Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 280852

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
452 AM EDT Tue Mar 28 2017

A cold front will approach from the northwest today and settle
southeast of the area tonight into Wednesday. Drier weather will
develop as high pressure builds southward from eastern Canada along
the east coast. Moisture will gradually return on Thursday, with
abundant moisture setting up by Friday as a strong low pressure
system moves east from the Mississippi River Valley. Drier weather
will return for the weekend.


As of 445 AM EDT: Coverage of any early morning lingering convection
is increasingly getting confined to the eastern piedmont in the
region of better passing upper support. The secondary band of
convection back to the west has pushed southward into central AL/GA
and should pose no further risk of thunder to the region this
morning. Western sections should thus see little to no PoP for the
remainder of the morning hour.

Otherwise, water vapor imagery shows the upper level
wave/circulation lifting quickly northeast into West Virginia with
the trailing trough axis crossing the southern Appalachians early
this morning. The upper trough axis will cross the northern tier
this morning and be generally east of the area by Noon. Mid level
drying will also work in quickly from the west through the later
morning hours. However, the surface cold frontal passage will be a
bit delayed and scattered shower/thunderstorm redevelopment along
the passing front is expected this afternoon, especially along and
east of I-77. Westerly downsloping flow will work against coverage
in most other locations. Upper ridging will develop tonight as the
surface cold front gradually settles off to the southeast by
daybreak Wednesday.


As of 255 AM EDT Tuesday: Upper ridging will build over the area
through Wednesday east of a strong closed low moving across north
Texas. The passing surface cold front will settle well south of the
region and high pressure will nose down east of the Appalachians
from the Great Lakes/eastern Canada through Wednesday night. Despite
the fropa, good insolation will boost temps back into the upper 70s
to lower 80s east of the mountains Wednesday afternoon.

The upstream low pressure system will lift northeast through the
southern plains on Thursday with persistent ridging downstream
across the southeast. Very weak upglide may get reestablished over
the developing cold air damming as early as late Wed. night, with
PoP increasing gradually through Thursday. Will lean toward the
cooler MOS temps for Thursday afternoon with cold air damming onset
quite possible.


As of 255 AM EDT Tuesday: Heights will fall from the mid Mississippi
river valley and the lower OH valley toward the TN river valley
through the day on Friday. This trough should cross our region
Friday night. Improving upglide moisture will get established well
east of this system by Thursday evening and deeper moisture will
arrive mainly Friday through Friday night. The surface low pattern
should evolve in a Miller B type fashion, with gradual erosion of
the wedge layer and instability steadily uncovered from south to
north during the day Friday. This will make thunderstorms quite
possible, and severe weather not out of the question Friday as the
southerly low level jet ramps up.

Dry ridging will return over the southeast Saturday through Sunday.
Temperatures should run generally 5 to 10 degrees above climatology
in most areas over the weekend. Atlantic moisture return around the
high pressure, and associated with upslope flow, may bring some
clouds back into the picture Monday, and possibly light
rain/showers. Temperatures should thus be a bit cooler Monday
afternoon, with less diurnal range.


KCLT: Convection working east across the I-77 corridor early this
morning should be safely east of the airfield before 10Z. Expect
cigs to settle into the MVFR range. IFR is possible but not likely
at this point. Anticipate some recovery to lower end VFR by mid to
late morning, with the trailing surface cold front then approaching
from the northwest for the afternoon hours. Will time the PROB30 for
TSRA along the front to mainly the 17Z to 21Z period. Surface winds
will be southwesterly with possible low end gusts this afternoon,
turning WNW with fropa during the evening hours.

Elsewhere: Thunderstorm chances have ended for the foothill sites
and KAVL. Winds are toggling back toward southwesterly ahead of the
cold front approaching from the northwest. Coverage along the
approaching boundary this afternoon should be less than at KCLT as
drier mid level air works in from the west. Anticipate mainly MVFR
cigs this morning, recovering to VFR by late morning, and with tempo
MVFR for any isold showers/thunderstorms that might form. Southwest
winds will be gusty at times ahead of the front, turning northwest
with fropa later this evening. Winds will remain NW at KAVL

Outlook: Drier conditions should briefly return Wednesday before
another storm system begins affecting the region Thursday through
Friday. Drier conditions will return again for the weekend.

Confidence Table...

            09-15Z        15-21Z        21-03Z        03-06Z
KCLT       Med   72%     High  88%     High 100%     High 100%
KGSP       High  92%     High  98%     High 100%     High 100%
KAVL       Med   70%     High 100%     High 100%     Low   59%
KHKY       Low   50%     High 100%     High 100%     High 100%
KGMU       High  94%     High  88%     High 100%     High 100%
KAND       High  85%     High  83%     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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