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fxus62 kgsp 291108 

Area forecast discussion
National Weather Service Greenville-Spartanburg SC
708 am EDT Wed Mar 29 2017

dry high pressure will build south from eastern Canada along the
East Coast today. Moisture will gradually return on Thursday, with
abundant moisture in place by Friday as a strong low pressure system
moves east from the Mississippi River valley. Drier weather will
return for the weekend with unsettled weather returning early next


Near term /through tonight/...
as of 650 am edt: morning fog has been hit a bit harder in the
southwest mountain valleys this morning. Otherwise, the forecast
remains on track with the departing surface cold front continuing to
settle southward across central Georgia and extreme southern SC
today as sprawling surface high pressure builds down from the
eastern Great Lakes. Meanwhile, a vigorous closed low pressure
system over the Southern Plains will deepen today and enhance
downstream ridging over the southeastern U.S. Good insolation and
only limited thickness falls behind the front in our area will
permit temperatures to once again reach into the lower 80s in much
of the foothills and Piedmont across northeast Georgia and upstate SC,
with plenty of 70s elsewhere.

Under continued ridging aloft, 850 mb moisture will begin pooling
east of the Blue Ridge late today, and southerly upglide forcing and
moisture will develop tonight over the surface ridge. This will
permit light rain or drizzle to begin breaking out, especialy over
western NC east of the Blue Ridge. This will Herald the onset of
cold air damming conditions by daybreak Thursday.


Short term /Thursday through Friday night/...
as of 230 am EDT wednesday: a moist wedge will continue to build in
across forecast area early Thu. Models show good moist flow persisting off the
atl thru the day atop the cold dome which will instigate showers rather
quickly across the nrn wedge front which will expand across most
zones thru the afternoon. Qpf amounts will be light with the higher
amounts aligned mainly along and southeast of the br. There will
likely be some differential heating along the srn periphery of The
Wedge front where general tstms are possible. The better instability
shud remain southeast of this area. Max temps will vary widely
across the area with the nrn zones hitting arnd 60 and mid 70s
realized across the srn zones. With good cloud cover and continued
precip...low temps will only drop off 10-12 degrees.

The Fri period still looks interesting beginning early on. A strong
dynamical system will approach from the west and begin to break down
The Wedge aft 06z likely creating a retreating tmb scenario. Bulk
shear will increase to arnd 50 kts along the srn end of the bndry
while MUCAPE values increase to near moderate levels while mlvl
lapse rates steepen to near 7 c/km. BUFKIT soundings show very good
0-1 km helicity near the sfc bndry as rotating updrafts
will be possible. Thus...will keep with the previous trends and fcst
tstms early on...some of which could become stg/svr before daybreak
across the srn zones. Strong convec activity will likely continue
into the early afternoon while developing east and north. There is a
little concern with the deep h5 trof advancing a well defined S/W
across the nrn gom and perhaps producing moisture robbing
convec...yet there shud be enuf large scale forcing and residual
llvl atl moisture to produce and maintain convec south of the tmb
ahead of an incoming cold front. The cold front looks to cross east
of the area by the middle of the afternoon...clearing convec
activity as upslope -shra lingers across the mtn spine on the back
side of the sfc low. Will keep the same severe mention in the severe weather potential statement as
far as timing and areas affected.


Long term /Saturday through Tuesday/...
as of 315 am EDT wednesday: not much change from the previous fcst.
The models continue to show good agreement with small scale h5 Ridge
Crossing the southeast Continental U.S. Over the weekend. This will bring dry conds as
a sfc high builds across the mid-atl region. Good insol and NW/ly
downslope flow will enable Max temps Sat to reach a Cat or so above
normal. Winds will shift se/ly sun and good insol will again allow
Max temps similar to Sat/S highs. Both days will be rather pleasant
as dewpoints remain in the u40s.

Another storm system will affect the area Mon thru Tue. There
doesn't look to be too much precip coverage during the day Mon with
mainly mech lift -shra...but the overnight will see a warm front
cross to the north. There shudn/T be too much instability due to the
nocturnal timing...but soundings indicate MUCAPE of arnd 700 j/kg
early Tue thru mid morning. Combined with good deep layered
shear...this period could be under the gun for stg to svr tstms.
A dry slot will likely push in from the SW quickly limiting more
stable precip across the upslope regions and perhaps lingering tstms
across the northwest Piedmont thru 21z. Max temps Mon should be right arnd
normal or a couple degrees above with highs warmer by a Cat on Tue
in developing SW/ly flow.


Aviation /11z Wednesday through Sunday/...
kclt and elsewhere, surface high pressure will continue to build
down across the forecast area from the north today and persist
through tonight. Expect generally NE winds east of the mountains,
but with continued northwest upvalley flow at kavl through the morning
hours. Winds will gradually come around to a southeasterly direction
throughout by midday, and few to scattered VFR clouds will start to form
as 850 mb moisture begins pooling east of the Blue Ridge. The main
concern for restrictions early will be tempo IFR low clouds and LIFR
fog in the central and Southern Mountain valleys - including near
kavl. Otherwise, VFR cigs will develop tonight as upglide forcing
and moisture improve, with lowering MVFR restrictions developing
from 06z to 12z, and light rain or drizzle possible from kavl to

Outlook: moisture returning above a developing cool surface wedge
should result in low clouds and light rain across the area on
Thursday. The approach of a strong storm system will bring continued
chances of restrictions as well as a potential for heavy rain
showers and thunderstorms Thursday night and Friday. Drier
conditions will return again for the weekend.

Confidence table...

11-17z 17-23z 23-05z 05-06z
kclt high 100% high 100% high 100% high 94%
kgsp high 100% high 100% high 100% high 100%
kavl high 100% high 100% high 100% Med 69%
khky high 100% high 100% high 100% high 81%
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:



Gsp watches/warnings/advisories...



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