Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 281449

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1049 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 1045 AM EDT: Water vapor loop shows the upper trough
associated with the upper low to our north moving east of the area
soon. There does appear to be a short wave rotating around the upper
low behind the trough that will move across the area this afternoon.
12z observed RAOBs and meso analysis show decent mid level lapse
rates over the area this afternoon. Instability is beginning to
build and 40 knots of bulk shear is moving across the area as well.
Still looks like the best overlap of instability and shear will be
along and east of the I-77 corridor this afternoon. SPC has that
area in a marginal risk for severe, and this looks good and in line
with our current HWO. There may be some showers or isolate storms
west of there, but coverage and risk of severe will be much lower as
mid level warming moves in behind the upper system limiting
instability. Have updated PoP trends to show these features. Current
high temps still look on track.

Upper ridging will develop tonight as a surface cold front gradually
settles off to the southeast by daybreak Wednesday. The dry forecast
and above normal temps continue.


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.


At KCLT: A few MVFR clouds are developing in the moist air mass this
morning. Do not expect a ceiling until heights rise to low VFR, but
can`t completely rule one out. Guidance still shows convection
developing near the area around 19z. SW winds with low end gusts
expected through most of the day. Winds turn WNW with fropa during
the evening hours and slackening overnight.

Elsewhere: Precipitation will be sparse the rest of the period as
drier air is working in aloft from the west. However, low levels
remain very moist and tempo MVFR cigs are possible until early
afternoon before conditions return to VFR. Coverage along the
approaching boundary this afternoon should be less across the
mountain/foothill sites than at KCLT. Southwest winds will be gusty
at times ahead of the front, turning northwest with fropa later this
evening. Winds will remain NW at KAVL throughout.

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...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       High  93%     High 100%     High 100%     High 100%
KGSP       High  97%     High 100%     High 100%     High 100%
KAVL       High  98%     High 100%     High  80%     High  91%
KHKY       High  94%     High 100%     High 100%     High 100%
KGMU       High  97%     High 100%     High 100%     High 100%
KAND       Med   72%     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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