582
FXUS62 KGSP 041839
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
239 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 145 PM Thursday: 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. This afternoon, guidance from the CAMs
is yet again in disagreement with any convection or showers. Looking
at sounding profiles, much of the CWA is in a stout inverted-V
profile, with an abundance of mid-level dry air. Given the amount of
instability at the sfc and daytime heating, a few showers and
thunderstorms are possible over the mountain terrain. Not expecting
severe storms but cannot rule out an isolated threat. Main hazards
would be gusty winds and cloud to ground lightning. These should
diminish toward sunset as instability gets cutoff. Conditions should
be calm overnight. 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 dewpoints 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 11am-8pm 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 /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions are expected to prevail across
all terminals during the TAF period. SCT cirrus and stratocu this
afternoon with a few showers or thunderstorms possible at KCLT and
KAVL. Confidence is low for severe storms and exactly where these
storms could develop. Will keep a TEMPO at KAVL and KCLT this
afternoon for TSRA. Winds will remain SW and light this evening and
at some sites, become calm overnight. There could be some VSBY
issues with developing stratus in the mountain terminals if rain
falls this afternoon, though confidence is low. Friday, expect
similar conditions with more widespread thunderstorm activity
ramping up during the afternoon time frame once again. Winds should
remain S/SW through the end of the TAF period.

Outlook: Convection will continue into early next week, leading to
scattered TSRA and possible restrictions each afternoon/early
evening. Fog and/or low stratus may develop each morning, especially
for 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
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...CP