Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 231754
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
154 PM EDT Thu Mar 23 2017

.SYNOPSIS...
Cooler air lingers across the region through the end of the work
week. A warm and moist southerly flow develops this weekend as high
pressure moves off the coast and a cold front approaches from the
west. This will bring showers and thunderstorms into the area by
Sunday, which continue into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 135 PM EDT...mostly clear skies are prevailing across the fcst
area with strong high pressure anchored to our NE. The rest of the day
should remain dry with high temps expected to remain well below climo
and RH values bottoming out in the 25 to 30% range for most locations.

Tonight, as low-level high pressure drifts off the coast, southerly
flow will increase atop the CWFA, tapping into a little Atlantic
moisture. Both the NAM and GFS show some increase in stratus across
the Upper Savannah Valley, and possibly spreading up the Piedmont
overnight. So I will advertise an increase in clouds across the
western two-thirds of the CWFA by daybreak Friday. The depth of
moisture doesn`t look deep enough in the time-heights to support
precip. So will continue a dry forecast overnight. Min temps will be
at to slightly above normal.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 215 AM EDT Thursday: An upper ridge axis moves into the area
Friday then slides to the coast Friday night. The center of surface
high pressure wedged into the area from the NE in cold air damming
pattern moves out into the Atlantic with the ridge taking on an
east-west orientation. This allows a moist southerly flow to begin
to develop creating isolated showers near the Blue Ridge along the
NC/SC/GA border. Highs Friday will be near to a little above normal.
Lows Friday night will be 5 to 10 degrees above normal.

An upper low moves into the mid MS valley Saturday and into the OH
valley Saturday night as a short wave rotates around the upper low
and into the TN valley. The surface ridge breaks down as a cold
front associated with the upper low moves toward the area. This
creates a stronger moist southerly low level flow. Deep moisture
moves in as well along with synoptic scale forcing. Precip chances
will slowly increase Saturday with best chance along the southern
Blue Ridge, but then quickly increases Saturday night with best
chances over the mountains and foothills. Highs will be 5 to 10
degrees above normal with lows 10 to 15 above normal.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 345 AM EDT Thursday: Guidance remains in good agreement during
the medium range. The upper low moving east in the short range moves
into the Mid-Atlantic on Sunday swinging the associated short wave
across our area. Deep moisture and synoptic scale forcing move
through as well as a cold front approaches from the west. Precip
chances increase as a result then slide east Sunday night with the
short wave. There will certainly be enough instability and forcing
for thunderstorms to develop. Shear increases as well. This combined
with the forcing may be enough to produce isolated severe storms.

Precip chances continue Monday and Tuesday as another, albeit
weaker, upper low and associated short wave crosses the area. Again,
there will be enough instability for thunderstorms to develop.
However, with the weaker upper system, shear is much less with a
much lower severe storm chance.

Ridging builds in surface and aloft on Wednesday bringing an end to
precip chances. Temps 5 to 10 degrees above normal Sunday rise to 10
to 15 degrees above normal through the end of the period.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
At KCLT and Elsewhere: VFR conditions expected through the TAF
period except for some brief MVFR cigs at KAND late tomorrow
morning. Cloud cover should gradually expand eastward across the
region tonight and into tomorrow. Winds should become SELY over the
next few hours and remain weaken later tonight. Some sites could see
winds back somewhat again tonight, especially across the Upstate to
ENE, but they should remain SELY to SLY at KCLT thru the rest of the
period. A few low-end gusts are possible at KAND over the next few
hours, otherwise prevailing winds should remain 10 kts or less thru
the period.

Outlook: increased low level moisture returns from the south tonight
thru Friday, resulting in increases in sky cover. Some cig restrictions
are possible Friday and Saturday mornings, especially near the Blue
Ridge escarpment and portions of the SC Upstate. Increased precip chances
return Saturday thru Sunday.

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 100%     High  88%
KAVL       High 100%     High 100%     High 100%     High  95%
KHKY       High 100%     High 100%     High 100%     High  96%
KGMU       High 100%     High 100%     High 100%     High  88%
KAND       High 100%     High 100%     High 100%     High  82%

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...RWH
NEAR TERM...JPT
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JPT



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