143
FXUS63 KLSX 161922
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
222 PM CDT Tue Jul 16 2024

.KEY MESSAGES...

- Additional thunderstorms are possible this afternoon and evening
  mainly across southern Missouri and southern Illinois. Heavy
  rainfall producing flash flooding is the main threat, although
  some stronger storms could produce gusty winds.

- An extended period of cooler than normal mid-summer temperatures
  is expected to last through the end of the week with
  predominantly dry conditions expected as well.


&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 221 PM CDT Tue Jul 16 2024

A slow moving cold front has entered the forecast area, although
it is being somewhat masked by widespread stratiform rain in the
wake of earlier convection. Extensive cloud cover associated with
this rainfall has led to much cooler temperatures and a locally
stable environment which has reduced the threat for additional
thunderstorms this afternoon. However, the southern portion of
Missouri did not get as much rain or cloud cover today, with hot
and humid conditions leading to robust instability. Additional
thunderstorms are expected to form here along outflow boundaries
as well as associated with a remnant MCV drifting east out of
southeast Kansas. Much of this renewed thunderstorm development
will stay south of our forecast area, but the southern portions of
our area may be impacted by rain from this. Considering very high
PWATs in excess of 2 inches and the potential for training
convection, the Flash Flood Watch remains in effect for southern
portions of the area. However, the central and northern portions
of the Watch have been canceled as additional flash flooding is no
longer expected in those areas.

Thunderstorms which form this evening are expected to move off to
the southeast during the evening, likely exiting our forecast area
entirely by around midnight. This also shifts the area for renewed
development on Wednesday further south as well, and POPs for
Wednesday have been duly adjusted downward. The temperature
forecast has actually come up a bit, though, as we should see
more sunshine. Still, though, below normal mid-summer temperatures
mainly in the mid 80s are expected.

Kimble

&&

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 221 PM CDT Tue Jul 16 2024

Western ridging and eastern troughing keeps our area in a north to
northwesterly flow aloft and relatively cool surface high pressure
in place near the area. This will bring dry and below normal
temperatures through the end of the week. Indications are we could
see some shortwave troughs dropping southeast through the upper
level flow late in the week which bring rain chances back in the
forecast, but the overall upper pattern remains similar with below
normal temperatures.

Kimble

&&

.AVIATION... (For the 18z TAFs through 18Z Wednesday Morning)
Issued at 221 PM CDT Tue Jul 16 2024

Lingering stratiform rain with occasional embedded thunder
continues for the next few hours across the St Louis metro area.
But a general drying trend is expected, though some MVFR ceilings
may develop. The next round of thunderstorms is expected to stay
well to the south. If there are breaks in the clouds overnight,
local fog could develop especially in areas with a lot of standing
water. Winds become northerly tonight into tomorrow with VFR
likely returning area wide by mid morning Wednesday.

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through Wednesday morning for Crawford MO-Iron MO-
     Madison MO-Reynolds MO-Saint Francois MO-Sainte Genevieve
     MO-Washington MO.

IL...Flood Watch through Wednesday morning for Randolph IL-Washington
     IL.

&&

$$

WFO LSX