Area Forecast Discussion
Issued by NWS Greer, SC
FXUS62 KGSP 261852
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
252 PM EDT Wed Oct 26 2016
A weak and mostly dry cold front will cross the area Thursday. Warm
high pressure returns Friday before another weak frontal passage
occurs late Sunday. Warm and dry high pressure moves in early next
.NEAR TERM /THROUGH THURSDAY/...
As of 220 PM EDT: Satellite imagery shows a shortwave moving through
MO this afternoon, with convection trailing along an associated cold
front back through the southern plains. Meanwhile, surface high
pressure draped along the eastern seaboard will continue to migrate
offshore tonight as the approaching surface cold front crosses the
lower OH and mid MS river valleys. The upper wave is expected to
gradually dampen as it approaches the Appalachians overnight and
crosses the forecast area on Thursday. Upper level forcing will be
quite muted with the trough passage, and the surface front is
expected to only slowly lay over into the region late in the day.
The forecast area should thus remain dry overnight with just small
southwest NC mountain shower chances creeping in on upslope flow
after daybreak. The slightly deeper moisture along the frontal zone
will then spread across the mountains through the day but with just
scattered PoPs advertised. Forcing and moisture appear much less
east of the mountains Thursday afternoon and modest instability will
be relied upon to get much QPF at all. The instability looks quite
reserved in most areas, with SBCAPE possibly reaching 500 to 700
J/kg in the far SW mountains and also southeast of CLT late day. The
thunder potential is slight at best. Expect a milder night with
overnight mins in the 40s and lower 50s throughout as clouds
increase. Maxes should run about a category above climo with
pre-frontal warm advection Thursday.
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 2:30 pm EDT Wednesday: May feature for Thursday night through
Saturday is the passage of a frontal system Thursday night which
will mainly serve to shift the winds from southwesterly to
northwesterly. There is a slight chance for showers with the
passage of the front, but moisture in the atmosphere looks to still
be on the dry side, and the dynamical lift is not strong enough to
produce significant rainfall. Temperatures will not be much affected
either, with highs Friday and Saturday reaching the low 80s Friday
and Saturday in piedmont areas, though low temperatures will be a
little close to normal (though seasonally warm).
Following passage of the front Friday morning, POPs decline to
single digits through Saturday as broad, flat ridge over the
southeast CONUS replaces the frontal trough and keeps the boundary
layer dry and keeps shortwaves north and west of the area.
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
At 230 PM Tuesday: Medium range guidance indicates that low pressure
will track NE off the New England coast. An associated cold front is
forecast to slip south across the mid Atlantic. Sfc high pressure,
around 1025 mb, will become centered over the New England states by
Monday morning. At H5, a long wave trough will ripple across the
central and northern Atlantic. The passage of the trough will limit
the strength of the sfc high, reducing the ridging sw along the east
facing slopes of the Appalachians. Precip and cloud cover should
favor the region north of the forecast area. I will keep the
forecast from Sunday to Monday dry. Temperatures are forecast to
remain 10 to 15 degrees above normal.
On Tuesday, the center of a H5 590dm ridge is expected to build
across the deep south. Another dry cold front is forecast to slip
across the mid west. Warm and dry conditions will remain on Tuesday,
possibly a degree warmer than Monday. The mid level ridge will
expand across the southeast U.S. as sfc high ridges across the
western Carolinas. On Wednesday, dry wx with high ranging from the
mid 70s within the mtn valleys to near 80 east of the mtns.
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
At KCLT: Surface winds will gradually veer as high pressure migrates
off the eastern seaboard and a cold front approaches from the west.
High level cloudiness will gradually increase and thicken and some
model RH profiles hint at MVFR level clouds forming around daybreak.
This moisture return appears overdone and is not carried in the MOS
so will keep cigs VFR for now. No precipitation will be mentioned,
with just slight chances in the forecast after the 18Z cutoff.
Elsewhere: High level cloudiness will increase and lower through the
period, with lower VFR cumulus developing over the mountains and
foothills in warm advection Thursday morning. Expect light surface
winds to slowly turn more S then SW and increase slightly through
the period. Will only mention VCSH near the end of the TAF at KAVL
for now, with moisture and forcing expected to be too limited for a
mention across the foothills. Light fog in the SW NC mountain
valleys will be possible again, but not as dense given the
Outlook: A weak cold front will cross the area Thursday afternoon
and Thursday night, but with very limited moisture. Dry high
pressure will return Friday through the weekend and last into early
19-01Z 01-07Z 07-13Z 13-18Z
KCLT High 100% High 100% High 100% High 98%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% 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 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: