Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 251503

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1103 AM EDT Sun Jun 25 2017

A cold front will settle southeast of the region today with drier
and cooler air beginning to spread in from the northwest. These
conditions are expected to persist over the forecast area through
much of the week as high pressure remains to our north. As the high
moves offshore, moist southerly flow will return towards the end of
the week.


As of 1055 AM EDT: Cannot rule out sprinkles or very light rain over
the southern tier through mid afternoon as a weak mid level wave
passes overhead. However, profiles are fairly dry and continue to
generally dry out so most locations will stay dry. Clouds are a bit
thicker as well but temperature trends have not suffered a great
deal thus far so will keep the current 70s mountains/mid 80s east
for the afternoon.

Otherwise, a big change starts today in the wake of the departing
cold front. The longwave upper trough axis just to our west will
continue to push east, with thicknesses decreasing as surface high
pressure begins ridging in from the west. The trough will make
little progress through the period, but the airmass change will be
felt in the form of much lower dewpoints, especially tonight. High
temps today will likely be similar to those yesterday (due to less
cloud cover) except maybe in the mountains, though this is still a
handful of degrees below seasonal normals. Overnight lows tonight
will be a good 5 or so degrees below what we`ll see this morning,
and ranging anywhere from 3-8 degrees below seasonal normals.


As of 250 AM EDT Sunday: the short-term fcst picks up at 12z on
Monday with longwave upper trofing centered over the Great Lakes
and steep upper ridging in place over the Western CONUS. By early
Tuesday, an upper shortwave will dig southward on the backside
of the upper trof, providing increased upper-lvl divergence just
ahead of it. The shortwave axis is expected to move overhead Tues
afternoon and then offshore by early Wed with heights beginning
to recover in its wake. At the sfc, a lingering frontal bndy will
be located over the SC Coast early Monday and slowly drift offshore
later in the day/evening. The rest of the period is marked by the
Canadian High sliding SE and towards our area on Tuesday before
ending up just to our north by the end of the period, 12z Wed.
As for the sensible fcst, most of the period should be dry. I do
have some slight chance PoPs on Tues as the upper shortwave
approaches the area and produces favorable ascent especially over
the higher terrain. Temps will be 1 to 2 categories below normal
for late June.


As of 235 AM EDT Sunday: the extended fcst picks up at 12z on
Wednesday with an upper shortwave moving off the Atlantic Coast.
As it does, heights begin to rebound over the fcst area as upper
ridging starts to build to our south. Another longwave upper trof
approaches the Great Lakes on Friday and then gradually slides
to our north over the weekend acting to flatten the ridge to our
south. At the sfc, broad high pressure will be centered just to
our north by early Wednesday with below normal temps in place
over the region. The high will slide off the Atlantic Coast on
Thursday putting the CWFA back under warmer and more moist SLY
low-level flow for the end of the work week. A cold front will
approach the fcst area from the west on Saturday, but is not
expected to move thru the CWFA until the end of the period on
Sunday. As for the sensible wx, Wednesday should be dry with the
high over us. Thurs and Fri will see a return to a more typical
summertime pattern with slight to solid chances for TSRA each day.
Chances for widespread TSRA increase on Sat as the front moves
into the fcst area. Temps and dewpts will start out about a category
below normal and steadily warm thru the period with values reaching
normal by the end of the work week.


At KCLT and elsewhere: VFR has returned throughout as the western
Upstate lake area fog has dissipated late this morning. We will
generally see high and mid level ceilings continuing as a broad
upper trough remains in the place, but with occasional lower
stratocumulus in briefly passing 850 mb moisture. KAND will see the
best chance of a few passing sprinkles. Expect mainly northerly
winds throughout at less than 10 kt, and perhaps a touch higher at
KCLT with the best gradient, and also at KAVL in the French Broad
Valley where low end gusts will be possible as well.

Outlook: Expect light winds and mostly clear skies through Thursday
as high pressure dominates the weather.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
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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