Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 180857
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
457 AM EDT Sun Aug 18 2019

.SYNOPSIS...
A weak area of high pressure will remain across the area today.
Moisture will increase through the first half of the work week, as a
Bermuda high strengthens over the western Atlantic Ocean. A cold
front approaches from the northwest and stalls over the region late
in the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 445 am EDT: Sky cover has been boosted in southwest
sections where low level upglide and upslope moisture is currently
best. Otherwise, the forecast remains on track. The latest surface
analysis reveals a surface low pressure center near the Pee Dee
region of SC. This feature will continue moving northeast along the
coastal Carolinas today. Another low pressure system is developing
over the Florida panhandle and this circulation is expected to stall
over SE GA later today through tonight. Slightly deeper moisture
ahead of this second system may tease the lower piedmont of our
forecast area with better late day moisture. Otherwise, a weak
surface boundary remains stalled near the southeast fringe of the
forecast area today, while weak 500 mb vorticity provides some
triggering over the mountains this afternoon. This forcing setup
will be similar to that observed on Saturday. Thus, anticipate
another round of scattered early afternoon convection developing
along the eastern slopes of the mountains and moving out over the
foothills and Piedmont through the afternoon and evening. Dry mid
levels, with sfc to mid level theta e lapses of 25 to 30 degrees K,
will provide a non-zero severe thunderstorm threat for gusty winds
and marginally large hail this afternoon. The best severe
thunderstorm potential will likely again be in lower piedmont areas
from Charlotte metro to near Abbeville/Greenwood where sbCAPE values
should max out in to the 2000 to 3000 J/kg range there. Weak
steering flow could lead to locally heavy rainfall once again. A few
Upstate and NE GA locations could see heat index values over 100
again this afternoon.

The convection-allowing models show fairly quick dissipation of the
daytime convection this evening, with little more then very isolated
showers expected into early Monday morning. Persistence, to slightly
warmer values, appears a good forecast for temperatures through the
period.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM EDT Sunday: The short term will feature a weakness in
the subtropical ridge persisting over the southeast states. This
will be between two ridge centers, one over the Southern Plains and
the other over the western Atlantic. A weak low is still progged to
develop within this weakness near southern GA or the FL panhandle
Monday into Tuesday. A weak SELY low to mid lvl flow will result
over the FA and should enhance moisture and convective coverage both
days. Instability with be modest, and the shear weak, so a pulse
convective mode is expected with locally heavy rain and isolated
damaging microburst threats. Temps will continue to be slightly above
normal with some humidity.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 330 AM EDT Sunday: The medium range still looks fairly
unsettled, as a long wave upper trough slowly digs over the Great
Lakes to the mid-MS Valley. This will keep high precipitable water
values approaching 2 inches by late week, and suggests that some
locally heavy rain will be possible. A cold front will push in from
the north on Thursday, and should result in our most active day of
the week. The front stalls just to our south, keeping a moist
easterly flow over the area Friday and Saturday. Max temperatures
will be near to slightly below climo, while mins will be near to
slightly above climo due to increased cloud cover and rainfall
potential.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: MVFR clouds have been blossoming around KAND
early this morning in a region of slightly better upglide/upslope
flow moisture. Cannot rule out MVFR making a run to KGMU/KGSP
through daybreak, and also IFR to MVFR approaching KCLT from the
south, but will keep these layers scattered for now.  French Broad
River valley fog and low stratus are expected once again, but lower
restrictions have largely missed the airfield the past two mornings
and that could well continue today. Otherwise, expect developing
cumulus throughout today with heating, and then scattered coverage
of thunderstorms through the afternoon hours. This is currently
handled with PROB30 for TSRA. Surface winds will be light and
primarily southwest during the day, except continued northwest flow
at KAVL.

Outlook: Moisture and instability will gradually increase through
the week, resulting in a steady uptick of afternoon/evening
convective coverage each day, especially mid to late week as a cold
front approaches from the northwest. Morning fog and low stratus
will be possible each day across the mountain valleys.

Confidence Table...

            09-15Z        15-21Z        21-03Z        03-06Z
KCLT       High  95%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       Med   79%     High 100%     High 100%     High 100%
KHKY       High  83%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High  98%

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...ARK
NEAR TERM...HG
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG


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