Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 272208

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
608 PM EDT Thu Apr 27 2017

Warm and humid high pressure will build in through the end of the
work week. A front will move into the area late this weekend,
increasing chances for showers and thunderstorms on Sunday. Another
front will approach by the middle of next week.


As of 6 pm EDT Thursday: Broken line of thunderstorms will evolve
into the foothills and piedmont this evening with best chances for
isolated svr storms within the lingering 1000-1500 j/kg sbcape field
acrs the piedmont where effective deep layer shear remains 40 to 50
kts. Primary sfc cold front will make only gradual progress
southeastward across the CWA and largely dissipate Friday afternoon
with little in the way of dry or cold advection in it`s wake.
Midlevel ridging also builds in on Friday as Central CONUS trough
digs more into the Southwest. Consequently, Friday`s temperatures
will warm into the 80s with more sensible humidity than we have seen
in recent months. Wet ground and any new precipitation along with
elevated dewpoints will give a good chance for fog Friday morning at
some level, especially in sheltered areas with reduced wind.


As of 225 PM Thursday: the short term fcst picks up at 00z on
Saturday with steep upper ridging building over the region as an
equally steep upper trof digs down across the extreme SW CONUS. The
upper ridge is expected to slowly drift eastward thru the period,
yet it should remain largely in place over our region. At the sfc,
the Bermuda High will keep warm southerly flow over the region thru
the period with the next frontal system approaching the fcst area by
the end of the short term late Sunday. The sensible fcst will be
marked by well above normal temps and high dewpts in the 60s. Better
cloud cover on Sun should keep temps about a category cooler than
Sat. These conditions should provide ample instability each day for
diurnally driven tsra.


As of 235 PM EDT Thursday...the extended fcst picks up at 00z on
Monday with steep upper ridging centered just off the Atlantic Coast
and a deep upper trof moving across the Southern Plains and into the
Mississippi River Valley. As the trof approaches our area, it is
expected to lift NE and up over the Great Lakes by early Tuesday.
Over the next 24 hrs or so, the trof lifts farther NE over southern
Ontario/Quebec as heights begin to recover over the southeast.
During the remainder of the period, a southern stream upper trof
amplifies over the ArkLaTex region and encroaches upon our fcst area
by the end of the period late Thursday. At the sfc, warm sly flow
will persist across the area into early Monday. The next frontal
system will move thru the fcst area sometime Monday morning to
Monday afternoon bringing with it a good chance for widespread
showers and ts. Drying high pressure will overspread the area in the
front`s wake on Tues with another frontal system approaching the
CWFA by the end of the period on Thurs.


At KCLT and elsewhere:  Main issue will be progress of a round of
thunderstorms this afternoon and evening.  Progress of system and
approach of front from the west has reduced CIGs to as low as 20kft
in areas without precip., and down below 10kft in areas with.
Current widely scattered showers will give way to some -TSRA this afternoon
with the heaviest activity expected from 20Z to 24Z and lingering
scattered showers after that.  Front with this system is quite weak,
and winds outside of areas with convection will be weak, with light
and variable winds on Friday.  Continued moist low-levels is
expected to lead to fog in the morning, especially in areas with
less wind.

Outlook: High pressure on Friday should lead to widespread VFR with
more diurnally-based showers and thunderstorms possible Saturday and

Confidence Table...

            22-04Z        04-10Z        10-16Z        16-18Z
KCLT       High 100%     Med   62%     Low   55%     High  84%
KGSP       High  80%     Low   57%     Med   66%     High  80%
KAVL       Med   71%     High 100%     High  90%     High 100%
KHKY       Med   69%     Low   53%     Med   76%     High  90%
KGMU       Med   67%     Low   55%     Med   77%     High  80%
KAND       Med   60%     Low   57%     Low   53%     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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