Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 221737

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
137 PM 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 135 pm...The current forecast remains on track. Based on
recent CAMs...I expect weak showers to develop across the I-77
corridor over the next one to two hours. Little change will be made
within the near term of the forecast.

As of 1030 AM...latest W/V images indicate the core of a mid level
closed low sinking southward across the mid Atlantic states. As the
low approaches the western Carolinas this afternoon...lapse rates
will gradually steepen across the foothills and Piedmont. CAMs agree
that weak showers will develop this afternoon...mainly over the
upper I-77 corridor and western slopes of the nrn NC mtns. I will
update the forecast to spread schc PoPs west into the eastern
foothills. Otherwise...the current forecast appears on track.

As of 635 AM: An upper trough will deepen over the Eastern
Seaboard thru tonight. On the upstream side of this trough,
plentiful low level moisture and upsloping flow along the TN/NC
border are generating a layer of low clouds and a few very light
showers. 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,
and subsidence will increase as a vort lobe moves east of the area.

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...VFR. The center of a mid level low will
continue to drift southward through the evening hours. During the
remainder of the daylight hours...gusty NNW will remain across the
western Carolina terminals. Moisture and weak forcing associated
with the low may support a few weak showers...passing near KHKY and
KCLT through 23z. Wind gusts and showers should dissipate during the
early evening hours. On Monday...weak pressure fields will support
only light north winds. Conditions across the terminals should
remain dry.

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

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
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 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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