540
FXUS63 KLSX 070336
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1036 PM CDT Wed May 6 2026

.KEY MESSAGES...

- Dry weather with below normal temperatures are expected tonight
  and Thursday.

- Showers and thunderstorms return to the forecast Friday-Friday
  night, and again Saturday night-Sunday morning.

- Temperatures warm up Friday through Saturday, but another cold
  front cools the area off again Sunday and Monday.


&&

.SHORT TERM...  (Through Late Thursday Night)
Issued at 206 PM CDT Wed May 6 2026

Dry weather is expected tonight through Thursday night as high
pressure builds from the Great Plains across the Mississippi Valley.
Guidance is forecasting low temperatures in the low to mid 40s with
some scattered upper 30s in sheltered spots, and this agrees well
with upstream observation from this morning.  Some patchy frost
could develop in the coldest spots late tonight, although some mid
and high clouds may make radiational cooling conditions less than
ideal so have left mention of frost out of the forecast for now. The
ridge axis moves south of Missouri and Illinois on Thursday which
turns winds back to the southwest.  This along with strong May
sunshine will help temperatures rebound up to around 15 degrees for
highs in the mid to upper 60s across the area.  Southerly flow
continues Thursday night, which will produce low temperatures closer
to normal in the low to mid 40s Friday morning.

Carney

&&

.LONG TERM...  (Friday through Next Wednesday)
Issued at 206 PM CDT Wed May 6 2026

The weather pattern over North America for Thursday through next
Tuesday will be dominated by an upper level low over Hudson Bay, and
semi-persistent long wave ridging over the West Coast.  This results
in persistent west to northwest flow aloft over the Mid Mississippi
Valley through the period.  A few short waves will move across the
area embedded in the long wave flow, at least two of which will have
the potential to produce more rain.  The first wave on Thursday
pushes the cold front through the Lower Mississippi Valley into
the northern Gulf.  Forecast soundings show a fairly dry atmosphere
above us, so the wave should pass with little sensible weather at
the surface.  The wave will help to move the cool surface high from
the eastern Plains into the Lower Mississippi Valley by late
Thursday which will keep our afternoon highs seasonably cool in the
mid 60s.

Low level flow swings back to the southwest as the surface high
moves across the Appalachians Thursday night.  This brings some
moisture back into our region for the next short wave on Friday to
work with.  Models generate some light QPF across the area as the
wave moves through Friday afternoon, and CAPE values rise to around
1000 J/Kg ahead of the surface reflection of the wave.  This will
likely result in scattered showers and a few thunderstorms in the
afternoon.  Forecast soundings show weak lapse rates and skinny CAPE
profiles which are not conducive to strong updrafts and severe
storms.  Temperatures show a steady rise Friday into Saturday as low
level flow mostly prevails from the southwest, even after the
trough passes on Friday night.

A third, stronger short wave will dig into the Great Plains Saturday
night into Sunday morning.  This wave will push a cold front through
the area on Sunday and there should be plenty of moisture to produce
precipitation with this system.  The LREF continues to show some
variance with the timing and amplitude of the wave, and therefore
the speed of the front and strength of cold air advection behind it.
 Temperature IQRs have narrowed on this morning`s 12Z run of the
LREF, but are still 6-8 degrees both Sunday and Monday.
Deterministic NBM highs both days are in the low to mid 70s which is
around the 75th percentile for the LREF.  Another short wave is
forecast to move into the Great Plains on Tuesday with another
chance for precipitation.  However the LREF cluster analysis is
showing a lot of variance in is position, so confidence in another
round of rain is low at this time.

Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1033 PM CDT Wed May 6 2026

Dry and VFR conditions are expected through the period. Light and
variable winds are expected to increase out of the southwest
around 13Z on Thursday morning and increase into the the 10-12
knot range with higher gusts during the afternoon.

Britt

&&

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

$$

WFO LSX