Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 162015

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
315 PM EST Sun Dec 16 2018

Drier air associated with broad high pressure will spread over
the region today and tomorrow and linger through midweek. Another
low pressure system is then expected to develop to our west and
bring widespread precipitation to the region for Thursday and


As of 245 PM EST Friday: Upper low continues to swirl just off
the Mid-Atlantic coast and push off to the northeast this
afternoon, as seen from latest satellite imagery, with NW flow
continuing to infiltrate into the western Carolinas behind the
exiting system. Across the NW Piedmont and Upstate SC,
conditions have remained fairly quiet today with plenty of
sunshine allowing for temperatures to climb above normal. As for
areas along the TN/NC border, a mix of cloud cover and isolated
light showers has prevailed with low level moisture lingering
over the TN and OH valleys and additional upslope forcing as a
weak upper SW continues to move overhead. As this available
moisture source decreases overnight, expect cloud cover and
isolated precipitation to decrease as well. Would not completely
rule out a few snowflakes mixed in, especially along the higher
ridges, though do not expect any snow accumulation. Overnight,
with clear skies outside the mountains and gradually clearing
skies along the TN/NC border, overnight low temperatures are
expected to dip into the 30s, remaining in the mid to upper 30s
across the NW Piedmont and Upstate. With residual saturated
soils, could not rule out patchy areas of fog towards morning.

Though lingering weak troughing looks to remain over the area on
Monday as upper ridge continues to build over the central US,
conditions are expected to remain dry and quiet with plenty of
sunshine, maybe some passing thin cirrus. Temperatures along and
south of the I-85 corridor will warm into the low 60s, back into the
upper 50s towards the escarpment, and slightly cooler across the


As of 140 PM EST Sunday: Quiet weather persists in to the short term
with weakening broad northwesterly flow aloft Tuesday transitioning
southwesterly well in advance of the late weeks system which will
begin organizing across the Southern Plains by Wednesday. Can`t rule
out some patchy fog under mostly clear skies Tuesday morning.
Otherwise, expect increasing mid to high level clouds as early as
Tuesday night, but more likely Wednesday. Seasonal temperatures are
expected through the period.


As of 315 PM EST Sunday: Model guidance is gradually coming into
better agreement with the storm system for late in the work week. A
strong 150+ mph jet streak is expected to dive down into the west
side of the trough over the southern plains Thursday as is continues
its trek towards the deep south. Increasing upper level divergence
aloft on the cyclonic side (east side) of the trough will fuel
fairly rapid intensification of the surface reflection of the
cyclone as it moves roughly along or just west of the Appalachians
into the eastern Great Lakes Thursday into Friday, before pressing
further into southeast Canada. The net result will be increasing and
lowering clouds across the forecast area early in the day on
Thursday before increasing south to southeasterly flow over weak
insitu damming brings increasing rain chances from south to north
Thursday afternoon and evening and continuing overnight. The latest
guidance indicates that a developing warm sector may push into the
region Thursday evening or night, scouring out any remaining insitu
damming. There are even signs that some thunderstorms may be severe
(low CAPE, high shear). However, this potential will be highly
dependent on the eventual track of the sfc low and erosion of any in-
situ damming in place. As a result of the uncertainty this far out,
have limited thunderstorms just before mentionable levels for now to
match surrounding offices. Developing northwest flow (gusty across
the mtns) on the back side of the system will likely bring continued
shower activity focused across the NC mountains near the TN border
Friday. Much uncertainty remains for this portion of the forecast,
although accumulating snowfall is possible, especially across higher
elevations. Things will dry out over the weekend with a return to
mostly sunny skies. Near to below normal temperatures are expected
Thursday through Saturday, possibly moderating to above normal,
especially east of the mountains Sunday as cold air advection
relaxes under mostly sunny skies.


At KCLT and elsewhere: Despite lingering cloud cover and isolated
drizzle/showers along the TN/NC border, VFR prevails at all TAF
sites this afternoon as intermittent thin cirrus pass overhead.
Expect conditions to remain quiet through the overnight hours,
though would not entirely rule out patchy MVFR fog towards daybreak,
especially across the Upstate and NW Piedmont, where soils remain
saturated. However, given low confidence, have not introduced into
going TAF fcst attm. With NW winds currently at KAVL, elsewhere,
winds will continue to veer from the SW to NW through this evening,
with sustained winds 5 to 10 kts. Given CAA, intermittent gusts,
especially at KAVL and KHKY are possible through this evening.

On Monday, expect VFR to prevail with SKC/FEW250 and WNW winds 5 to
8 kts.

Outlook: A wet low pressure system looks likely to bring
restrictions Thursday, perhaps lasting into Friday in some areas.
Otherwise, expect VFR.

Confidence Table...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
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 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:




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