Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 250242

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1042 PM EDT Sun Sep 24 2017

Broad, dry high pressure will persist across the region through the
middle of week. Hurricane Maria is expected to remain off the East
Coast through mid-week. A cold front will sweep across the region on
Thursday, bringing drier and much cooler air to the area for
the end of the week and take Maria out to sea.


As of 1030 pm EDT Sunday:  Should be a quiet night with only some
high cirrus to deal with overhead. Temp trend needs adjusting,
but the rest of the fcst is on track.

Otherwise, a broad upper ridge over the eastern CONUS makes gradual
eastward progress as TC Maria moves north.  Maria will remain
off-shore and her impacts to the GSP area will be limited to some
slight enhancement of the northeasterly winds.  Soundings today
and tomorrow are dryer and more capped than previous days, with
any chances for precipitation being below a mentionable level,
even in the mountains.  High clouds from Maria over the area
will gradually increase from few to scattered this evening and
tomorrow.  Temperatures are running very close to model blends,
so will stick with those.  Temperatures today and tomorrow will
be 2 to 3 degrees cooler than yesterday due to some increased in
clouds and continued northeasterly surface winds, but will still
be 5 degrees or so above normal.


As of 155 PM Sunday: The dry and unseasonably warm weather will
persist through the middle of the week, as high amplitude upper
ridging persists over the area. A combination of surface high
pressure centered over the northeast and Tropical Cyclone Maria
moving N toward the NC outer banks will support a sharp surface
ridge over the area, with northeasterly surface winds, which could
become somewhat breezy by the end of the period. Although moisture
may increase to some extent within the circulation around Maria,
especially over the Piedmont, showers would be very unlikely with
subsidence inversion remaining in place across the area. More likely
would be increased high clouds on Tuesday. Therefore, have continued
with the dry forecast. Temps 5 to 10 degrees above normal Tuesday
rise to around 10 degrees above normal Wednesday. That said, high
clouds Tuesday could keep temps across the I-77 corridor a degree or
two cooler than forecast.


As of 145 PM Sunday: For the period starting Wednesday evening,
Hurricane Maria is forecast to be just off the North Carolina coast.
In the mid to upper flow, a series of strong shortwaves are forecast
to cross mid to eastern Canada and Great Lakes region breaking down
the upper ridge which has been giving our region much above normal
temperatures.  The associated cold front crosses our area on
Thursday. With very little moisture accompanying the front, only
slight chance POPs in the forecast for portions of the mountains.
Height falls and cool high pressure will bring temperatures a little
below normal next weekend. Hurricane Maria will quickly be shifted
east and out to sea once the front encounters the tropical cyclone.
A secondary cold front is forecast to cross from the northwest late
Friday and Friday night. The combination of this secondary cold
front and possible development of a low along the primary front near
Florida could bring some rain to mainly southern areas Friday night
and Saturday.  By Sunday, cool high pressure centered over Illinois
will dry and cool weather into the start of next week.

Temperatures will start several degrees above normal Thursday then
drop to near normal Friday then a few degrees below normal through
the weekend.


At KCLT and elsewhere:  VFR conditions for the next 24 hours with
area under a broad ridge of high pressure. Clouds will be limited
to a thin veil of cirrus, mainly over the Piedmont, until mid/late
afternoon Monday when a few stratocu may develop. Fog not expected
to be a problem at any of the TAF sites. Winds should be light
N/NE overnight, and then NE around 10 kt on Monday, except still
N/upvalley at KAVL. Might see occasional gusts at KCLT, so that
was included.

Outlook: Dry conditions expected for the first half of the week.
Under mostly clear skies and calm conditions, fog and/or low stratus
are possible in the mtn valleys each of the next few mornings.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
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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