923
FXUS62 KCAE 050837
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
437 AM EDT Fri Jul 5 2024

.SYNOPSIS...
Moisture increases into the weekend with isolated to scattered
showers and thunderstorms each day beginning Friday. Above
normal temperatures are expected Friday and 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 Friday for heat indices 105-110 across
  the entire area.

The primary mid-upper level ridge axis continues to pivot east
and is starting to show signs of flattening ahead of the
approaching trough in the central US. Thanks to the ridge
shifting east, southerly low level flow has driven up both
surface dew points and PWAT`s, in the low-mid 70`s and nearing
2.0" respectively. The combination of increasing moisture and
persistent ridging will allow heat indices to rise above 105
today, likely over 110 in spots; NBM 75th percentile high temp
today is 104 at CAE, but increasing moisture and cloud cover
should prevent us from quite reaching that. So "only"
forecasting a high at CAE of 102 with afternoon dew points in
the low 70`s. While moisture and boundary layer heat are
increasing, shower- storm activity will remain limited today as
the ridge related capping and subsidence aloft is still very
evident in all forecast soundings. The best chances (but still
only 20-30%) for convection is across the CSRA and western
Midlands where mid- level capping is slightly weaker and the
overall moisture- instability is slightly more favorable.


&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Key Message(s):

- Heat Indices as high as 110 degrees. A Heat Advisory may be
  needed.
- Scattered to numerous showers and thunderstorms this weekend
- Isolated Flash Flooding threat over the weekend

An upper trough will move through the Great Lakes region
Saturday while a weak frontal boundary pushes into the Carolinas
and stalls near or just west of our forecast area. A very moist
air mass will be in place with PWATs well over 2 inches and
possibly as high as 2.4 inches. Surface high pressure centered
over the western Atlantic will continue to feed moisture into
the area with southerly low level flow. Forecast instability is
forecast to be higher than it has been and the combination of
above normal PWATs, very warm temperatures, instability and low
level moisture convergence should result in scattered to
numerous showers and thunderstorms both Saturday and Sunday.
Cannot rule out an isolated pulse severe threat but widespread
severe weather is not expected. Extremely high atmospheric
moisture and possible training of storms with very high rain
rates may support an isolated flash flooding threat and WPC has
outlooked the area in a slight risk of excessive rainfall for
Saturday.

Heat indices are expected to be high over the weekend with
values forecast over 100 degrees and heat advisory criteria may
be met on Saturday with forecast heat index values 105 to 110
degrees. Confidence is limited though, with the possibility of
convection developing early enough to prevent those values from
being reached.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Key Message(s):

- Heat Indices over 100 degrees
- Daily diurnal convection expected

A persistent and somewhat stagnant pattern is expected in the
extended forecast period with global ensembles favoring positive
500mb height anomalies over the forecast area and mean PWAT
values near or in excess of 2 inches through the period.
Generally expect scattered diurnal convection each day through
the forecast period in a typical summer pattern with near to
above normal temperatures. Cannot rule out an isolated severe
thunderstorm threat.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
VFR conditions expected through the TAF period.

Little to no vsby or cig restrictions are expected this morning
thanks to a strong low level jet driving some boundary layer
mixing all night; some 6k foot stratus is the only feature of
note as of 09z. Southerly winds will pickup later this morning,
with gusts up to 12-15 knots this afternoon. Typical summer cu
also expected throughout the late morning and afternoon.
Shower-storm activity is possible across the CSRA and western
Midlands later today, potentially impacting AGS and DNL but
confidence is too low for any TAF mention at this time.

EXTENDED AVIATION OUTLOOK...Restrictions possible in diurnally
driven convection each day. The greatest convective coverage
expected Sat/Sun afternoon.

&&

.FIRE WEATHER...
Key messages(s):
-Hot temperatures will continue through the weekend
-Rainfall probabilities increasing Friday through early next
 week

Hot temperatures will continue through the weekend with
increasing moisture and chances of showers and thunderstorms
Friday into early next week. Although there was some rain late
in the weekend and into early this week, the hot and dry
conditions over the past few days have generally minimized any
improvement from the rain. Moisture has begun increasing over
the area and scattered afternoon and evening thunderstorms
possible Friday mainly along and north of I-20. Increasing
coverage of afternoon and evening showers and thunderstorms are
expected to spread across the Midlands and CSRA Saturday through
much of next week. Temperatures will also be a concern with
afternoon highs in the upper 90s to around 100 which will push
heat index values to 110 Friday and between 105 and 110
Saturday.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for SCZ016-018-020>022-025>031-035-037-038-041-115-116-
     135>137.
GA...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for GAZ040-063>065-077.

&&

$$