Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 290725

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
325 AM EDT MON AUG 29 2016

A tropical system will move toward the North Carolina Outer Banks
through Tuesday before likely moving back out to sea by mid week. A
cold front will approach the region from the northwest Wednesday
night into Thursday, with another tropical system likely emerging
from the Gulf of Mexico. There remains a great deal of uncertainty
with the Gulf system but there are no imminent threats to our area
at this point.


As of 300 AM, Broad circulation associated with weak upper low off
the GA coast shows up nicely in water vapor imagery early this
morning. We are still seeing some light radar returns showing up
within the outer reaches of this circulation as far west as the NC
Triad, although cloud bases associated with these returns appear to
be quite high, and we have yet to see any precip being reported at
the surface. Some mesoscale models indicate shower potential across
our SE zones this morning, although based upon the latest radar
trends upstream, this appears to be a bit too aggressive.
Nevertheless, will allow pops to creep into the slight chance range
across our southern tier after sunrise.

NE low level flow will maintain relatively low theta-E across much
of the forecast area through the near term. Again, an isolated cell
or two can`t be ruled out into the afternoon across the southern
Piedmont, but chances appear to be slight at best. The only other
real area of convective potential is expected to be over the mtns,
where instability may be maximized later today. However, chances
will be low even there. In fact, some of the latest mesoscale model
guidance does not initiate any convection over the high terrain this
afternoon. Nevertheless, it doesn`t hurt to advertise a slight
chance this afternoon, mainly near the TN border. Temps through
tonight are expected to be a degree or two cooler than on Sunday,
but still slightly above normal. Overall, a not-too-shabby day for
late August.


As of 310 AM Monday, the system currently known as Tropical
Depression Eight will likely track off the NC Outer Banks on
Tuesday. Over the forecast area, short range models indicate that
the eastern edge of a large 590+ DM ridge will remain overhead,
centered over the central CONUS. Forecast soundings indicate that
the environment will see a deep layer of warm air between H7-H4. By
the heat of Tuesday afternoon, the region will likely see areas of
weak CIN persisting. I will expect only iso mtn SHRA/TSRA Tuesday
afternoon, with sct convection near the TN/NC line. High temperatures
are forecast to range from the mid 80s within the mtn valleys to
around 90 east.

Wednesday, the tropical cyclone near the Outer Banks should continue
to track NE off the coast as the system currently known as Tropical
Depression Nine begins to lift over the waters of the eastern Gulf
of Mexico. A weak cold front will approach the southern Appalachians
from the north, reaching the Ohio River Valley by the afternoon.
Thermal profiles on the forecast soundings indicate very little
change from Tuesday. I will forecast sct ridgetop convection with
isolated coverage across the mtns and adjacent foothills, areas east
should remain dry. High temperatures are forecast to range within
one degree of values observed on Tuesday.


As of 320 AM Monday, Thursday appears to be the most active day
during the extended period. A cold front is expected to sweep from
north to south across the forecast area during the daylight hours.
The system currently known as Tropical Depression Nine is expected
to push across the Big Bend region of FL on Thursday. In addition,
medium range models indicate that the axis of a H5 longwave trof
will ripple over the Blue Ridge Thursday afternoon. The combination
of deep moisture, the passage of the H5 trof, and a sweeping front
should support at least sct coverage of thunderstorms on Thursday.
Sfc temps may warm quickly ahead of the cold front, possibly
reaching the mid 90s east of I-85.

Friday through Sunday, GFS and ECMWF indicate that a large Canadian
air mass will surge south in the wake of the cold front and tropical
cyclone. I will indicate generally dry conditions from Friday through
the weekend. High temperatures should range very close to normals,
around 80 within the mtn valleys to mid to upper 80s east.


At KCLT and elsewhere (except KAVL): VFR conditions are forecast
through the period. Moisture rotating around weak/broad circulation
off the GA coast could result in a few light showers and/or a brief
MVFR/low VFR cigs later this morning, but opted to advertise only
SCT low clouds, while precip chances aren`t worth a mention attm.
Otherwise, NE winds will continue through the period, maintaining a
relatively dry/stable air mass that should keep any convection from
developing this afternoon.

At KAVL: conditions appear ripe for a fog/low stratus even later
this morning. Tempos for LIFR conditions are included after 08Z,
becoming prevailing by 08Z. Would not be surprised to see at least
brief periods of VLIFR. Conditions should improve to VFR shortly
after sunrise. Isolated convection is expected over the mtns this
afternoon, but the bulk of this activity should remain west of

Outlook: Ridging will persist across the region through mid week.
Convective chances may be limited by sinking air to the west of a
tropical system at the coast. Patchy fog will be most favored in
mountain valleys.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       High 100%     High  86%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       Med   75%     High  91%     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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