Area Forecast Discussion
Issued by NWS Greer, SC

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712
FXUS62 KGSP 162257
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
657 PM EDT Mon Oct 16 2017

.SYNOPSIS...
In the wake of a cold frontal passage, dry conditions and below-
normal temperatures will persist through mid-week. Warmer
temperatures will return later this week as deep-layer ridging sets
up over the Southeast US.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 650 PM EDT Monday:  Updated discussion for 00z taf issuance.
Skies continue to clear out in the wake of the front as caa
prevails.  Temperatures this hour across the region have lowered
into the 50s/60s which seems a bit chilly given the modest nly
flow, with dewpoints falling into the 30s/40s.  All in all no sig
changes were needed/made to the fcst with this update.

As of 230 PM EDT Monday: Deep upper trough will dominate the area
this afternoon and evening in the wake of this morning`s cold
frontal passage. Some lingering clouds are hanging on across our
extreme southeastern zones, along with some NW flow Cu working
across the middle and northern mountains and some passing high
clouds. Cool surface high pressure over the center of the country
will slide east today and toward the OH Valley, but the gradient
across our area will only gradually weaken; certainly not enough
to allow winds to go calm tonight, and may still see some brief
low-end gusts during the day on Tuesday. More noticeable, however,
especially for anyone outside today, is the absolutely beautiful
conditions this front has left for us. Dewpoints have been
decreasing across the area through the day and deep-layer CAA will
really be felt tonight, with lows 15 to almost 20 degrees cooler
than what we saw this morning, and actually a good 5 or so degree
below seasonal normals (really, just plain normal would have been
fine). As for frost potential, continued trend of leaning toward
bias-corrected values for overnight lows, and while the mountains
and nearby valleys will be dropping to the mid 30s (and in some
cases flirting with freezing), looks like in general winds will
be too strong to support much in the way of frost except for in
the most sheltered of areas. Cannot rule out some patchy frost in
these areas, but without winds dropping more, just not supportive
of enough frost to warrant an advisory at this time.

The upper trough will lift and push east during the day tomorrow,
but the high pressure will begin to settle overhead, so while
the weakening CAA will allow mountain sites to warm up tomorrow,
the Piedmont will drop a few degrees cooler tomorrow than today
(and generally also 5 or so degrees below climo), aided in part by
winds shifting around to the NE rather than N (which, especially
across the western half of the Upstate, brings with it a downsloping
component). Mostly clear skies and still a bit of a breeze will
result in a pleasant, albeit somewhat cool day.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 150 PM EDT Monday: Ridging to provide clear skies along with a
light northerly sfc flow to promote a chilly Tuesday night. Daybreak
Wednesday minimum temperatures pretty close to the inherited fcst, a
blend of the milder MAV and colder MET numbers and leading to frost
potential for the Mtn valleys, NC foothills and a good chunk of the
Carolina Piedmont.  With abundant sunshine expected for Wednesday
and Thursday along with some developing weak return flow, will plan
on fcst max temperatures rebounding close to climo on Wed and a bit
above normal on Thursday.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 130 PM EDT: A 580 dm 500 mb ridge axis will build over the
southern Appalachians Friday before migrating over the southeast
coastline on Saturday. Very dry profiles will continue in place over
the forecast area under the associated surface high and broad ridge
aloft, with temperatures rebounding to well above climatological
values.

A full latitude trough will amplify over the central CONUS on
Sunday, before the southern stream cuts off somewhere over, or west
of, the lower Mississippi river valley. Meanwhile, low-level
Atlantic moisture, and mid and upper level moisture in the
developing deep layer southwesterly flow, will start returning to
the southeast late Sunday into Monday as the parent surface high
slips offshore. PoPs will ramp up into the chance range for showers
ahead of the southern tier system and a smaller diurnal range on
temperatures will set up with a possible hybrid or in-situ weak
wedge developing.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and Elsewhere: VFR conditions will prevail through
the period at all sites.  Few high cirrus will erode into the
overnight leading to skc for the rest of the period.  Winds will
remain somewhat elevated overnight as the PG is enhanced, thus
all sites feature 6-10kt nly flow with perhaps a brief period of
gusting by late morning, calming into the afternoon.  All in all
a rather nice taf cycle.

Outlook: Seasonably cool and overall VFR conditions will persist
through the work 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%     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:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...CSH
NEAR TERM...CDG/TDP
SHORT TERM...CSH
LONG TERM...HG
AVIATION...CDG



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