Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 250708

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
308 AM EDT THU AUG 25 2016

High pressure will persist over the region today with another weak
surface front approaching the Western Carolinas from the northwest
later tonight. High pressure will build back to our north in the wake
of the front on Friday and linger through the weekend. A tropical
low will strengthen off the southern tip of Florida early next week
and then make its way towards the northern Gulf Coast.


As of 300 AM EDT...The center of a 596 dam high at 500 mb will shift
northeast over our area today, keeping the area relatively
suppressed. Despite this, the operational guidance indicates there
should be more instability across the high terrain today, thanks to
steeper mid level lapse rates under the high. And the latest CAMs do
show convection firing across mainly the NC mountains this
afternoon. Steering flow will be out of the northeast and should
keep most of the activity from reaching the piedmont. So PoPs will
feature slight chance to mid chance in the mountains and adjacent
foothills, while the piedmont remains dry. Convection is not
expected to be severe today, with modest CAPE, weak shear, and low
DCAPE. Morning clouds should scatter out more readily than
yesterday, and allow temps to bounce back to normal or a category

Tonight, convection should wane quickly after sunset. There will be
some lingering mid and high clouds like last couple night. So temps
will be held a category or two above normal. Patchy fog will also be
possible, especially in the mountain valleys.


As of 3 AM EDT Thursday...the short term fcst picks up at 12Z
on Friday with broad upper ridging in place over the SE CONUS and
broad trofing over the Northern Rockies. The ridge will remain
in place thru the period with some flattening expected as we move
into the later part of the weekend. In addition, a tropical low
is expected to strengthen off the SE coast of Florida by the end
of the period and will need to be closely watched going forward.
At the sfc, an area of pre-frontal moisture will lift to our NE
early Friday with most of the deeper moisture remaining north of
the CWFA. As the front lifts farther NE late Friday and Saturday,
another high slides across the Great Lakes and then over southern
Quebec. By the end of the period early Sunday, the tropical low
will likely be centered near the southern tip of Florida with its
deep moisture shield still well to our south. As for the sensible wx,
the period still looks mostly dry with the best chances for scattered
convection over the higher terrain each afternoon/evening. Temps start
out well above normal for late August and cool a few degrees by the
end of the period on Sunday.


As of 250 AM EDT Thursday...the medium range fcst picks up at 12Z on
Sunday with broad upper ridging centered over the Atlantic Coast
and a tropical low approaching the southern tip of Florida. As we
move into early next week, the upper pattern flattens across much
of the CONUS as the polar jet remains well to the north. The main
feature of interest will be the tropical system that develops over
the Bahamas and makes its way into the Gulf of Mexico. At the sfc,
high pressure will be moving off the northern New England Coast as
the aforementioned low develops off the SE coast of Florida. The ECMWF
currently keeps the low on a more eastern track and has it moving up
the west coast of Florida and then over Georgia before curving back
to the NE and moving up the Carolina Coast. The latest 00Z run of the
GFS struggles to develop the sfc low and also keeps it near the Florida
Coast. The Canadian Model moves the system farther west and has it
making landfall in the vicinity of Mobile, AL. With these continued
discrepancies, it is still too early to have much confidence in any
particular solution. As for the sensible fcst, no major changes were
needed with below climo POPs for Sun and Mon and near climo POPs for
Tues and Wed. Temps are expected to remain about a category above normal
thru day 7.


At KCLT and elsewhere...Other than some possible fog at
KAVL/KHKY/KAND up until just after sunrise, VFR conditions are
expected today. Cirrus continues to stream in from the north, as a
large area of high pressure persists across the Deep South. Winds
will be light and rather variable through the period. Patches of
high-based cumulus will give way to slightly lower convective cu
this afternoon. Guidance shows better chances for mountain
convection. Will keep the PROB30 at KAVL. The Piedmont looks to
remain dry today.

Outlook: A deep ridge will remain in place over the Southeast thru
the weekend, keeping afternoon SHRA/TSRA chances below normal each
day, and generally confined to the mountains. However, sfc moisture
will gradually return, and morning vsby restrictions will become
increasingly likely during this time.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High  93%     High 100%     High 100%     High 100%
KAVL       Med   74%     High  92%     High 100%     High  93%
KHKY       High  88%     High 100%     High 100%     High 100%
KGMU       High  93%     High 100%     High 100%     High 100%
KAND       High  83%     Med   70%     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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