Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 220713

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
313 AM EDT SUN MAY 22 2016

Dry high pressure builds into our region from the Mississippi
and Ohio valleys early this week as low pressure lingers over
the Mid-Atlantic. A moist southerly flow develops by mid week and
continues into the weekend.


As of 300 AM: Upper trough now centered over the Mid-Atlantic
will deepen over the Eastern Seaboard thru tonight. An embedded
shortwave will swing across the southern Appalachians this
morning. This feature, combined with plentiful low level moisture
and upsloping flow, is generating a layer of low clouds along the
TN/NC border. A few showers are seen on radar within this cloud
deck, but downsloping closer to the Blue Ridge Escarpment is
preventing the clouds or showers from expanding further into the
area. The moisture will diminish going later into the morning. Over
our eastern Piedmont zones a patch of midlevel clouds is expected
to thin and shift east, also following the shortwave.

Mid-level lapse rates remain rather strong this afternoon thanks to
the cooler air within the trough, and another embedded wave enters
the area from the north in the late aftn. Some WRF runs develop
showers over western NC from the combination of these features, so
low PoPs have been maintained there. Winds will be northwesterly and
breezy today with occasional gusts. Max temps will be a few degrees
cooler than those Saturday, 6 to 9 degrees below normal. Winds are
expected to become light and variable tonight, with only spotty
cloud cover, so radiational cooling will be fairly good in the
already cool airmass. Mins will be a couple degrees below normal.


As of 155 AM Sunday, the upper low near the NC/VA coast moves little
on Monday keeping some cold mid level temps across the area. Enough
weak instability develops for some isolated convection to develop
across the northern tier of the CWFA during the afternoon. Little to
no instability elsewhere will keep the forecast dry. The upper low
moves into New England on Tuesday with a ridge axis moving into the
area from the west. Dry high pressure builds in at the surface.
Highs below normal on Monday rise to a couple of degrees above
Tuesday. Lows near normal Monday night rise a few degrees above
normal Tuesday night.


As of 245 AM Sunday, upper ridge remains over the area through the
period, but sharpens by Saturday as an upper low moves northeast
across the Plains. At the surface, high pressure moves off the SE
coast on Wednesday with a southwesterly low level flow developing
and continuing through Friday. The flow could become a little more
southerly on Saturday as a cold front moves into the Plains. Low
level moisture, and the resultant instability, will be greatest
across the mountains until Saturday when the expand into the
foothills. Therefore, have slowly increasing diurnal PoP trends
through the period with best chances across the mountains each day
until Saturday when the spread into the foothills as well. Highs and
lows will remain nearly steady above normal through the period.


At KCLT and elsewhere in the Piedmont: VFR at the TAF terminals,
though very early this morning a couple of more rural sites may see
brief vsby restrictions in fog, until drier air advects in closer
to dawn. Cold advective flow will promote mixing and gradient
remains sufficient to expect breezy/gusty conditions today. Winds
will prevail NW until this evening, when they will back a bit but
tend to go light/VRB. A few showers could develop over western NC
late this aftn but expected coverage is too sparse to mention in
TAFs at this point.

At KAVL: Moisture banking against the Appalachians will produce
low VFR cigs early this AM, which at times will lower to MVFR. A
TEMPO has been included accordingly.

Outlook: Mainly VFR conditions will prevail through early
week. Scattered afternoon SHRA/TSRA may return Wednesday, with
daily coverage increasing Thursday and Friday.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       Med   76%     High 100%     High 100%     High 100%
KHKY       High  92%     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 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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