Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 231802

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
202 PM EDT TUE AUG 23 2016

High pressure will persist over the region through midweek allowing
temperatures to climb back above normal. Another weak cold front will
approach the Western Carolinas from the northwest toward the end of
the work week, with high pressure building back to our north in the
front`s wake.


As of 150 PM: The CWFA remains under an easterly flow regime
associated with sfc high pressure centered over the Chesapeake Bay
region. A strong subsidence inversion was evident from the 12z KGSO
sounding, and as expected this is keeping deep convection suppressed
over most of the area. The inversion is substantially weaker to
our south and west, however, and a few showers have occurred over
NE GA since late morning. This activity may continue to percolate
thru the heat of the aftn, but RAP profiles suggest the inversion
strengthens rapidly going north and east, and is likely too strong
to overcome beyond the Savannah River counties of SC.

More details to come shortly.


As of 310 AM EDT Tuesday...the short term fcst picks up at 12Z on
Wednesday with mid to upper level ridging building over the SE
region and persisting well into the medium range. At the sfc,
high pressure will be slowly moving off the eastern seaboard on
Wednesday and Thursday keeping a surface wedge over the CWFA. A
fairly broad area of deeper, pre-frontal moisture will pass to
our north during the period. Some of the deeper moisture could
spread over extreme Western NC, however the prevailing wedge pattern
should prevent it from spreading farther east. As for the sensible
wx, most of the convective activity should be limited to the higher
terrain zones during the afternoon and early evening hours. Temps
will start out around climatology and warm thru the period with
highs on Friday about a category above normal.


As of 305 AM EDT Tuesday...the medium range fcst picks up at 12Z
on Friday with broad upper ridging in place over the SE region.
The ridge is expected to remain largely in place thru day 7 with
some flattening likely by the end of the period. At the sfc, a
weak and mostly dry cold front will be moving thru the CWFA early
Friday with another round of high pressure in its wake. The center
of the high will move over the Great Lakes late Fri/early Sat
bringing bndy layer winds around to north and then northeast. The
high eventually lifts north of New England early next week while
another low develops over the Northern Plains. There are some notable
differences between the long range models with the 12Z ECMWF still
developing a tropical low over the Bahamas and moving it over
Southern Florida early next week while the GFS does not develop
a low. As for the sensible fcst, no major changes were needed with
below climo POPs for the period and temps about a category above
normal for late August.


At KCLT and elsewhere: An area of high pressure centered over
the Mid-Atlantic will reinforce easterly to southeasterly flow
over the terminals into Wednesday. Initially some sites (including
KCLT) will see ENE winds, but as that high drifts east, winds will
veer. SCT diurnal cumulus will cover much of the area today, but
subsidence inversion aloft will suppress convection. Overnight,
some guidance (namely NAM/WRF family) brings a moist layer into
SW NC and NW SC. This is a deeper layer than was progged for this
morning, when SCT-BKN low VFR stratocu developed. On that accord,
some MVFR cigs are expected tonight at KAVL and KAND, possibly
slightly further east as well. KAVL and other mountain valley sites
could also see some fog develop particularly if the low clouds are
not as widespread as expected. Expect slightly better convective
chances Wednesday over the mtns, but not until after 18z.

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...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High  93%     High  88%
KAVL       High 100%     High  97%     High  82%     Med   75%
KHKY       High 100%     High 100%     High  83%     High  88%
KGMU       High 100%     High 100%     High  88%     High  87%
KAND       High 100%     High 100%     High  83%     Med   75%

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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