Area Forecast Discussion
Issued by NWS Greer, SC

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546
FXUS62 KGSP 241801
AFDGSP

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

.SYNOPSIS...
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.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 2pm EDT Sunday:  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.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
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.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
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.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere:  VFR conditions for the next 24 hours with
area under a broad ridge of high pressure.  Convective stability has
improved over yesterday, and even isolated showers in the mountains
are not expected this afternoon or tomorrow.  Winds will be
prevailing northeasterly at 5 to 10kts, assisted slightly by TC
Maria well southeast of the area.  Chances for fog Monday morning
are somewhat reduced as well due to a lack of any precipitation
today and some higher clouds from the TC.  However, the KAVL
aerodrome may still receive a brief period of fog in the morning due
to residual moisture.  Afternoon BL cumulus today around FL040 are
gradually lifting as BL mixes diurnally, and should dissipate around
sunset.

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...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High  87%     High  93%
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:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...DEO
NEAR TERM...WJM
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...WJM



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