Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 161847

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
247 PM EDT Sun Oct 16 2016

A low level ridge of high pressure will remain over the region, with
drier ridging building in aloft through at least the middle of the
week and temperatures rising to well above normal. Moisture and rain
chances will return by the end of the work week as a cold front
approaches the area.


As of 230 pm EDT Sunday: Overall really quiet through the near term
with upper high over Texas ridging toward the Southeast, with
corresponding surface high centered over the Carolinas. Some low-
level moisture remains in place from the remnants of the shortwave
that went through yesterday, plus southerly flow around the base of
the surface high has led to some weak upslope with increasing
cloudiness and a few sprinkles over the mountains. The Piedmont has
cleared out nicely with temperatures increasing to above seasonal
normals. As the upper ridge builds tonight and tomorrow, weak
subsidence aloft will clear out most of whatever clouds may be left
across the Piedmont, but continued (very weak) upslope may keep some
cloudiness in the mountains. Will probably see at least some patchy
fog tonight as high dewpoints will keep overnight lows several
degrees above seasonal normals.  This trend continues tomorrow as
thicknesses increase with the building upper ridge and low level WAA
continues around the surface high.


At 140 PM Sunday: Not much change needed to the going fcst. The
models continue to agree well wrt the high confidence ridging
pattern, which has progged little in the past 24 hrs. A strong ulvl
sub-trop ridge will continue to build east through the
period....while Atl sfc ridging remains in place. Model soundings
show a pronounced subs inversion developing with h8 temps
increasing to 12C-14C each afternoon. This will limit any sfc-based
convection to the development of fair wx Cu which will be more
likely across the srn zone in a relatively higher sw/ly moist layer.
There could be some brief and highly isol -shra/tstms across the
higher terrain late Wed afternoon...but besides that the main wx of
interest will be the above normal temps with maxes reaching around
10 degrees above normal each day. Mins will remain right around
normal in good cooling conds with no frost/freeze concerns across
the higher elevations.


At 230 PM Sunday...the medium range continues to give the models
some fits with how to handle the flow regime over the east and
southeast late in the week. The model guidance has started to show a
bit better run-to-run continuity. It now appears to be a question of
whether the main upper flow will feature a full latitude progressive
trof, or if a low will cut off in the srn stream. Think the
progressive full latitude trof has a better chance of working out
across our region and that scenario, similar to what is depicted by
the ECMWF, will be favored in the new fcst. This scenario also
follows the old rule about forecasting dry weather when in a
drought. If the new ECMWF is correct, a lot of people will be
disappointed because we will get just a quick shot of showers with
the cold front that would barely put a dent in rainfall deficits.
The low pressure system over the wrn Atlantic is a complicating
factor because it would tend to prevent much Gulf moisture from
moving nwd ahead of the cold front approaching from the west. The
model trend suggests cutting back on the time range that precip
chances are forecast, thus we dry out Friday night and thru the
weekend. It also suggests limiting precip probability to the chance
range. Temps should also cool down a bit faster with frontal passage
happening earlier and quicker, so min temps Friday night were
knocked down 5-10 degrees, but probably still too warm for much
frost potential over the NC mtns.


At KCLT and elsewhere: VFR this afternoon and evening with FEW-
SCT VFR Cu and light S/SSW winds (5kt or below). With little in the
way of cloudiness overnight, expect patchy MVFR fog to form at most
sites, though chances are too low to include at KCLT at this time.
For KAVL, most guidance is pointing to 1/4SM or less, but have kept
current trend of 1SM given trend of poor overnight vsby guidance.
Any fog/br should lift quickly Monday morning with continued lgt/vrb
or light S/SSW winds.

Outlook: Surface high pressure, drier profiles, and ridging aloft
will set up across the region through the middle of the week. The
potential for mountain valley fog and low stratus will continue each

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High  91%     High  97%
KAVL       High 100%     High 100%     High  95%     High  96%
KHKY       High 100%     High 100%     High  88%     High  91%
KGMU       High 100%     High 100%     High  94%     High 100%
KAND       High 100%     High 100%     High  97%     High  97%

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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