Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Greenville-Spartanburg SC
333 am EDT Thursday Oct 23 2014
dry high pressure will remain in control of the weather through
early next week.
Near term /through tonight/...
as of 230 am EDT...strong Canadian hipres will continue building
into the region today supported by short wave ridging and subs aloft. This
will create dry conds through the column with precipitable waters ranging from
0.25 to 0.35 west/east during maximum heating. Clouds will be hard to
come by once again tday with increasing cirrus by late afternoon from
the west ahead of an ulvl trough. The surface p/gradient will loosen over the
area as well with winds remaining in a weak northwest/ly config throughout
the day. Early to middle morning gusts across the mountain valleys will
relax in the afternoon as the bl loses momentum energy. Maximum temperatures
will be close to normal...likely a couple degrees below a low level
thickness trough slowly modifies in good insol.
The overnight will feature the advance of an 500 mb short wave trough. This trough
will be limited in moisture and only bring ulvl clouds through
daybreak. The latest NAM and GFS soundings account for these
clouds...but still develop weak to moderate surface/based inversion
across the County warning forecast area. Surface dew point/S will be too low for much of a visibility
concern...but dew point/S near freezing will make areas of frost probable
across all the NC mountains a Fr.Y will be issued for the NC mountain
counties not already turned off for the season by the earlier Oct
5th freeze. Mins will range from the lower to upper 30s across the
mountains and fthills...to the lower 40s non/mtns.
Short term /Friday through Saturday night/...
as of 315 am Thursday...classic autumn weather will continue
into the early part of the weekend...as another short wave dives out
of the Midwest to reinforce the mean trough over the eastern states.
This wave may bring a brief period of middle/high clouds on
Friday...and the remotest of mountain shower chances...but overall
the impact on sensible weather will be minimal. By Sunday...heights
will begin to rise in response to a building ridge over the central
Continental U.S.. therefore...while temperatures will begin the period very close to
climatology...maximum temperatures Sunday are expected to creep a category or so
Long term /Sunday through Wednesday/...
as of 255 PM Wednesday...guidance in good agreement indicating a pattern
change during the medium range...with the eastern trough being
replaced with a ridge through Tuesday. Southwesterly flow aloft develops Wednesday as
the ridge axis moves east and a trough moves into the central Continental U.S..
a dry front crosses the area Sunday with high pressure building in
Monday and sliding across the area Tuesday. The guidance differs on the
strength and speed of the trough...with the GFS weaker and faster
and the European model (ecmwf) stronger and slower. This results in the GFS
bringing a weak front into the mountains late Wednesday...and the European model (ecmwf)
bringing a stronger front with good southerly flow into the western County warning forecast area by
that time. For now...have limited pop to slight chance for the NC mountains
and northern tier...in line with a model blend...given the uncertainty.
Mild temperatures sun see a brief cool down Monday...then show a warming
slow warming trend through the end of the period.
Aviation /08z Thursday through Monday/...
at kclt and elsewhere...VFR flight conds through the taf period. High
pressure will continue to build across the region with supporting
ridging/subs aloft. This will create very dry profiles...with kavl
and khky possibly seeing few low clouds overnight. Frost development
is possible after 06z through 13z at kavl and khky as well. Weak winds
will remain aligned up valley at kavl and generally north-northwest/ly at all
other terminals except kand...where flow around the terrain will make
for west/ly flow in the afternoon. Upper clouds will begin to move in
from the west late in the taf period.
Outlook...quiet weather will continue across the region...as deep
layer ridging settles in through this weekend.
Georgia...frost advisory until 9 am EDT this morning for gaz010-017.
NC...frost advisory until 9 am EDT this morning for ncz063.