Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 192112

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
512 PM EDT Wed Oct 19 2016

Dry and warm high pressure will continue through Thursday with maximum
temperatures once again flirting with record highs. A cold front
will cross the area Thursday night, increasing rain chances mainly
across the mountains. Drier and much cooler conditions will set up
across the area over the weekend. A dry front will push through from
the north late Monday and settle south of the region on Tuesday.


As of 500 PM EDT Wednesday: Made some minor tweaks to temperature
trends (since we`re still running a little on the warm side), but
other than that no changes for the early evening update. Otherwise,
deep layer ridging setting atop the southeast continues to dominate
the wx pattern, and will do so through the overnight hours into
Thursday.  As such, temperatures have surged into the mid/upper 80s
across portions of the cwfa, with the warmest levels residing over
the SC Upstate and northeast GA.  Meanwhile, a rather progressive H5
trof and associated surface cold front are pushing into/through the
plains states before continuing to move east into the lower/mid MS
river valley overnight.  By midday Thursday said front is fcst to
push into the TN valley while the persistent upper/sfc highs advect
east over the western Atlantic.  As such, flow will increase out of
the south setting up a modest prefrontal warm sector.  The front
itself won`t move into western NC until beyond the near term period,
however given the increasing lapse rates and much weaker subsidence
thanks to the falling heights aloft, did allow pops to increase late
in the period to slight/chance levels along the TN line. While the
best shear looks to remain westward through this fcst period, it
will be increasing and thus cannot rule out a few weak thunderstorms
into the late afternoon hours, especially given the improved thermal
profiles.  Temperatures on Thursday will once again be well above
normal levels, however should be a bit cooler than today given the
departing ridge axis and increased cu.


As of 305 PM EDT Wednesday: Guidance remains in good agreement
regarding the short tern. A strong short wave approaches the area
Thursday night and crosses the area Friday. A weak trailing short
wave moves through the developing upper trough and across the area
Saturday. The associated surface cold front moves into the area
Thursday night and across the area Friday. Expect an increase in
precip chances from west to east Thursday night with chances falling
on Friday. Best chance will be across the NC Mountains and I-40
corridor where moisture is highest. There is still little in the way
of low level moisture inflow with weak SW low level flow ahead of
the front. This also results in little to no instability even with
the strong short wave as mid level temps don`t show much cooling.
There is quite a bit of bulk shear, however it is behind the front
where there is even less instability. This should limit any severe
weather potential. QPF values will also generally be light with the
fast moving system and limited inflow.

Windy conditions will develop Friday as strong winds move in behind
the front and mixing develops tapping into the stronger winds. That
said, there is little to no low level 50 knot winds. Cannot rule out
the need for a high elevation wind advisory. Breezy to windy
conditions will linger though Saturday with slowly diminishing
winds. Some lingering NW flow precip will remain across the
mountains late Friday into Friday night. Cannot rule out some
flurries across the highest elevations Friday night as H85 temps
fall below freezing. Morning winds should preclude much of any
frost, and only the highest mountain ridges should see an advective
freeze Friday night.


As of 230 PM EDT Wednesday...A large and broad upper ridge will
build in across the middle of the CONUS, as a deep trough exits off
the East Coast Saturday night thru Sunday. A surface high will slide
southeast into the region, roughly centered over the CWFA by 12z
Sunday. With heights rising aloft, the mountains may not be as cold
as Friday night, but the valleys and piedmont should see the coldest
night behind the front Saturday night, with lows in the upper 30s to
mid 40s. Some patchy frost will be possible, especially in the
sheltered Little TN Valley.

Monday into Tuesday, a fast-moving upper trough will cross the Great
Lakes and dig as it reaches the Eastern Seaboard. This will allow a
dry cold front to slide south across the area late Monday. So while
temps rebound Sunday and Monday, the front should bring temps back
down to near normal for Tuesday. Skies should be clear or mostly
clear thru the medium range.

Wednesday, the surface high should gradually slide east across the
Mid-Atlantic and Northeast states. So return flow out of the east or
south will bring slightly above normal temps and some increase in


At KCLT and Elsewhere: No changes to the KCLT TAF for the 21z AMD.
VFR to prevail at all sites outside of the mtns through the period
as deep layer ridging dominates. Light/moderate south to southwest
flow is expected beneath a few low cu this afternoon.  Expecting any
low clouds to erode into the late afternoon/evening hours as winds
calm.  Guidance continues to hint at high mvfr visb issues at
KCLT/KHKY, however didn`t have enough confidence to lower said sites
to those levels. Furthermore, guidance still favors ifr at KAVL by
way of mtn valley fog near daybreak, however once again am skeptical
given dry llvs and the possibility of increased low vfr stratus
across the mtns. As a trof/front approaching from the west am
expecting the surface ridge to weaken on Thursday allowing for
faster cu development thus did include in all tafs by 15z.  Winds on
Thursday should remain light and out of the south/southwest.

Outlook: A front will approach the region Thursday night moving
through the area on Friday, bringing a period of gusty winds and
perhaps restrictions due to cloud cover.  Cool/dry high pressure
returns for the weekend keeping chances for restrictions low.

Confidence Table...

            21-03z        03-09Z        09-15Z        15-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High  98%     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:



  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      83 1938     47 1891     61 1910     27 1976
   KCLT      87 1938     55 1976     66 1937     30 2009
   KGSP      87 1941     56 1976     65 2006     32 2009


  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      83 1985     42 1961     62 1950     25 1981
   KCLT      86 1926     49 1989     66 1993     30 1972
   KGSP      86 1899     50 1989     68 1894     29 1972




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