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000
FXUS62 KGSP 150750
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
350 AM EDT Mon Apr 15 2024

.SYNOPSIS...
Dry high pressure will linger to our south into the first half
of the week giving our region above normal temperatures and more
humidity than we`ve felt lately. Small chances of showers and storms
do return to some areas of the mountains today and Tuesday as a
result. A front will approach our area from the west through the
middle of the week, and could bring more showers and thunderstorms
by Friday into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM: Skies are clear across the CWA, with midlevel clouds
having advected out with the departing shortwave. Over the course
of the day today, the upper trough over the NE CONUS will move
offshore and the ridge to our west will become the dominant feature
for our weather. A light southwesterly return flow will result in
still higher dewpoints. As partial thicknesses continue to rebound
temperatures will also trend warmer, well into the 80s, within a few
degrees of record highs. Owing to the very warm temps, RH will drop
into the lower 30s percent but not quite to the critical level for
fire wx; winds will be too low for Fire Danger statements as it is.

With the influence of the ridge diminishing, the warm conditions
appear to mix out the subsidence inversion, such that a respectable
amount of SBCAPE is generated by many of the models. We are for
want of a trigger mechanism. Embedded shortwave will pass thru
the middle OH Valley into Virginia today, but heights remain on an
upward trend owing to the migration of the ridge. Nonetheless, the
GFS/ECMWF/GDPS develop spotty QPF response over our mountains. Based
on CAM output, this looks to be especially isolated and worthy
only of a brief isolated shower/t-stm mention near the Blue Ridge
Escarpment. Soundings are very dry aloft and updrafts may not
amount to much especially given minimal trigger. Any such storms
should diminish diurnally; some CAM runs hint at semi-organized
convection moving off the frontal zone in the OH Valley and
propagating southward into our northern CWA. The chance of that
appears no greater than before; we had previously carried a small
PoP in our north as a nod to that possibility. In light of recent
model runs have moved the overnight PoP to late evening in our
northern mountains. Partial convective debris clouds do stand
a good chance of reaching the CWA, so a partly to mostly cloudy
night is expected in the I-40 corridor. Mins tonight again 10 or
more degrees above normal with light winds.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 331 AM Monday: The short term forecast period kicks off
Tuesday morning with a northern stream trough over New England and a
potent closed upper low over the central Great Plains. Upper ridging
ahead of the encroaching Plains low will slide into the Appalachians
Tuesday. At the same time, a lead shortwave perturbation trapped
south of the ridge is forecast to swing across the Southern
Appalachians and may provide just enough forcing to instigate
isolated to scattered showers and thunderstorms mainly along and
north of the I-40 corridor. Should any deep convection materialize,
a conditional threat for a few strong to marginally severe storms
will be possible. Modest surface-based instability and around 30kts
of deep-layer vertical wind shear would support locally damaging
winds, especially with inverted-v profiles apparent in near-storm
forecast soundings. By Wednesday, the Great Plains upper low is
progged to quickly lift into the Midwest and gradually become
absorbed into a large sprawling northern stream longwave trough
dropping out of the Canadian Prairies. As such, available forcing for
ascent wanes through the day with only weak height falls and
weakening wind fields. A weak band of convection will likely
encroach on the mountains late Wednesday afternoon into the evening
ahead of a surface cold front pushes across Tennessee. The lack of
upper forcing, however, should greatly limit coverage with only
isolated to scattered showers and storms expected.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 342 AM Monday: A low confidence pattern takes shape late week
into the weekend as the previously mentioned sprawling longwave
trough slowly makes its way along the Canadian border and off the
New England coast by Sunday. This is expected to be a very broad and
flat trough which results in a prolonged period of quasi-zonal flow
across much of the country east of the Rockies. Thursday will be dry
and very warm with downsloping flow and rising heights and warming
low-level temperatures. Thereafter, a much stronger cold front is
anticipated to drop through the Ohio Valley heading into the weekend
and eventually into the Appalachians. Multiple embedded shortwave
perturbations in the quasi-zonal flow ahead of the front will allow
rain chances to gradually return on Friday with the front pushing
into the area over the weekend. Guidance also depicts a more well
defined shortwave trough sliding across the Gulf states and into the
southeast late weekend, which would result in a more focused period
of increased rain chances.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR, with SW winds thru the period at
all sites except KAVL, where initially NW winds are likely to
go light/VRB as SW flow regime strengthens during the day, and
eventually should go SW by late afternoon. Some low-end gusts
likely less than 20 kt are possible at all sites during the
afternoon. A diurnal cu field should develop in the afternoon
over the mountains and foothills, with bases comfortably VFR. A
stray SHRA or TSRA is possible near KAVL and KHKY but chance too
low to mention. Some convection developing along frontal boundary
across KY/VA may propagate south into the northern NC mountains
this evening to very early Tue morning, but resultant chance of
SHRA/TSRA is even lower at the terminals. Midlevel clouds and/or
cirrus debris likely will spill over the NC sites overnight however.

Outlook: Isolated SHRA/TSRA are not out of the question Tue and
Wed afternoons near KAVL and KHKY. Otherwise VFR generally will
persist through midweek under high pressure regime.

&&

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

&&

$$

SYNOPSIS...TW
NEAR TERM...Wimberley
SHORT TERM...TW
LONG TERM...TW
AVIATION...Wimberley