Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 230750

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
350 AM EDT Thu Mar 23 2017

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.


As of 200 AM EDT...Only minor tweaks to the forecast with this
update for the 06z TAFs. Temps are falling slower than expected, but
there`s plenty of time for the temps to reach freezing in the
warning area.

Surface high pressure will move from the Great Lakes to the
Mid-Atlantic region today. Low level cold advection will continue
through that time, as the high takes on a CAD configuration.
However, while warm advection will ramp up over the high during the
day, it does so without enough moisture for sustained cloud cover,
much less precip.  Therefore it looks unlikely CAD will remain
locked in for long.

With skies remaining only partly cloudy overnight, temps are
expected to dip a few degrees below normal. A light breeze
is progged to persist overnight which should minimize any
frost. However, the northwest NC Piedmont is still expected to
drop below freezing. The Freeze Warning issued by the previous
shift will be expanded to include Lincoln and   counties with the
3 PM package. Despite sunshine, max temps will be held down 6-9
degrees below normal tomorrow as the cold airmass remains in place.


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.


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.


At KCLT and Elsewhere: VFR conditions expected through the period as
dry high pressure builds settles over the Mid-Atlantic. There is a
thin layer of moisture trapped under an inversion around 6 to 7 kft
over much of GA and into the western Upstate. Guidance shows this
persisting thru the period, so periods of low VFR cigs will be
possible in the Upstate sites, especially KAND. Otherwise, patchy
cirrus will stream by within the NWLY flow aloft. Winds will favor
NE thru midday, then veer to SE this afternoon. A few low-end gusts
will be possible at KAND, but otherwise, winds should stay 10 kts or
less thru the period.

Outlook: Low level moisture begins to return from the south tonight
thru Friday, resulting in an increase in cigs. Some restrictions in
stratus may be possible Friday and Saturday mornings, especially
near the Blue Ridge escarpment. Precip chances return Saturday thru

Confidence Table...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     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:


NC...Freeze Warning until 9 AM EDT this morning for NCZ035>037-056-


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