800
FXUS63 KLSX 060750
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
250 AM CDT Wed May 6 2026

.KEY MESSAGES...

- Cooler and drier weather is forecast through Friday ahead of a weekend
  warm-up.

- There will be multiple chances for showers and thunderstorms
  from Friday night through Sunday. No severe weather is expected.


&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 249 AM CDT Wed May 6 2026

Cool and dry weather is forecast today and tomorrow behind
yesterday`s cold front. As cold air advection and persistent cloud
cover continue, temperatures today will only reach the 55 to 60
degree range for most. Clouds will thin overnight, and north winds
will become light and variable areawide. The potential for
radiational cooling paired with the cool start to the night will
allow temperatures to drop into the upper 30s and low-40s. Patchy
frost may occur (<20% chance) in valleys and sheltered areas, but
that would be the greatest extent of any frost development if it
happens at all. A slight boost in high temperatures is expected on
Thursday as skies remain mostly clear and cold air advection
continues to weaken. Highs in the 60s are forecast everywhere.
Mostly dry conditions are expected during this timeframe due to dry
post-frontal air and a lack of potent lift and forcing mechanisms.

Jaja

&&

.LONG TERM...  (Thursday Night through Tuesday)
Issued at 249 AM CDT Wed May 6 2026

Multiple mid-level shortwaves are forecast to pass through the Mid-
Mississippi Valley between Friday and Sunday. Renewed Gulf moisture
along southwesterly flow will allow Friday`s shortwave to impact our
sensible weather by way of showers and thunderstorms. Despite LREF
effective shear values of 40 to 50 kts on Friday, the grand ensemble
only shows SBCAPE reaching 400 to 500 J/kg. Model soundings show an
unimpressive atmospheric profile as well. Long, skinny CAPE is not
favorable for hardy, long-lasting updrafts and unidirectional shear
does not bode well for tornadogenesis.

The strongest shortwave will arrive Sunday morning and will drive a
potent cold front through the forecast area. Showers and
thunderstorms are expected yet again with this system, again with
minimal severe potential. The greatest potential for thunderstorms
would likely be Sunday afternoon in the areas ahead of the cold
front, but a modeled large capping inversion would mitigate this.


The cold front will have an impact on the temperature forecast
between early and late this weekend. A warm-up beginning Friday will
peak on Saturday with highs reaching the 70s and 80s. Sunday`s cold
front will knock highs back into the 60s and 70s. Exact values are
still uncertain given differences in the timing of the frontal
passage. This is reflected in NBM IQR high temperature spreads of
about 10 degrees across the region. After another cool day Monday, a
warm-up is expected to carry us into the middle of next week.

Jaja

&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1157 PM CDT Tue May 5 2026

Rain will continue to shut off late tonight with dry weather
expected before sunrise. MVFR to IFR clouds will continue to shunt
south tonight, and the entire forecast area should be VFR by early
afternoon. Winds will remain mostly at or under 5 kts through the
TAF period. The prevailing wind will be from the north.

Jaja

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX