888
FXUS62 KCAE 070848
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
448 AM EDT Sun Jul 7 2024

.SYNOPSIS...
Abundant moisture combined with an unstable air mass should
support scattered to numerous showers and thunderstorms
today and Monday. Above normal temperatures are expected again,
with Heat Index values above 100 each day through next week.
Atmospheric moisture remains high through the long term
supporting a chance of showers and thunderstorms each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key message(s) - Slow moving storms/potential for isolated flash
flooding.

Upper level ridge centered to the south of the area, from the
eastern Gulf of Mexico across Florida. Upper level flow is
generally west-northwest over the ridge. A weak frontal boundary
appears to set up in the SC Piedmont southwest across east-
central GA. Water vapor this morning is showing deep moisture
across the area. Precipitable water will be near 145% of normal,
about 2 to 3 standard deviations above normal...with values up
to around 2.5 inches this afternoon and evening aided by modest
south/south-westerly 850mb-700mb moisture flux. Expect
considerable low clouds this morning with possible delayed
heating. Guidance temperatures are a few degrees cooler for max
temps due to clouds/weak temp advection but still moderately
unstable by the afternoon with long "skinny CAPE" and quite
moist deep looking soundings. The "warm" cloud extends above
12000 ft and with weak boundary layer flow, there is a threat
for locally heavy rain. Strongest instability appears to be near
the AGS area. The CAM models have different solutions but in
general show scattered coverage, maybe more numerous in the
CSRA. The GFS/ECMWF suggest greatest convective coverage early
in the Upstate near the frontal boundary where low-level
convergence will be maximized then developing southeast into the
Midlands/CSRA late into the evening, maybe enhanced by a weak
mid level short wave coming over the ridge. Convection could
linger overnight but expect a diminishing trend after midnight.
This seems reasonable and the NBM has highest pops in the
west/likely and chance in the east, so stayed close to this
idea. The main threat from storms today will be for potential
flash flooding due to slow moving storms in a high precipitable
water environment. The CSRA will especially need to be watched
for potential flash flooding after yesterday`s extensive
rainfall. Temperatures close to the mean of the guidance,
perhaps slightly warmer, around 90 degrees. Muggy conditions
tonight, mid 70s for lows.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Key Message(s):
- Anomalously high atmospheric moisture
- Scattered to numerous diurnal thunderstorms
- Isolated flash flood threat

Little change in atmospheric conditions this period with
anomalously high moisture with PWATs in the 2.3-2.5 inch range
early this week. Aloft, a persistent upper ridge remains in
place over the southeastern states while the remnants of Beryl
lift northward through east Texas by Monday night. The forecast
area remains under the influence of upper ridging on Tuesday
between the remnants of Beryl lifting northeastward into the
Mississippi Valley and western Ohio Valley and an upper low over
the western Atlantic diving southwestward to the Florida coast.

Expect scattered diurnal convection each day with the details in
location and exact timing likely ties to mesoscale boundaries
in the absence of any upper level features, with the sea breeze
likely to play a role favoring higher pops on Monday. Moderate
instability is forecast along with continued weak shear
resulting in generally low severe chances outside of an isolated
pulse severe storm and isolated flash flooding due to very
efficient rainfall rates and slow moving storms. Temperatures
should be a bit cooler due to cloud cover with highs expected in
the lower 90s but heat indices are still expected to exceed 100
degrees.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Key message(s):

- Daily diurnal showers and thunderstorms
- Heat indices exceeding 100 degrees
- Isolated flash flooding threat

Global ensembles continue to favor anomalously high 500mb
heights through the extended forecast period with the upper
trough over the central US weakening and lifting north through
the end of the week. Atmospheric moisture remains high with LREF
showing more than 50% of its members forecasting PWAT values
greater than 2 inches supporting a heavy rain threat. The
presence of the upper ridge over the southeastern states
continues to support weak shear, typical of summer, and this
combined with the high moisture content and above normal
temperatures should result in scattered diurnal convection and
the possibility of slow moving storms that could lead to an
isolated flash flooding threat. Heat indices are expected to
exceed 100 degrees each day and could approach heat advisory
criteria late in the week.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
Restrictions expected toward morning with low clouds and patchy
fog.

Deep moisture across the area today. Satellite and observations
indicating scattered low clouds at 06z with mid and high level
ceilings. Models are suggesting stratus will develop toward
daybreak with relatively high confidence for MVFR conditions
with areas of IFR ceiling/visibility after 09z with highest
confidence at the AGS/DNL terminals. Low clouds will be slow to
erode but by 15-18z expect VFR ceilings and light and variable
winds favoring southeast-south. Scattered to numerous
thunderstorms expected to develop in the afternoon as air mass
will be moist and moderately unstable. CAM models show different
solutions but think thunderstorms will develop in the SC
Piedmont near the front and expand to the east/southeast during
the late afternoon and early evening. Thunderstorms will be
capable of producing heavy rain/reduced visibility at times.

EXTENDED AVIATION OUTLOOK...Restrictions possible in diurnally
driven showers and thunderstorms each day. Early morning low
stratus possible.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.

&&

$$