124
FXUS62 KCAE 051721
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
121 PM EDT Fri Jul 5 2024

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

Ridge axis remains across the region this afternoon, yielding
intense heat and humidity across the forecast area. Temperatures
are already in the upper 90s, with dewpoints in the mid to upper
70s. This is creating dangerous heat, and the Heat Advisory
remains in place until this evening. Instability has been
quicker to develop this afternoon, though, and agitate cumulus
is actually being noted across the Midlands as of this writing.
Some isolated to scattered showers and storms may develop here,
but better chances for storms are possible this evening. A
line broken line of thunderstorms (not severe in nature at this
time) is more concise and a bit faster than most CAMs in the
HREF had it across N GA and E TN. This will likely continue to
move eastward given the uncapped, unstable air ahead of it in
SC. I see no reason why this wouldn`t at least bring some
showers or storms to the western Midlands and CSRA this evening,
and this idea is supported by some CAMs despite them being a bit
slower with it. So have bumped up PoPs in general this
afternoon, with rain being the only hope of some relief from the
heat. Highs should end up between 99F and 102F most places. Some
isolated showers/storms may hang around into the overnight
hours, but whatever is left should weaken tonight. Given high
dewpoints and warm airmass, its unlikely that lows fall much
lower than the mid 70s tonight, with some (especially in urban
areas) potentially remaining near 80F overnight.

&&

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

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

Main upper trough axis will continue across the middle of the
country through the weekend, with some upper ridging still being
indicated across the forecast area. At the surface, a decaying
surface front will move into the cwa, which will at least
enhance lift somewhat. Add in high pwat values above the 2 inch
mark, and some instability by the afternoon each day, and we
should see scattered to possibly numerous showers and
thunderstorms developing bot Saturday and Sunday. High pwat
readings and potentially slower moving storms could lead to some
heavier rainfall at times.

Another day of higher heat indices are expected to be high over
the weekend. Afternoon highs in the middle 90s,and a good amount
of moisture, will lead to heat index readings above 105 to 110
for a period Saturday. Can not rule out another Heat Advisory
through the afternoon, but will wait until the current Advisory
expires this evening before possibly pulling the trigger on
that. There is still some uncertainty as to exact heat index
values, mainly due to when convection starts and how much cloud
cover gets created by that. Earlier convection and clouds would
keep slightly cooler readings, while later convection and more
sunshine will more than likely cause readings to rise to
advisory criteria. Sunday will be slightly cooler with more
clouds, and this will keep heat index readings between 95 to 105
degrees.

&&

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

- After Monday, heat indices climb back over 100 degrees.
- Daily diurnal convection expected.

We get back into a slightly more typical Summertime pattern
through the week. Pwat values remaining relatively high, at or
above 2 inches, with continued upper ridge just off the east of
the region across the western Atlantic. The main upper trough
axis continues to be west of the area, with stronger dynamics
deflecting further off to the north through the period. With
plenty of moisture, and afternoon highs forecast in the low to
mid 90s each day, much of the guidance shows high likelihood for
diurnal showers and thunderstorms. With the high pwat values,
any slow moving storms could produce periods of heavy rainfall.
In addition, can not rule out an isolated severe thunderstorm
threat.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions expected through the TAF period.

Cumulus has developed in earnest this afternoon as the surface
has heated up quickly. Some of this has yielded towering CU and
even some showers near CAE/CUB. This will likely remain
isolated enough to not include at either site. Better chances
for showers/storms will arrive at AGS/DNL this afternoon, with
VCSH looking reasonable for a couple of hours there.
Vis restrictions are probable if a shower/storm passes directly
over a site given how much moisture is in the atmosphere;
otherwise, restrictions are not expected at all through the
period. Strong low-level jet should prevent stratus or fog
tonight. Winds are generally expected to be out of the south or
southwest between 5 and 10 knots. Showers/thunderstorms are
expected at all TAF sites tomorrow but should be after 18z.

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

&&

.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.

&&

$$