Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 160608

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
208 AM EDT Mon Oct 16 2017

Light rainfall chances peak this morning as a fast-moving cold
front moves through the area.  Dry conditions and below-normal
temperatures will follow the front beginning this afternoon, and
persist through mid-week.  Warmer temperatures will return later
this week as deep-layer ridging sets up over the Southeast US.


As of 200 AM Mon: Wind shift line of incoming cold front as crossed
the Appalachians, with scattered showers over the NW half of the
CWFA. A more contiguous area of precip is seen over the East TN
foothills attm, but guidance is split on how much downsloping will
affect this as it advects east over the next 2-3 hrs. Short-term
progs of MUCAPE reflect slight destabilization downstream of the
mtns over that same timeframe, so an uptick in shower coverage is
expected before daybreak over the Upstate and NW NC Piedmont as the
wind shift works in there. Consensus still depicts the postfrontal
moisture exiting the CWFA to the southeast by early afternoon.

Based upon the orientation of the post-frontal surface high, winds
are expected to shift to the N or even N/NE rather quickly in the
wake of the front this morning. This will preclude the amount of
substantial downslope warming that one would typically associate
with autumn fropas. Thus, even areas east of the mountains will
probably see maxes reached before or near noon, with temps remaining
steady through the day. The result will be forecast maxes around
5 degrees below climo this afternoon.


As of 2pm EDT Sunday:  By Monday evening, cold front and
precipitation will be well past the area to the southeast with dry
air advection on-going. Winds on Monday will be somewhat brisk out
of the north and will feel cold. By Tuesday morning, dewpoints
plummet nearly 20 degrees into the low-30s in the higher elevations
to upper 40s in the piedmont, and PWATS plummet to .4 inches.
Clouds also become scarce Tues. and Wed.  Following passage of upper
synoptic wave Monday night, region goes into a weakly forced regime
that is not much affected by passage of clipper-system through the
Great lakes on Wednesday.

Main issue Tuesday and Wednesday will be low temperatures in the
mornings which could give some patchy frost to the higher elevations.
Calm winds, clear skies, and dry air all combine for lows Tuesday
and Wednesday mornings that are several degrees below normal, and
well below the past few weeks.  Highs Tuesday and Wednesday are
anticipated to be near normal, which will be a substantial change.


As of 200 PM EDT Sunday: A southern stream wave will move off the
southeast U.S. coast Wednesday night, with a ridge building from the
MS River Valley to the southern Appalachians Thursday through
Friday. Surface high pressure will set up under the upper ridge
axis, with very dry profiles in place. The dominant ridge will
remain in place over the southeast for the first half of the weekend
before breaking down from the northwest on Sunday in response to a
full latitude trough sweeping east through the plains. Slightly
better low level moisture return from the Atlantic, along with
deeper layer SW flow aloft, should just be getting started at the
end of the forecast period Sunday night. Will feature a gradual
increase in clouds on Sunday, but the forecast will remain dry.
Temperatures will steadily rebound to about two to three categories
above climatological values through the long term period.


At KCLT and Elsewhere: A cold front will push through all terminals
this morning. Wind shift to NW has already occurred at KAVL and
will progress NW-SE across the area, happening at KCLT last, around
daybreak. Showers will accompany the front, with occasional MVFR
cigs and vsby. Though a wide band of VFR to MVFR stratus is present
behind the wind shift line over KY/TN, downsloping is expected to
keep this somewhat at bay, so TAFs reflect fairly rapid improvement
to VFR following end of showers. Some gustiness will occur today
as colder air filters in, particularly at KAVL. Clear skies and
NW to N breezes tonight; frost formation is a possibility at KAVL
and other mtn valley locations.

Outlook: Seasonably cool, dry, and overall VFR conditions will
persist through the work week.

Confidence Table...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       Med   76%     High  83%     High 100%     High 100%
KGSP       High  81%     High 100%     High 100%     High 100%
KAVL       Med   70%     High  83%     High 100%     High 100%
KHKY       High  82%     High 100%     High 100%     High 100%
KGMU       High  90%     High 100%     High 100%     High 100%
KAND       High  86%     High  83%     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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