Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 290728

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
328 AM EDT Mon May 29 2017

Warm and humid air will remain over our region today as high
pressure settles east of the Florida coast. A series of weak cold
fronts will cross the area through mid week. Stronger cold fronts
will the area for the weekend.


As of 320 AM EDT: a cold front will remain just west of the CWFA
thru this evening, as it is roughly parallel to deep layer
west-southwesterly flow. This flow will advect plenty of moisture
into the region, and may limit instability, as some of the debris
cloudiness takes time to dissipate. Guidance generally agrees on
about 800-1500 J/kg of SBCAPE by peak heating, with the NAM the
lowest. Not surprisingly, the NAM keeps the area dry until about 600
PM, then brings convection in from the SW. If we manage to get more
on the higher end of the consensus for CAPE, bulk shear should be
adequate for some organized convection, mainly multicell clusters.
With all that said, it is looking like there`s a risk of a few
severe storms. The new Day 1 Convective Outlook still has a slight
risk for most of the area. PoPs will feature mainly chance to
low-end likely in the SWLY upslope areas. Temps will be a couple
categories above normal.

With the west-southwesterly flow persisting tonight, there may be
some lingering convection will into the evening and overnight. But
overall, PoPs should taper down. Plenty of cloud cover and elevated
dewpts will keep temps above normal.


As of 245 AM EDT Monday: The CWFA remains near the base of a trough
extending south form an upper low over Ontario. This keeps weak
cyclonic flow over the area as the axis of the trough moves in
Tuesday and across the area Wednesday. Expect isolated to scattered
mainly diurnal convection each day. That said, the best chance of
convection will be Tuesday as a weak short wave and upper jet max
cross the area in the cyclonic flow, and a weak cold front moves
through. Severe chances look to be lower than previous days as
instability is weak with shallow lapse rates and moderate at best
shear. Highs will be near normal with lows up to 5 degrees above


As of 255 AM Monday: Zonal flow or flat ridging develops over the
area Thursday and remains in place Friday. Relatively dry high
pressure over the area Thursday will lead to minimal chances of
diurnal convection. The high moves offshore Friday allowing moisture
return to develop leading to scattered diurnal convection. Heights
begin to fall Saturday and Sunday as another upper low develops over
the NE. Waves rotating around the upper low help push a weak cold
front into the area Saturday which stalls Sunday. The increase in
moisture, forcing, and instability results in increasing chances of
scattered diurnal convection each day. Highs remain nearly steady a
little above normal each day. Lows remain nearly steady above normal
as well.


At KCLT: VFR conditions are expected for the most part thru the
period. Because of the rain that fell close to sunset yesterday
evening, there is the potential for a little ground fog around
daybreak. I will add a tempo for 5SM BR. Otherwise, expect just some
thin cirrus and light NW wind thru mid-morning. After that, a
cumulus field is expected with bases around 4000-5000 ft. It should
be more unstable today, and scattered SHRA and TSRA are expected to
develop from mid-afternoon thru the evening hours. Winds should
shift out of the SW, but remain fairly light.

Elsewhere: VFR expected outside mountain valleys, where IFR fog is
developing early this morning. Winds will remain light WSW  or calm
thru daybreak, then increase slightly out of the SW, except NW at
KAVL. A Low-VFR-level cumulus field should around midday. Isolated
to scattered SHRA and TSRA from mid-afternoon thru the evening will
warrant a PROB30 at all terminals.

Outlook: Primarily afternoon and evening TSRA are possible each
day, bringing periodic restrictions. Areas of morning fog and/or
low stratus may potentially develop especially where RA fell the
previous evening. This pattern will continue through at least the
end of the work week.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       Med   73%     High 100%     High 100%     High  98%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High  82%     High  86%     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:




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