Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 161728

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
128 PM EDT Mon Oct 16 2017

Light rainfall chances peak this morning as a fast-moving cold
front moves through the area.  Dry conditions and below-normal
temperatures will follow the front beginning this afternoon, and
persist through mid-week.  Warmer temperatures will return later
this week as deep-layer ridging sets up over the Southeast US.


As of 1045 AM EDT Monday: Winds have shifted across the area and the
back edge of precip only has a line of counties to go before
clearing. Dewpoints dropping steadily here at GSP, was 64/64 at 7a
now 63/52. Sun coming out should start bringing the temps up, but
KAVL with stout gap wind will struggle to get much warmer than it is
now. Have updated temperature trends (though over max Ts look fine),
reduced pops and adjusted sky cover for current trends, but overall
nothing significant. Should be a nice change from yesterday`s warmth.

Tonight, winds will remain breezy as skies become virtually clear.
Bias-corrected MOS temps did well with the "cold snap" we had at the
beginning of the month, so those were preferred for tonight`s mins.
Conditions should be sufficiently moist for some patchy frost to
form in the mtn valleys and foothills, though wind may promote
enough mixing to keep it localized. Hence no advisory will be raised
at this time; day shift will take a second look.


As of 220 AM EDT Monday: Short wave ridging develops over the
Southeast Tuesday before a weak trof returns for Wednesday. At the
surface, cool and dry high pressure builds in Tuesday and remains in
place for Wednesday. Clear skies and light winds will lead to lows 5
to 10 degrees below normal both nights. This puts the mountain
valleys in jeopardy of frost development both nights and the
Northern Foothills and NW Piedmont in jeopardy Tuesday night. Highs
around 5 degrees below normal Tuesday rise to within a couple of
degrees of normal Wednesday.


As of 305 AM EDT Monday: An upper ridge axis builds over the area
through Saturday. At the surface, high pressure remains over the
area Thursday and Friday before sliding off shore on Saturday. This
results in dry weather with a warming trend. Highs start out
Thursday a couple of degrees above normal and rise to around 5
degrees above normal for Friday and Saturday. Lows start out a
little below normal and rise to a little above normal. The ridge
axis moves to the Atlantic coast or off shore on Sunday as deep trog
develops over the central CONUS. The guidance is in some
disagreement on how this trof develops. Both the GFS and ECMWF
develops a closed low at the base of the trof near the Gulf Coast.
However, the GFS is farther west as the northern stream wave splits
and moves east faster. The ECMWF keeps the streams more coherent and
is farther east with the closed low. This shows up at the surface as
the GFS holding the surface ridge in a little longer keeping our
area dry as the moist southerly flow is farther west. The ECMWF
breaks down the ridge allowing the moist southerly flow to move in
from the west faster. Given the differences, have kept Sunday dry
for now. Lows will be a little above normal with highs around 5
degrees above normal.


At KCLT and Elsewhere: VFR through the period as the MVFR cigs
associated with the departed front/precip shield continue to move to
the E. Some mountain valley fog/low stratus not out of the question,
but should not impact KAVL. Gusty N winds will continue this
afternoon, highest at KAVL where gusts remain generally over 30kt.
Gusts should drop overnight, but winds (still out of the N) pick
back up again around 10kt tomorrow afternoon. Some low-end gusts are

Outlook: Seasonably cool and overall VFR conditions will persist
through the work week.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
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:




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