Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 091736

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
136 PM EDT Sun Aug 9 2020

We can expect the isolated to scattered showers and thunderstorms
early in the week to become more numerous in the afternoon and
evening from mid to late week.  High high temperatures of a couple
degrees above normal early in the week will be near normal late in
the week under the considerable cloud cover.


As of 130 PM: Main update for the 18Z TAF issuance along with
minor adjustments made to temps/sky/PoPs to coincide with latest
trends as the rest of the near term forecast remains on track.
A few showers and thunderstorms are beginning to pop up per
latest radar imagery attm with otherwise quiet conditions across
the area. Current temperatures are in the mid to upper 80s.

Previous discussion: The synoptic pattern will be characterized by
general bagginess in the upper height field, with a weak short wave
trough forecast to approach the area from the TN Valley by the end
of the day. Forecast instability parameters look very similar to
yesterday...basically typical mid-summer 2000-ish J/kg sbCAPE across
much of the forecast area. Isolated to widely scattered convection
is expected to develop during mid/late across the Blue Ridge, and
perhaps along subtle surface trough draped across the Piedmont, with
overall coverage likely being a bit higher than on Saturday. As
usual, can`t rule out a couple of brief pulse storms producing
microbursts, but it would appear that heavy rainfall will be the
main concern, as conditions are conducive to backbuilding
multicells. Max temps will be a couple of degrees above climo in
most locations.

The approach of aforementioned short wave may be enough to keep
scattered convection going well into the evening, if not the
overnight as seasonably warm/muggy conditions persist.


As of 305 AM EDT Sunday: the short-term fcst picks up at 12z on
Monday with weak, NWLY flow aloft and broad upper ridging in place
across the region. Little change is expected wrt the upper-level
pattern thru the period, as broad upper ridging persists across most
of the CONUS and weak, embedded upper shortwave energy gradually
ripples eastward over the region. At the sfc, on Monday some degree
of moistening is likely as return flow from the gulf gradually
increases thru the day and profiles become more conducive for
convection. On Tuesday, a weak cold front approaches the fcst
area from the NW but stalls out as it lays north of the CWFA late
Tuesday. Although the front is weak and fairly diffuse, it should
provide at least some degree of low-lvl forcing Tues into early
Wed, especially over the higher terrain. Overall, no significant
changes were made to the sensible fcst. PoPs increase to near climo
for Monday aftn/evening and above climo on Tuesday into early Wed.
Temps should be just above normal on Monday and Tuesday, with Heat
Indices remaining below 100 degrees for all but our southern-most


As of 245 AM EDT Sunday: the extended forecast picks up at 12z on
Wednesday with continued weak flow aloft and extensive upper ridging
spread across most of the CONUS. As the period begins the long-range
guidance depicts a fairly robust and embedded upper shortwave moving
over the Mississippi River Valley. This feature is currently much
more well-defined based on the GFS depiction as compared to the ECMWF
or CMC. Regardless, over the next couple of days the shortwave is
expected to track NE and over the Ohio River Valley. Towards the end
of the period the models try and close off whatever is left of the
upper shortwave, however it`s not clear at this point if it will
actually become a closed low. Otherwise, the upper-lvl pattern is
not expected to change much thru the period, with the polar jet
remaining well to the north and over Canada while upper ridging
persists across most of the CONUS. The sfc pattern will remain
fairly messy thru the period with the Bermuda High keeping generally
moist, SLY flow over the region. A weak lee trof tries to develop
on Wednesday as deeper moisture begins to pool over the region.
This pattern will likely continue for the rest of the period as
improving SLY flow brings a resurgence of gulf moisture for Thursday
and beyond. Overall, there were no significant changes made to the
fcst with diurnally-driven, above-climo PoPs each day and temps a
degree or 2 above normal on Wednesday and near normal for the rest
of the period.


At KCLT and Elsewhere: Expect VFR to prevail through tonight with
the exception of intermittent, short-lived flight restrictions in
any shower or thunderstorm that moves over a TAF site, as noted by
TEMPO groups for afternoon/evening convection. Per latest guidance,
isolated showers may linger into the overnight hours, but confidence
on the the potential for -SHRA moving directly over a TAF site is
low attm. Low stratus/fog will be possible before daybreak on
Monday, mainly across the mountain valleys. Otherwise expect VFR
through the end of the valid TAF period.

Outlook: Diurnal convection will increase in coverage each day from
Monday through Wednesday, with above average coverage expected thru
the end of the work week. Morning fog/stratus restrictions will also
be possible each morning, especially over the usual mountain
valleys. Otherwise expect VFR.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High  83%
KAVL       High 100%     High 100%     High  83%     Low   43%
KHKY       High 100%     High 100%     High 100%     High  83%
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 are available at
the following link:




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