Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 251052
AFDGSP

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

.SYNOPSIS...
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.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM EDT...No significant changes needed with this update,
as forecast is on track. Updated the winds/sky for the 12z TAFs.

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
above.

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.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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.

&&

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

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere...The 12z TAF period will start out with some
patchy fog around at KAVL/KHKY/KAND, which should burn off within
the first hour or two. From there all sites should be VFR with
periods of cirrus streaming in from the north, and patches of
VFR-level stratocu around. Winds will be light and rather variable
through the period, with high pressure dominating. Patches of high-based
cumulus will give way to slightly lower convective cumulus this
afternoon. Still expect isolated to widely scattered showers and
TSTMS in the mountains this afternoon. So the KAVL TAF will carry
VCTS from 19z to 00z. 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...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       Low   53%     High 100%     High 100%     Med   66%
KHKY       Med   64%     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...JPT
NEAR TERM...ARK
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...ARK



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