the parent high
well offshore; furthermore, diminishing moisture and weak low-level
flow imply partly cloudy to mostly sunny skies for the bulk of the
day. Given the sunshine and deep subtropical ridging over the area,
max temps will return to 5 to 7 degrees above normal.

A developing cyclone over the upper Mississippi Valley will track
into the Great Lakes by Sunday morning. This system will bring a
cold front across the Mid-South on Sunday, but it is not expected
to reach the Carolinas and Georgia until early Monday. For our area
Sunday looks to be similar to Saturday, if not a tad warmer under
the modifying airmass and southwesterly winds; subsidence should
be enough to preclude convection. Cloud cover will increase from
the northwest Sunday night ahead of the front. Guidance overall
has trended earlier in bringing the front into the GSP CWFA,
but there remains some discrepancy between models, and the trends
are not consistent. Peak precip chances based on what looks to be
the most likely timing are around daybreak in the mountains and
at midday in the lower Piedmont. Cold advection is progged to be
sufficient enough to bring max temps back below normal. Winds may
be a little gusty during the afternoon as well.

The sharp cool-down will be particularly notable Tuesday morning.
The same guidance which performed well following the last good fall
front back at the beginning of the month lends confidence to crisp
min temps ranging from the upper 30s in the higher elevations of
the mountains, to the upper 40s in the Upstate, which is about a
category below normal. This is by no means the coldest guidance,
with a few members suggesting the higher elevations will experience
a light freeze. Some frost may develop even assuming the favored
blend verifies.


As of 300 AM Fri: Dry continental high pressure will build in
Tuesday and persist over the area through the remainder of the fcst
period, though there are some model differences as to how it moves
in response to the upper pattern. Nonetheless confidence is high
on dry and seasonably cool conditions with this airmass. Abundant
sunshine will allow modification each day, bringing mins and maxes
up to normal by Thursday. High-elevation frost is a possibility
again Wednesday morning, before the mins warm back into the
40s there.


At KCLT and Elsewhere: MVFR and/or IFR stratus will continue into
early afternoon when MVFR becomes predominant. Do not expect any
significant vsby restrictions this morning. High based MVFR may rise
to VFR before sunset. However, conditions return to MVFR then IFR
overnight. VSBY restrictions more likely overnight with MVFR to IFR
likely. NE wind today becomes light NNE overnight. KAVL the
exception with light S wind becoming light and variable overnight.

Outlook: Restrictions will be slow to erode Saturday morning, but
with some improvement returning through the weekend as drier air
works in under high pressure. Conditions will remain moist enough at
low levels for morning restrictions each day in some areas. A cold
front, with associated showers and restrictions, will cross the
region from the west early next week.

Confidence Table...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       High  81%     High 100%     High  87%     High  87%
KGSP       High  81%     High  91%     Med   72%     Med   67%
KAVL       High  82%     High  81%     High  80%     High  93%
KHKY       Med   79%     Med   76%     High  87%     Med   67%
KGMU       High  81%     High  91%     Med   77%     Med   67%
KAND       Med   66%     High  89%     High  82%     Med   61%

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:




SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...RWH is the U.S. government's official web portal to all federal, state and local government web resources and services.