439
FXUS62 KGSP 050001
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
801 PM EDT Thu Jul 4 2024

.SYNOPSIS...
Hottest day of the week expected on Friday. A cold front moves in
from the north on Friday night, increasing shower and thunderstorm
chances into the weekend. A typical seasonal pattern of afternoon
showers and storms will start Monday.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 5:25 PM Thurs: We continue to see only a handful of isolated
showers over the NC mtns and into the foothills over the past few
hrs, and have yet to observe any lightning over our fcst area. It`s
looking like temps have peaked and are now beginning to come down a
bit which should further diminish any sfc-based instability across
the area. Conditions should be calm overnight with lows about 2 cat-
egories above normal for early July.

Otherwise, the southeast continues to be steadfast in a strong area
of high pressure, with no signs of relief in the near term. Flow aloft
remains broad and with weak anticyclonic winds across the south and a
strengthening Bermuda high to the east, off the coast of the Carolinas.
On Friday, a boundary off to the west starts to progress toward the
CWA, increasing moisture. PWATs approaching 2 inches, especially in
the southern counties is expected. Higher moisture content bumping
up dewpts will bring concern for high heat index values. Confidence
has increased for more widespread 105 heat indexes Friday afternoon.
A Heat Advisory for most counties outside the mountains will be in
effect 11 am to 8 pm on Friday. Given the additional moisture and
instability, showers and thunderstorm chances return, especially for
the mountain zones (50-70%). Heights should start to fall toward the
end of the period, bringing slightly cooler temps into the short term.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 215 pm EDT Thursday: The flow aloft atop the southern
Appalachians and vicinity will become increasingly cyclonic during
the short term, as a series of short waves traversing the
northern-central part of the country carves out a long-wave trough
centered just west of our region. Meanwhile, a Bermuda high is
expected to steadily retrograde across the western Atlantic,
supporting a very moist southerly fetch (precipitable water values
generally greater than 1.75") across much of the southeast quadrant
of the country. In association with the upper trough, a surface
boundary will be quasi-stationary across, or near our CWA through
the weekend. These factors are forecast to enhance diurnal
convective chances Saturday and Sunday afternoon/evening, with the
best coverage (likely PoPs) expected across southern and eastern
zones...closer to the frontal boundary both days. Having said that,
with the already-weak front expected to become increasingly diffuse,
ample moisture and instability will be in place west of the front to
support at least scattered convection both days. High moisture
content will support some rick of localized excessive rainfall and
flash flooding...especially where training cells and/or slow-moving
multicell clusters are able to develop. Wind shear will remain weak,
so the severe storm potential will be limited to perhaps a few pulse
storms.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 225 pm EDT Thursday: Upper trough across the central Conus
will continue to be reinforced by short waves sweeping across the
northern part of the country early in the period, before possibly
lifting into the northeast quadrant of the country toward mid-week.
Some degree of a weak surface reflection...in the form of a boundary
or surface trough will remain across our near the forecast area
through the period. Meanwhile, Bermuda high will maintain general
southerly flow and more-than-adequate moisture to support good
coverage of diurnal convection through the period...with coverage
expected to be a little higher than climo most days (generally
likely across the mtns, 40-50% across the Piedmont). Temperatures
are expected to be near-to-a-little above climo.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Expect VFR conditions to continue thru
the 00z taf period at all sites. The only exception will be
restrictions associated with convection that directly impacts
the terminals Friday afternoon/evening. I`ve handled this with
PROB30s for TSRA for all the taf sites beginning in the aftn.
Since KHKY and KAVL will likely see better coverage of showers
and thunderstorms on Friday, I have a TEMPO for TSRA beginning
at 21z at KHKY and prevailing SHRA with a TEMPO for TSRA at KAVL
beginning around 19z. Otherwise, winds will remain light and
generally from the S to SW tonight and into tomorrow morning.
They will pick up from the SW later tomorrow morning and remain
SWLY for the rest of the day/evening.

Outlook: Diurnally-driven convection will continue each day thru
the weekend and into early next week, leading to sct showers and
thunderstorms and possible restrictions each afternoon/evening.
Fog and/or low stratus may develop each morning, especially over
areas that received rain the previous day.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 11 AM to 8 PM EDT Friday for GAZ018-026-028-
     029.
NC...Heat Advisory from 11 AM to 8 PM EDT Friday for NCZ036-037-056-
     057-069>072-082.
SC...Heat Advisory from 11 AM to 8 PM EDT Friday for SCZ008>014-019-
     104>109.

&&

$$

SYNOPSIS...CP
NEAR TERM...CP/JPT
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...JPT