-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 151743
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
143 PM EDT Mon Apr 15 2024

.SYNOPSIS...
Dry high pressure will linger to our south through 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 in the middle of the week.
A front will approach our area from the west through the middle of
the week, and could bring more showers and thunderstorms by Friday
and into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 132 PM: Sky remained mostly cloud-free across the fcst
area, but a few cu were beginning to form over some of the higher
peaks. No changes.

Otherwise...over the course of the afternoon, the upper trough over
the NE CONUS will move offshore and the ridge to our west will
become the dominant feature for our weather. Westerly flow will
continue in the midlevels, but low-level flow will back to SW over
the Piedmont which will aid in marginal moisture return.  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 and associated mixing, RH will drop into the
lower 30s percent but not quite to the critical level for fire wx;
winds will be too light 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.
-- End Changed Discussion --

&&

.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 /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
At KCLT and elsewhere: VFR at all terminals through the period. Wind
should be S to SW through late today, possibly with some gusts east
of the mtns as we mix deeply. Cannot rule out an isolated shower
over the higher terrain, but not worth including at KAVL. Most of
any low clouds will dissipate with loss of daytime heating. Expect
wind to go light/variable at sunset. On Tuesday...continued fair,
with wind returning light S to SW from mid-morning onward. We
should have better low moisture, so some high-based stratocu can
be expected in the afternoon.

Outlook: Isolated SHRA/TSRA are not out of the question Tue and
Wed afternoons near the NC sites. Otherwise VFR generally will
persist through midweek. An unsettled pattern with precip chances
and periodic restrictions may develop Thu-Fri but confidence
remains low.
-- End Changed Discussion --

&&

.CLIMATE...
RECORDS FOR 04-15

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      89 1972     42 1943     64 1887     23 1907
   KCLT      89 1936     46 1889     66 2006     28 1907
   KGSP      91 2006     45 1913     69 1922     22 1907



RECORDS FOR 04-16

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      87 2006     42 1905     62 1945     26 1943
   KCLT      89 2006     49 1890     64 1998     29 2008
                1896                    1991        1962
                                        1945
   KGSP      88 1888     54 1903     64 1945     24 1907

&&

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

&&

$$

SYNOPSIS...TW
NEAR TERM...PM/Wimberley
SHORT TERM...TW
LONG TERM...TW
AVIATION...PM
CLIMATE...