259
FXUS62 KCAE 071357
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
957 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.

9:45 AM Update: The early morning forecast remains generally on
track for today. Currently, satellite imagery is indicating a
stratus deck over the CSRA with spotty low clouds elsewhere.
Expect these lower clouds to slowly erode as daytime heating
increases. Still anticipating scattered showers and storms to
develop, but the initiation may be delayed somewhat depending on
how long the lower clouds hang around. Temperatures thus far
have risen into the lower 80s for the most part across the
region.

Early morning discussion: 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 /12Z SUNDAY THROUGH THURSDAY/...
Restrictions possible this morning with low stratus/patchy fog.


Deep moisture across the area today. Satellite and observations
indicating patchy LIFR/IFR ceilings near AGS/DNL. Expect stratus
at those sites at 12z then improving to VFR by 15z. Mainly VFR
at the other terminals with mid level ceilings. 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.
Winds will be light and variable but favor southeast or south.

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.

&&

$$