Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS62 KGSP 200011

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
811 PM EDT Fri Apr 19 2019

A strong cold front will move across the forecast area through this
evening bringing showers and thunderstorms to the region. Cooler
temperatures and lingering showers are expected behind the front.
Temperatures will warm again by early next week.


As of 800 PM: Final line of deep convection approaching the I-77
corridor, but is on a weakening trend. Latest SPC mesoanalysis shows
only about 500 J/kg along the line with little instability left to
work with as it tracks east. Given that the line has been sub-severe
when it was in an environment with over 1000 J/kg of CAPE, I think
we can let the Tornado Watch expire at 800 PM. Gusty winds of 30-40
mph cannot be ruled out in spots along the line thru about 1000 PM,
but otherwise, things are winding down.

There is still a lot of ongoing flooding in the western third of the
CWA due to run off. Fortunately, additional precip associated with
the approaching upper low is very light.

That upper low can be easily seen on WV and area radars, spinning
over northern AL, drifting into central TN. Meanwhile, the
associated sfc low was analyzed over ern TN, with a trailing front
has pushing into the wrn part of the FA. Gusty SW winds will
continue behind the front with strong llvl CAA.

Forcing and, to some extent, moisture will taper off overnight, but
falling heights over the mountains suggest precip may redevelop
there. The low will begin to move northeast and across the
Appalachians. As temps drop behind the cold front, there is
potential for the coldest spots (high elevations) to see this precip
change from rain to snow. SLRs will not be particularly good owing
to shallow moisture present at that time, and low-level flow remains
southwesterly, thus being less favorable for upslope forcing on the
majority of the ridges. Conditions look much more favorable after
daybreak, when the column saturates over a deep layer beneath the
core of the upper low. Most of the area will be subject to scattered
light rain showers during the day as a result. However, in very high
elevations (almost entirely above 5000 ft) will cool early enough,
and remain cold long enough, that accumulating snow of several
inches is possible. These areas currently appear too small/isolated
to warrant a Winter Weather Advisory. Can`t absolutely rule out some
evaporative cooling that will allow a few flurries to be experienced
in populated areas of the mountains and foothills during the morning.


As of 230 PM EDT Friday: The mid level low pressure system will
pivot just north of the area on Saturday night before pulling away
to the northeast on Sunday. Lingering wrap around showers will
mainly impact the mountains on Saturday night. Some snow is expected
at the higher elevations on Saturday night with around 1
accumulations expected at the highest elevations.

A drying and warming trend will occur Sunday night and Monday as
high pressure builds into the area.


As of 200 PM EDT Friday: Mid level ridging and surface high pressure
will be in place across the region for Tuesday and Wednesday.
Conditions should be dry and warm with highs reaching into the lower
80s in the Piedmont by Wednesday. A mid level trof and associated
cold front will appreach the area from the northwest late in the
week with an increasing chance of showers.


At KCLT and elsewhere: One final line of deep convection currently
crossing the eastern Upstate and the NC Piedmont to start the 00z
TAFs. Expect the convection to continue to slowly weaken, with
little lightning left. The line should cross KHKY and KCLT between
00-02z, producing brief torrential downpours and gusty winds. Cannot
rule out TS, but confidence level warrants just SHRA for now, due to
the expected weakening. Back to the west, the center of a large
upper low spins over central TN. This low will slowly drift NE,
bringing winds around out of the SW and keeping MVFR to low VFR cigs
around thru much of the overnight and the day on Saturday. Plenty of
shallow showers are developing under the circulation, so expect
periods of -SHRA at any or all the TAF sites thru the period. One
round this evening, then another round Saturday aftn. Overall, the
precip should be light, but may produce occasional MVFR cigs/vsby.
With plenty of mixing overnight and thru Saturday, expect off-and-on
wind gusts, with most gusts this evening and again Saturday aftn.

Outlook: Mainly VFR conditions are expected Sunday and early
next week.

Confidence Table...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High  90%     High  89%     Med   63%     High  86%
KGSP       High  97%     High  89%     High  86%     High  89%
KAVL       High  93%     High  80%     High  96%     High  92%
KHKY       High  90%     Med   79%     High  86%     High  88%
KGMU       High  98%     High  90%     High  86%     High  89%
KAND       High  88%     High  86%     High  90%     High  86%

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:




NEAR TERM...ARK/Wimberley
AVIATION...ARK is the U.S. government's official web portal to all federal, state and local government web resources and services.