047
FXUS62 KCAE 061505
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1105 AM EDT Sat Jul 6 2024

.SYNOPSIS...
Moisture increases today with scatter to numerous showers and
thunderstorms expected this weekend. Above normal temperatures
are expected again Saturday with Heat Index values up to 110
possible. Atmospheric moisture remains high through the long
term supporting a chance of showers and thunderstorms each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Heat Advisory in effect from 11am to 8pm for heat index
  values up to 110 degrees.
- Scattered to numerous showers and thunderstorms.
- Isolated Flash Flooding possible

11 AM Update: Satellite imagery is showing that some cumulus are
just now starting to develop, which is a little later than
anticipated, thus I increased the highs slightly for this
afternoon. Temperatures are already in the upper 80s to lower
90s across the region. The other change from early this morning
is that the shower and storm development will likely be delayed
somewhat, so pushed back the initial PoPs an hour or two.

3 AM discussion: Temperatures this morning remain quite warm in
the upper 70s and lower 80s with some convective debris clouds
over the western Midlands. This may set the stage for another
hot day with high heat index values. Water vapor imagery shows
an upper trough moving through the Great Lakes region with the
upper ridge holding strong across Florida and south Georgia. At
the surface, an weakening frontal boundary is expected to push
into the forecast area this afternoon, which may aid in
providing a focus for convective initiation.

Instability is forecast to be moderate with MLCAPE values
500-1000 J/kg, though wind shear remain generally weak. The axis
of deeper moisture with PWATs around 2.3-2.5 inches will
combine with instability and low level moisture convergence to
promote scattered to numerous thunderstorms initiating after
16z-17z with better coverage across the forecast area compared
to yesterday, with some sea breeze interaction as well over the
eastern Midlands. Overall severe threat appears low but cannot
rule out an isolated severe thunderstorm threat, but think there
is an isolated flash flood threat as well with any training
storms due to the excessively high atmospheric moisture and WPC
has the area outlooked in a slight risk for excessive rainfall.
Storms are likely to linger into the overnight hours due to
interacting outflow boundaries until the instability wanes after
midnight.

The combination of high temperatures and elevated dewpoints and
humidity should result in heat advisory criteria being met
across the forecast area. Confidence is a bit lower today given
the expectation of more widespread convection, depending on when
it develops. Heat indices could reach as high as 110 degrees
before storms develop. Overnight lows expected to be very warm
again in the mid to upper 70s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
Key message(s) - Not as hot with an increase in convective
activity.

A fairly static upper level pattern will be in place across the
Eastern U.S. early next week with an level trough over the
Upper Great Lakes and Central Mississippi River Valley and a
downstream H5 ridge over the Southeast U.S. A diffuse frontal
boundary over The Midlands and CSRA will be the focus for an
increased probability of showers and thunderstorms on both days.
More extensive cloud cover should result in high temperatures
closer to normal for early July. In addition, precipitable water
values in excess of two inches will increase the risk of
locally heavy rainfall near stronger thunderstorms.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Key Message(s) - More typical summertime weather across the
region.

High pressure aloft should be over the Western Atlantic Ocean
next week and the upper level trough over the Great Lakes
weakens as the week goes on. Precipitable water levels will
remain in excess of two inches. Scattered to numerous afternoon
and evening thunderstorms are expected each day with the
potential for locally heavy rainfall. Temperatures will be near
to slightly above normal for mid July.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions generally expected through the TAF forecast
period with afternoon convection expected.

A frontal boundary is expected to stall near the area today
providing a focus for shower and thunderstorm development this
afternoon. Winds expected to be light and variable through
sunrise, then pick up from the south around 5 to 7 knots late
morning. Abundant moisture with increased instability should
result in numerous showers and thunderstorms this afternoon and
have included this in the forecast mainly from 20z to 00z. IFR
vsby in heavy rain possible along with variable gusty winds.
Stratus development is also anticipated late in the TAF period.


EXTENDED AVIATION OUTLOOK...Restrictions possible in diurnally
driven showers and thunderstorms each day. Sunday is expected to
have the highest coverage in the extended period.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Heat Advisory until 8 PM EDT this evening for SCZ016-018-
     020>022-025>031-035-037-038-041-115-116-135>137.
GA...Heat Advisory until 8 PM EDT this evening for GAZ040-063>065-
     077.

&&

$$