Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 221850

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
250 PM EDT Mon Apr 22 2019

Warm and dry high pressure will be in control of our weather until
Thursday.  Low pressure approaches from the west on Thursday and may
linger into the weekend.


As of 245 PM EDT Monday: With surface high pressure continuing to
build in, quiet, Spring-like conditions have prevailed across the
area today with nearly clear skies, light SW winds, and temperatures
well into the low to mid 70s. Do expect temperatures to climb
another degree or two before capping off for the day. Into tonight,
expect nearly clear skies to continue with temperatures dropping
into the lower 50s across the Upstate and NW Piedmont, cooler across
the mountains - overall around normal. Trending from last night, do
anticipate mountain valley fog to develop again late overnight
through before daybreak. Any lingering fog will quickly dissipate
after daybreak.

On Tuesday, sfc high pressure with building ridge aloft will
continue to allow for a dry weather pattern across the western
Carolinas and northeast GA. Expect temperatures to climb well above
normal, with lower 80s, with pockets of 70s across the mountains.


As of 200 PM EDT Monday: An upper ridge will continue to build over
the Southeast states on Wednesday, as a closed upper low tracks into
Texas. Meanwhile, a northern stream trough will dig into the Great
Lakes, and push a weak cold front into the Ohio Valley. Westerly
flow ahead of that front, combined with rising heights aloft should
bump temps about 8-10 deg above normal under mostly sunny skies. The
latest guidance generally agrees that the front will push roughly
thru the NC zones Wed ngt and stall out thru Thursday. The front
will have little moisture to work with, but a few isolated showers
may develop, esp along the TN/NC border with help from WLY upslope.
Lows will be about 10 deg above normal under increasing clouds.

Thursday, the upper low will open up into a southern stream trough
and approach the area from the west. The low-level flow will turn
out of the SW and moisture will gradually increase mainly from the
top-down. There will be an increase in PoP across the west Thu aftn
into Thu night, but the east will likely stay dry. Temps will
continue to be about 8-10 deg above normal.


As of 230 PM EDT Monday: There is still some disagreement among the
guidance on with the merging of the split stream troughs over the
eastern states Thursday ngt thru Friday. The 12z GFS agrees fairly
well with the ensembles and the 00z ECMWF on better phasing of the
upper troughs and a cleaner fropa of the associated front. The front
should cross the area early Fri morning thru Fri aftn. Based on that
timing, most of the destabilization will occur from the I-85
corridor and east. Even then, sbCAPE looks to be only a few hundred
J/kg. Shear does not look that impressive, and the way the front
lays over the area from the NW doesn`t result in very strong frontal
convergence. So the severe threat, while probably non-zero, should
be low on Friday. Precip should move out to the SE by early Friday
evening, with gradual clearing. Temps will remain above normal.

Dry high pressure briefly builds in Saturday under quasi-zonal flow
aloft. The a series of shallow impulses will ripple thru the flow
with guidance quickly out of phase of timing associated weak fropas
from Sunday thru the first half of next week. Overall, conditions
should be dry (with some slight chcs possible, mainly in the
mountains) with temps near to slightly above normal.


At KCLT and elsewhere: Aside from the potential for mountain
valley fog tomorrow morning, once again, expect VFR to prevail
through the valid TAF period with sfc high pressure influencing the
current weather pattern. With periods of passing thin cirrus and
nearly clear skies, expect winds to become light and variable
tonight, with light SSW winds Friday morning, AOB 5 kts.

Outlook: Aside from the potential for mountain valley fog in the
morning, expect VFR conditions to prevail through mid week. Periods
of showers and thunderstorms associated with a few cold front will
bring the potential for showers and thunderstorms towards the end of
the week, with flight restrictions possible.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     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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