Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Greenville-Spartanburg SC
1050 am EDT Tuesday Oct 13 2015
a cold front will slowly cross the region today. Dry high pressure
will gradually build into the area from the west Wednesday through
Thursday. Another cold front will arrive from the northwest on
Near term /through tonight/...
as of 1040 am EDT...visible satellite imagery shows a few vestiges
of mountain fog in the lower valleys...but these areas should be
quick to scatter through the remainder of the morning. Although the
pre/frontal band of showers has moved well east of the region...the
approaching surface cold front remains west of the mountains and
will make slow but steady progess east across the area through late
day. Otherwise...expect low end gusts in the west-southwest flow this
afternoon...with maximum temperatures above normal given the full sun and
High pressure will slowly start to work into the area behind the
front tonight. There could be some northwest flow upslope moisture to
produce a few clouds...but no precipitation is expected in the northern
mountains. Gusts will likely continue along the higher peaks in the
weak cold advection...with lows near or slightly below normal.
Short term /Wednesday through Thursday night/...
at 230 am Tuesday...on Wednesday morning upper trough will extend
from Hudson by to the southern Appalachians...while an upper ridge
be along the West Coast. Shortwave energy rounding the trough will
cross our area early and late on Wednesday. The upper trough broadens
on Thursday...resulting in nearly zonal flow over the southeast...
and shortwave energy will pass north of our area on Thursday and
At the surface...on Wednesday a departing cold front will cross the
Gulf Stream and the northern Gulf of Mexico...while high pressure
crosses the plains and middle MS River Valley. Aside from some
lingering moisture over the northern NC mountains...our area will
experience drying in west flow behind the front. On Thursday the center
of the upper ridge reaches the southern Appalachians. Temperatures
will cool from near normal to below normal.
Long term /Friday through Monday/...
at 230 am Tuesday...on Friday morning a broad upper trough will be
over all but the westernmost portion of North America...with its
axis from Hudson Bay to the southern Appalachians...while an upper
ridge will be along the West Coast of Canada. The upper pattern
gradually progresses and deamplifies...such that by Monday the the
trough axis is over the western Atlantic...and the ridge axis is
over the Great Lakes and Gulf states. By Tuesday the ridge axis
reaches the East Coast...while an amplifying upper trough progresses
to from The Rockies to the plains.
At the surface...a cold front will cross our area from the northwest on
Friday...but with limited moisture...precipitation does not seem
likely at this time. On Saturday and Sunday high pressure moving
from the plains to the Ohio River valley builds east over the southern
Appalachians. The surface high reaches Virginia by Monday..extending over
most of the eastern Seaboard. Temperatures will cool to almost 10
degrees below normal.
Aviation /15z Tuesday through Saturday/...
at kclt...low level moisture behind the departed line of rain showers has
allowed MVFR ceilings to develop...but these should continue to scatter
out through the late morning hours...with mainly scattered VFR
cumulus for the afternoon. SW to west-southwest gusts will develop with
mixing...but expect maximum gusts to remain below 20 knots. Winds will
diminish and turn west-northwest this evening then light northerly overnight. Will
continue the VFR forecast for overnight...but guidance remains split
on any fog potential.
Elsewhere...kavl will continue to lift/scatter with heating and nearly
mixing into the French Broad valley. Otherwise...espect scattered
VFR cumulus around the region. Low end SW to west-southwest gusts are likely
across the foothills. Winds will turn more west-northwest to northwest this evening
and overnight...with gusts diminishing everywhere but the higher
peaks. Fog will be possible overnight...but will wait until the full
suite of 12z guidance arrives to assess any needed changes.
Outlook...dry and mainly VFR conditions should be seen into the
15-21z 21-03z 03-09z 09-12z
kclt high 100% high 100% high 100% high 100%
kgsp high 100% high 100% high 100% high 100%
kavl high 94% high 100% high 100% high 92%
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: (must be lower case)