455
FXUS62 KGSP 050252
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1052 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 NIGHT/...
As of 10:25 PM Thurs: We have been shower-free across our area
since about 9 pm with much of the stronger convection to our west
also having fizzled out over the past few hrs. Winds have gone
light to calm at most of our sites with conditions expected to
remain quiet overnight with lows about 2 categories above normal
for early July.

Otherwise, the southeast will remain under relatively flat upper
ridging thru the near-term period. On Friday, a weak sfc boundary
to the west will approach our CWA helping to increase low-level
moisture across the area. Expect PWATs to approach 2 inches, es-
pecially over our southern zones. With temperatures expected to
reach the mid to upper 90s, the higher dewpts will likely produce
heat index values of 105 degrees across the majority of our non-mtn
zones Friday afternoon. As such, a Heat Advisory for those counties
remains in effect from 11 am until 8 pm on Friday. The higher dewpts
should also help produce considerably more sfc-based instability on
Friday. This will result in sct to numerous showers and thunderstorms
across our area for the aftn and evening, with the best best coverage
expected over the higher terrain. The severe threat still appears
minimal for most of our fcst area on Friday, however SPC does have
a portion of our NC mtn zones in a Marginal Risk area for Day 2.
The main hazard will likely be gusty winds from strong downbursts.

&&

.SHORT TERM /SATURDAY 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 /03Z 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-
     057-068>072-082.
SC...Heat Advisory from 11 AM to 8 PM EDT Friday for SCZ008>014-019-
     104>109.

&&

$$

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