Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 262341

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
741 PM EDT THU MAY 26 2016

Moist southerly flow will lead to warmer temperatures and mainly
afternoon chances of showers and thunderstorms through Friday. A
period of cooler and wetter weather may develop late in the weekend
as Atlantic low pressure moves toward the South Carolina coast.


As of 730 PM EDT Thursday...a few showers and storms persist at
time, and this should dwindle after sunset.

That said however, as the upper weakness sort of stalls over the
region, all the models have an area of mid-level moisture drifting
NW across the Southeast as the surface high strengthens somewhat
overnight. As this area of moisture is lifted over the Southern
Appalachians, pretty much all the near-term models allow at least
showery activity (if not thunderstorms) to continue overnight,
especially into GA. With that, have continued slight chance PoPs
especially across SW zones overnight.

Surface high over the western Atlantic strengthens Friday as a cold
front approaches from the west. The front will be lifted over the
upper ridge and instability won`t be quite as high across the
Piedmont, so for now best PoPs remain over the mountains Friday
afternoon. Temperatures tomorrow should be pretty similar to those
today with not much change to thicknesses, with also very little
change to overnight lows tonight from those last night.


At 230 PM Thursday, on Friday evening an upper ridge will be over
much of the east coast, while an upper trough will be upstream over
central and wester USA, and an upper low associated with a potential
tropical system will be northeast of the Bahamas. The models move
the coastal upper low to the SC coast by Saturday evening, while the
upper ridge weakens over the western Carolinas and northeast
Georgia. The upper low is shown to move very little over coast SC
through Sunday.

At the surface, moisture is expected to remain over the western
Carolinas and northeast Georgia on Friday evening, while areas to
the east remain dry ahead of the approaching coastal surface low.
the drier air appears to spread west over our area by Saturday
morning, persisting through the day. By Saturday evening the models
bring moisture associated with the surface low inland toward our the
southeastern portion of our area, spreading it toward the mountains
by Sunday morning, and then over the mountains during the day.
Instability will be waning Friday evening, and and modest at best
until Sunday afternoon, when instability increases over the
Piedmont. Precipitation will be rather reserved due to limited
vertical lift, and maximized mainly over the mountains.

Temperatures will initially run slightly above normal under the upper
ridge, then will exhibit a slightly reduced diurnal range as the
moisture arrives.


As of 145 PM Thursday...Forecast confidence remains below avg for
the ext range. The op models continue to diverge wrt the track of
the eventual subtrop or trop low beginning Sun night. The GFS has
had varying ideas with this system and now brings the low onshore
north of Charleston. The track thereafter is odd looking with a jog
to the SW then up the SRV as it gets caught up in a broad ulvl trof.
The EC on the other hand has been consistent with keeping the low
track aligned along the Atl shoreline as a more acute s/w pulls it
NE of South Carolina through the period.

The GFS soln would be quite moist and more unstable than the EC the BR area would see prolonged moist upslope flow likely
leading to hydro issues. Scattered afternoon and overnight general
thunder is probable in a deeply moist theta/e column with the
passage of any mlvl pockets of dpva. With the GEFS mslp spread
reaching high levels by Sun eve...the GFS op soln will be given less
weight than the EC. Thus...will continue with chance pops non/mtns
and low likely pops across the BR escarpment through the period. Max
temps could be tricky as well with varying direc/intensity flow and
airmass mixes possible. For now...will keep most the FA a little
below normal with the ne/rn zones a couple degrees below that. Mins
shud avg a few degrees above in high column rh and nocturnal


At KCLT and over next 24 hours looks very
similar to today, so persistence pays. Will include a VCTS at KAND
for the first hour owing to a storm seen on radar nearby, otherwise
only convective debris with a light SW or variable wind.
Intermittent cloudiness should continue overnight. Fog is possible
at KAVL/KHKY owing to precip falling this afternoon. Another round
of SHRA/TSRA expected tomorrow afternoon mainly over the mtns, so
for now have only introduced PROB30 at KAVL and KHKY. S to SSW winds
through the period around 5kt, with LGT/VRB overnight.

Outlook...Mainly VFR conditions will prevail through the period, but
patchy morning fog chances continue at KAVL. Scattered afternoon
SHRA/TSRA coverage will return on Sunday, with increasing chances
into early next week.

Confidence Table...

            23-05Z        05-11Z        11-17Z        17-18Z
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%     Med   75%     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 schedule 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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