Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 270748

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
348 AM EDT Fri Apr 27 2018

An area of low pressure will exit to the northeast of the area
today. A dry cold front will approach from the northwest and cross
the region on Saturday. High pressure will then build in behind the
front Sunday and persist through at least the middle of next week.


As of 345 AM EDT: Precip has moved out and low clouds and patchy fog
has developed over the mountains with areas of dense fog outside of
the mountains. Will issue a dense fog advisory for the Foothills and
Piedmont in NC and all the Upstate and NE GA until 9 AM. The dense
fog may not be quite as widespread across the Upstate or NE GA but
will cover enough of the area for an advisory to be needed.

An upper low will open up early Friday and move out of the area, but
an upper trof axis will not cross the region until after sunset. A
few vort spokes will move overhead to provide some impetus for
shallow convection with some daytime heating on Friday, and the
models develop some weak sfc-based instability. Best chance for
isolated showers will be along and east of the I-77 corridor during
the afternoon. Highs will be a couple of degrees below normal.

Any showers dissipate quickly with loss of heating early this
evening. Skies become mostly clear outside of the mountains, but
some low clouds move back into the mountains overnight on a weak but
moist NW flow. Widespread fog is not expected overnight. Lows will
be right around normal.


As of 315 AM Friday: The last of a series of reinforcing shortwaves
will deepen the persistent eastern CONUS trough on Saturday, pushing
a basically dry cold front across the Appalachians. A few showers
may develop along the TN border, as shallow moisture is lifted in
the NW flow. The GFS has the most QPF response, while the NAM and
Canadian are dry. For now, will keep just a SLGT CHC PoP for
Saturday aftn. The rest of the area will see mostly sunny skies with
near normal temps.

Saturday night thru Sunday night, continental high pressure will
build in from the NW, bringing in slightly below normal temps. Min
temps will be in the 30s in the mountains both nights, and may
warrant a frost advisory and/or freeze warning for some sections.
Highs on Sunday under sunny skies will be about 10 deg below normal
in the mountains and generally 5-8 deg below normal across the
Piedmont. Sunday night looks like the coldest night of the period
with lows about 8 deg below normal.


As of 330 AM Friday: The medium range will feature an upper ridge
building in and persisting across the eastern CONUS with a deep
trough in the west. At the surface, the center of high pressure will
move off the southeast coast for Tuesday and Wednesday. Expect
plenty of sunshine and temperatures warming to just above normal for
this time of year. The above normal conditions will continue into
next Thursday as the high remains in place across the region. A cold
front will approach from the west, but doesn`t look to reach our
area at least thru next Friday.


At KCLT and Elsewhere: Precip ending across the area, but low clouds
and fog are developing in its wake. Expect conditions to become LIFR
overnight with VLIFR outside of the mountains. Expect a relatively
quick improvement generally by 14Z during the morning. Some low VFR
cigs will linger into the afternoon. Isolated showers will be
possible during the afternoon with KCLT having the best chance.
Still too low to include in the TAF for now. Any low clouds outside
of the mountains scatter out during the evening. Low VFR or even
MVFR may move back into the mountains overnight. Light and variable
wind this morning increases in speed becoming WNW to NW into the
afternoon. KAND will see W wind while KAVL sees NNW wind becoming
gusty for the afternoon. Winds diminish during the evening.

Outlook: A dry cold front will approach from the northwest early
in the weekend, with much drier and solidly VFR conditions likely
persisting well into early next week.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       Med   65%     High  89%     High 100%     High 100%
KGSP       Low   47%     High  96%     High 100%     High 100%
KAVL       High  82%     High  90%     High 100%     High 100%
KHKY       Med   63%     High  93%     High 100%     High 100%
KGMU       Low   53%     High  94%     High 100%     High 100%
KAND       Med   62%     Med   78%     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:


GA...Dense Fog Advisory until 9 AM EDT this morning for GAZ010-017-
NC...Dense Fog Advisory until 9 AM EDT this morning for NCZ035>037-
SC...Dense Fog Advisory until 9 AM EDT this morning for SCZ001>014-


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