Area Forecast Discussion
Issued by NWS Greer, SC
FXUS62 KGSP 301811
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
111 PM EST Wed Nov 30 2016
Cloudy conditions remain over the area today, along with scattered
showers mainly near the mountains, in the moist flow ahead of an
approaching cold front. That front moves thru this afternoon and
evening bringing precipitation chances across the region. Dry high
pressure fills in tonight after it moves out, persisting through
Saturday. Moisture will return Sunday into Monday ahead of another
developing low pressure system to the west.
.NEAR TERM /THROUGH TONIGHT/...
At 2 PM Wednesday: An upper trough will broaden and extend across
the Southern Appalachians overnight, with zonal flow resulting across
the southern tier of the USA resulting by Thursday. A weakening vort
lobe will pass cross the Central Appalachians overnight.
At the surface, a cold front will approach from the west this
afternoon, preceded by moist inflow from the Gulf of Mexico. Upslope
flow and modest isentropic upglide over the southern appalachians
will support moderate rainfall amounts, but the expected
acceleration of the front should preclude excessive rainfall.
Although instability is somewhat limited, enough shear will be
present to prevent completely excluding the chance of severe weather
across the area. The front should clear our area by late tonight,
followed by winds veering from south to northwest, and drier air
moving and clearer skies moving in. Minimum temperatures tonight
will run above normal. Maximum temperatures on Thursday will run
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
As of Noon EST Wednesday: Zonal flow will be in place aloft across
the eastern CONUS Thursday night through Friday. Meanwhile, shallow
NW flow moisture may persist along the TN border in the northern
mountains into Friday, but will carry no PoPs given the weak WNW
upslope character and very shallow moisture. Cold temperatures would
support flurries or snow, however, if more moisture arrives than
progged. Otherwise, surface high pressure will gradually build east
toward the Appalachian chain and keep profiles dry across the region.
A broad but shallow ridge will then develop through Saturday across
the southeast. Although model differences persist with the expected
upstream low pressure development across TX and the western gulf
coast, there is good agreement on little if any upglide moisture
returning through 00Z Sunday. Will thus keep the forecast dry
through Saturday afternoon. Temperatures Friday through Saturday
will be near to just below climo, slightly cooler Saturday than
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
As of 225 AM EST Wednesday: the medium range fcst picks up at 12z on
Saturday with flat upper ridging in place over the southeast and a
large H5 low cutting off from the southern stream flow over the Baja
Peninsula. Overall, the long range models appear to be coming into
much better agreement wrt the large scale pattern evolution. The flat
upper ridging is expected to remain in place over the region into early
next week as the closed low eventually becomes absorbed by the mean
flow to its north. By Monday afternoon, heights begin to increase again
as stronger ridging overspreads the region from the west.
At the sfc, the pattern evolution still appears more uncertain compared
to the upper levels. High pressure will be in place over the region to
start the period. As we move into Sunday and then early next week, the
sfc pattern becomes more muddled. The models try to develop some sort
of coastal low over the Gulf of Mexico, but it remains unclear exactly
where and when it will take shape. All of the models have a broad area
of deep moisture moving into the CWFA on Sunday from the west. The models
dry things out by late Monday as a central CONUS high moves over the fcst
area from the west. Over the next 24 to 36 hrs, the models move the high
up over New England and a CAD regime appears to setup by the end of the
period. I kept likely POPs on Sunday and then tapered them back to solid
chance for Monday and Tuesday. The temperature fcst is especially tricky
and could change quite a bit over the next few days as confidence in the
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: Model guidance supports rain induced
afternoon vsby restrictions at Foothill sites and KAVL as a cold
front moves across the area, but keeps KCLT VFR. Convection is
possible at all sites. As the front moves through overnight, winds
veer from south to northwest in NC, and west in SC, remaining just
strong enough to keep daybreak vsby restrictions from occurring. IFR
vsby restrictions this afternoon will lift to low VFR this evening
before eroding completely overnight.
Outlook: Dry high pressure returns in the wake of the front for
Thursday thru Saturday.
18-24Z 00-06Z 06-12Z 12-18Z
KCLT High 88% High 94% High 100% High 100%
KGSP Med 74% High 96% High 100% High 100%
KAVL Med 72% High 95% High 100% High 100%
KHKY Med 78% High 87% High 100% High 100%
KGMU Med 72% High 96% High 100% High 100%
KAND High 80% High 97% 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:
NC...Wind Advisory until 7 PM EST this evening for NCZ033-048>053-