Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 272354
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
654 PM EST Mon Feb 27 2017

.SYNOPSIS...
Southerly flow has returned temperatures to above-normal. A warm
front will lift north through the area Tuesday warming temperatures
further and then a cold front crosses the area Wednesday night
with generally light rainfall. Cool high pressure behind a late
week reinforcing front returns temperatures to near normal briefly
Friday and Saturday but temperatures rebound quickly Sunday and
Monday back to above-normal as the high slides offshore.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 645 PM EST: KGSP radar shows the northern extent of a rain
band moving east across the Lakelands early this evening. Some light
precip was probably reaching the ground in that area. Elsewhere...
the precip was probably not reaching the ground. Will hold onto a
small chance over the east, but for the next several hours, it looks
like it will be mostly dry.

Precip chances are still expected to improve a bit later this
evening as weak upper jetlet divergence increases atop the forecast
area and then a period of weak upglide develops in the improving low
level moisture through late evening. The upper level forcing and
deeper moisture will slide off to the east overnight, but with
continued lower level moisture and weak upglide to produce some
drizzle. Mins will be rather warm given the abundant clouds. The
high peaks will be the main exception and we cannot rule out a few
flurries above 5500 feet with any precip tonight, but no
accumulations.

Upper heights will recover a bit through Tuesday. Low level
moisture will persist mainly over the mountains with a continued low
level southwesterly upslope flow. Slightly deeper moisture will
return again from the west to affect mainly the mountains in the
deep layer SW flow through Tuesday afternoon. Upslope triggering
there may keep scattered showers going through the day, with an
isolated thunderstorm possibly in the far southwest mountains during
the afternoon. Piedmont lapse rates should spike around 6.5 deg C/km
with SBCAPE values around 400 J/kg during the afternoon, but
triggers for convection will be hard to find in the lower piedmont.
Will keep PoP generally slight chance east of the mountains. Max
temperatures should reach at least 10 degrees above climo.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EST Monday: The forecast area on Tuesday night will
will be between high pressure off the east coast and low pressure
over the Ohio Valley/cold front trailing into the lower Mississippi
Valley. Warm southwest flow and cloudiness will keep overnight lows
in the 50s even at the highest elevations. A few showers are
possible with the highest probability in the North Carolina
mountains.

The cold front will advance eastward on Wednesday reaching the
western parts of the forecast area late in the day. A very warm day
is in store with highs in the middle 70s outside of the highest
elevations. Showers and thunderstorms will spread across the
northwestern half of the forecast area in the afternoon and then
move across the rest of the area Wednesday evening.

The wind fields with the storms Wednesday afternoon and evening will
be impressive with 40-50 knots of 0-3 km shear expected. However,
the thermodynamic environment will be weak with CAPES of only 300-
400 J/kg expected. Thus, any storms that organize may be capable of
producing wind damage. Will maintain the mention of severe weather
possible in the Hazardous Weather Outlook.

The cold front will move east of the area by midnight allowing
cooler and drier air to move into the forecast area. Expect a sunny
day on Thursday with seasonable highs in the 50s and 60s outside the
higher elevations.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
At 200 PM EST Monday...On Friday morning an upper trough will extend
from Hudson Bay to the Gulf states. This trough progresses off the
East Coast by Saturday, while an upper trough reaches the MS River
Valley. The pattern deamplifies by Sunday, with broad low amplitude
upper ridging over the Great Plains, and troughs off the East and
West Coasts. The ridge progresses to the Great lakes and Gulf States
by Monday.

At the surface, on Friday morning a surface ridge will be crossing
the MS River Valley. Limited NW flow moisture will be over the
Southern Appalachians, but does not appear to be sufficient for
snowfall production. The surface ridge reaches the Carolinas and
Georgia by Saturday. The ridge moves off the East Coast on Sunday,
while moisture from the Gulf of Mexico spreads north to the Southern
Appalachians. Precipitation chances remain limited over our area
until Monday, when better moisture arrives. Temperatures will cool
from slightly above normal to slightly below normal as cool high
pressure arrives, then will warm to well above normal on the back
side of the surface high and rising heights aloft.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT...VFR through the end of operations this evening. Light
returns seen on radar will probably not reach the ground. A
mid-level cloud ceiling will lower through the evening as moisture
deepens on a SW flow aloft. Sfc wind should be light, initially from
the SE, but the direction could become variable by late evening.
Guidance continues to indicate a lower cloud deck moving up from the
S or SW late tonight. Will keep the general idea that an MVFR-level
ceiling will develop around the start of morning ops. Some of the
guidance suggests that some IFR stratus could be lurking nearby
around daybreak, but think that will not develop unless we get more
precip than expected during the early morning hours. The ceiling
should eventually break up/lift during the middle part of the day,
with wind coming up from the SW. Precip chances are not great enough
in the afternoon to warrant a mention.


Elsewhere: VFR conditions will persist through the evening hours,
with gradually lowering mid level clouds becoming lower VFR
stratocumulus. Cigs are expected to lower further during the
overnight hours with mainly MVFR throughout. As with CLT, cannot
rule out a brief IFR ceiling, especially at KAND. Winds will become
light N to NE this evening, then return to SE through later Tuesday
morning.

Outlook: Chances for restrictions diminish somewhat Tue night
into early Wed. A cold front will approach from the west late
Wednesday and bring additional chances of showers and restrictions,
as well as some thunderstorms. Drier conditions end the week
following the fropa.

Confidence Table...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High 100%     High  96%     High  86%     High  97%
KGSP       High 100%     High  81%     High  93%     High  93%
KAVL       High 100%     High  96%     High  86%     High  91%
KHKY       High 100%     High  89%     Med   79%     High 100%
KGMU       High 100%     Med   77%     High  87%     High  89%
KAND       High 100%     High  86%     High  94%     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:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...JMP
NEAR TERM...HG/PM
SHORT TERM...SW
LONG TERM...JAT
AVIATION...PM



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