Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 221817

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
217 PM EDT Thu Jun 22 2017

The remnants of Cindy will move northeast into southern Arkansas
tonight while widespread tropical showers impact our region through
Friday morning.  Shower coverage decreases briefly Friday morning
before a cold front approaches the mountains later in the day.
Showers and storms return Friday afternoon and evening as the cold
front slides into the region.  Light showers linger on Saturday as
the front slowly departs the area, but unseasonably cool and dry
weather follows the front and will persist through next Thursday.


As of 145 PM EDT: Mainly light rain continues to stream across the
forecast area from the southwest this afternoon, but regional radars
show a current lull in upstream activity over northern and central
Georgia. Additional convection in the outer tropical bands of the
Cindy remnants continue to develop over Alabama, and recent HRRR
runs suggest that some of this activity could survive and make a
northeast run across our forecast area later this evening. Rainfall
rates have been meager enough so far that any brief evening tropical
convection should not cause any significant hydro issues. There will
also be an uptick in shear through late evening as the 850 mb jet
strengthens to 30 or 35 kt and backs slightly, but daytime
instability has been paltry and should remain so ahead of the
convection. Any passing precipitation should exit to the northeast
shortly after midnight.

Otherwise, transient upper divergence will move up the NC mountains
through the near-term, but the 500 mb ridge over the southeast will
become resurgent to promote subsidence later tonight through Friday.
Drier air will wrap into the region under the building ridge, with
deeper tropical moisture shunted northwest toward the TN border.
Meanwhile, the remnant Cindy circulation will move up the
Mississippi River Valley through tonight and then east through
Kentucky on Friday, but with the deepest moisture west of the
mountain chain through late day. 850 to 500 mb lapse rates do
briefly build to 6+ deg C/km over the western mountains to support
scattered thunder chances there Friday afternoon. SBCAPEs are
highest in southeast piedmont sections Friday afternoon, but with no
triggering and better capping more evident there. Expect more robust
SW winds and gusts with mixing on Friday afternoon.


As of 100 PM EDT Thursday: At the start of the period, robust and
perhaps organized thunderstorms may be ongoing west of the mountains
within the encroaching llvl baroclinic zone and deeper layered
shear. The eastward translation of this feature should be able to
maintain numerous to widespread cvrg of deeper convection into the
NC/GA mountains Friday evening before diminishing east of the Blue
Ridge overnight within the waning instability.

Aforementioned frontal zone remains progged to sag SE through the
cwfa on Saturday. Slow moving front should be able reactivate in the
afternoon, and current timing would suggest the potential for a few
strong storms in the piedmont. The leading edge of a continental
airmass featuring a progrssive lowering of sfc dwpts is expected for
Saturday night.  This front is then progged to stall along the
coastal plain on Sunday and it is shaping up that any additional
showers will be limited to the I-95 corridor to the coast.

Atop the western Carolinas on Sunday though, developing sunshine is
expected with max temperatures about a category below climo and sfc
dwpts toppping out a rather comfortable level.


As of 330 AM EDT Thursday: the medium range looks really nice and
pleasant for the forecast area, as a long wave trough persists
across the Great Lakes and digs into the TN Valley thru the middle
of next week. At the surface, a continental high pressure system
will gradually slide southeast across the Midwest Sunday-Monday and
settle over the southern Appalachians by Wednesday. Given the
gradual drying over the first couple days of the medium range, some
slight chc to low-end chc PoPs will linger, but expect basically dry
conditions for Tuesday and Wednesday. Temps will be as much as 5-8
deg below normal, coolest Tuesday thru Tuesday night. Dewpts will
fall into the 50s, which will feel nice after the humid conditions
we`ve had the last few days.


At KCLT: Widespread light rain continues around the terminal area,
but with all VFR ceilings associated with the precipitation. The
last round of any nearby scattered showers this evening should move
north of the area, with any precip threat ending. However, lower
ceilings will start to develop in the moist boundary layer, with
lowering MVFR clouds likely and IFR quite possible by daybreak.
Anticipate steady improvement to VFR through Friday morning as drier
air wraps in aloft. Gusty winds will develop from the southwest with
mixing on Friday, and precipitation chances are too small to mention.

Elsewhere: Rain and embedded showers continue to cross the terminal
forecast area from the southwest this afternoon, and one additional
round of showers with isolated thunderstorms will be possible this
evening as tropical moisture arrives from Alabama. Anticipate a
downward trend through MVFR with a period of IFR developing in the
pre-dawn hours as conditions dry out aloft. Expect southwest winds
to strengthen on Friday with gusts developing by late morning.
Precipitation chances are too small to mention for Friday afternoon.

Outlook: Abundant moisture will return from the west with the Cindy
remnants Friday night into Saturday. Anticipate fropa and drying
Sunday to usher in a period of drier weather through the middle of
next week.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High  99%     Med   78%     High  92%
KGSP       High 100%     High  83%     Med   74%     High  91%
KAVL       High  85%     High  85%     Med   68%     High  86%
KHKY       High 100%     High  93%     Med   76%     High  84%
KGMU       High 100%     High  82%     Med   76%     High  91%
KAND       High  86%     High  87%     Med   77%     High  88%

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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