Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 010220

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1020 PM EDT Fri Sep 30 2016

Dry southwest flow will linger across the region through this
weekend. Progressively warmer temperatures are on tap through early
next week. The path of tropical cyclone Matthew will be closely
watched as it tracks north near the Atlantic coast next week.


As of 1020 PM EDT, a deep closed low pressure system over the OH
Valley will keep a strong upper jetlet over the Appalachians tonight
before it lifts northeast through Saturday. Any associated upper
divergence will remain north and east of the area. However, there
will be a few clouds across the mountains. Cannot rule out some
patchy mountain valley fog despite the dry conditions. Meanwhile,
abundant dry air will continue to wrap into our region on the SE
side of the closed low. This will lead to good radiating conditions
tonight and yield min temps below climatology. Dry weather will
persist on Saturday as a weak surface trough lingers along the Blue
Ridge. Thicknesses will rebound slightly and full sun will raise
maxes about a category above climo Saturday afternoon.


At 200 PM Friday: On Saturday evening an anomalous closed upper low
will be centered north of the OH River Valley, with associated low
pressure extending outward to the Great Lakes, much of the East
Coast,a and the Gulf Coast. This low drifts toward New England early
next week. Meanwhile, low amplitude high pressure crosses the MS
River Valley, with nearly zonal upper level flow extending across
the Southeast.

At the surface, on Saturday evening a deep surface low will be
centered near the border of MI, IN and OH, while a weakening cold
front reaming off the east coast. Dry air between these two features
will extend from the Gulf Coast to at least VA. Modest moisture
spreads over our area from the west by Monday as the surface low
moves toward New England. The models show instability increasing
over the Southern Appalachians by Monday, but perhaps not enough to
supporting convection if a warn nose aloft can persist. Temperatures
will warm from near normal to slightly above normal as heights rise
aloft in the wake of the departing surface low.


As of 145 PM Friday: No changes needed to the inherited dry and warm
fcst to start off the period underneath the weak flow regime aloft.
Max temperatures Tuesday are slated to be just a few deg F less warm
than persistence within the tightening easterly flow between TC
Matthew and moderately strong sfc hipres center over New England.
The effectively dry fcst should continue through Wednesday, although
it should be a little less warm given the tightening northeasterly
sfc pressure gradient. During the latter half of the workweek, TC
Matthew remains progged to trek northward within the offshore
Atlantic waters. Mainly dry persistance fcst on tap for Thursday
within the continued NE llvl flow. On Friday, mid-conus upper trough
should be able to make some eastward progress with attendant but
weakening cold front possibly ringing out some showers across the NC
mtns, but we`ll see. At any rate, it could easily remain dry for
another day, and max temperatures will remain above normal.


At KCLT and elsewhere, drier air has fully covered the region and
will continue through the TAF period. Expect mainly VFR conditions
to  persist throughout the TAF period as well. The only location of
concern is KAVL in the French Broad River Valley where LAMP guidance
produces low restrictions in fog overnight. However, this does not
appear to be supported by the low crossover temperatures indicated
by lower 40s dewpoints that occurred during the afternoon. Expect
mainly light S to SW winds east of the mountains and more variable
flow in the mountain valleys dominated by up valley and down valley

Outlook: VFR conditions are expected in most places through early
next week as dry high pressure settles in over the area.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High  95%     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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