Area Forecast Discussion
Issued by NWS Greer, SC
FXUS62 KGSP 270552
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
152 AM EDT Thu Oct 27 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 TODAY/...
As of 135 AM...not much happening across the western Carolinas apart
from thickening mid/high clouds streaming overhead. Upstream radars
show some light returns, but it seems unlikely that any precip will
reach the ground over the western zones before sunrise.
Otherwise...it appears most areas should see mins a little warmer
than normal. Mesoscale and short term model guidance continue to
hold any pre-frontal shower activity west of the Appalachians
through the overnight, so pops will be maintained at less than
Otherwise, 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 crosses the region 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 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. Maxes
should run about a category above climo with pre-frontal warm
.SHORT TERM /TONIGHT 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 WEDNESDAY/...
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 /06Z THURSDAY THROUGH MONDAY/...
At KCLT...VFR conditions are expected to persist for at least the
next 12 hours or so. There is some indication that a visibility
restriction could develop to the S and E of CLT, but the chances of
that developing at the airfield appear to low to mention. Expect a
light SE wind with thickening high and mid clouds through the early
morning hours. At some point around daybreak, the wind should come
around to SW and stay there for the rest of the period. Some lower
clouds will eventually arrive but the base should be above 050. The
operational models suggest a shower chance in the late afternoon,
but prefer to keep only a hint of this with a VCSH after 17Z. Even
if this does develop, in all likelihood it would not produce a
flight restriction. The actual cold front will be moving through
right around the end of the TAF period.
Elsewhere...will be watching for fog development in the mtn valleys,
which has limited potential because of high cloudiness and high
dewpt depressions at the current time. Included a TEMPO for some
MVFR visibility at KAVL but confidence is kind of low. The other
problem might be an MVFR-level cloud deck encroaching on the Upstate
of SC around daybreak. Some of the model guidance has this, so a
TEMPO or prevailing condition was included at KAND/KGMU/KGSP through
the late morning. Once that lifts, there could be an isolated shower
or patches of light rain, so a VCSH was thrown in. The best
chance...around 30 pct...will be at KAVL thru the afternoon hours.
The front will cross the mtns this evening, bringing the wind around
to NW by the end of the period at KAVL.
Outlook: Dry high pressure will build in behind the front Friday
through the weekend. The influence of the high will continue into
early next week with VFR conditions.
05-11Z 11-17Z 17-23Z 23-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 95% High 100%
KAVL High 100% High 83% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 95% High 100%
KAND High 100% High 100% Med 65% 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: