832
FXUS63 KLSX 021711
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1211 PM CDT Tue Jun 2 2026

.KEY MESSAGES...

- Temperatures will be near normal in the upper 70s to low 80s
  with low humidity today and Wednesday. Dry weather continues on
  Thursday but temperatures edge up a few degrees into the low and
  mid 80s with increasing humidity.

- Warm weather continues Friday through next Monday with a chance
  for showers and thunderstorms through the period.


&&

.SHORT TERM... (Through Thursday)
Issued at 302 AM CDT Tue Jun 2 2026

A sprawling high pressure system will control our weather through
Thursday as it drifts from the Great Lakes today to the East Coast.
The high is currently pushing a back door cold front from the
northeast to the southwest through the forecast area, and much drier
air is filtering in behind it. Strong insolation due to high June
sun angle and a mostly clear sky will produce daytime highs around
80 today and Wednesday.  However light winds and good radiational
cooling conditions tonight and Wednesday night combined with the
much lower dew point air will allow temperatures to drop into the
50s.  The wind will turn back to the south Thursday which will help
temperatures warm a few degrees over today and Wednesday into the
mid 80s.  The southerly flow will also begin to bring higher
humidity back into the Mid Mississippi Valley which will set the
stage for more unsettled weather for the end of the week.

Carney

&&

.LONG TERM... (Friday through Monday)
Issued at 302 AM CDT Tue Jun 2 2026

Medium range guidance shows a mid-upper level short wave trough
moving from the Plains into the Midwest Thursday night into Friday.
This triggers convection over eastern Kansas into western Missouri
on Friday with precip moving into central and northeast Missouri
during the afternoon. Deterministic guidance shows decreasing
instability across east central and southeast Missouri into
southwest and south central Illinois.  This is backed up by the LREF
mean surface based and most unstable CAPE forecasts, so convection
looks likely to run out of steam before reaching these areas Friday
afternoon. However, persistent southerly flow will continue to bring
richer moisture into the Mississippi Valley Friday night into
Saturday morning which will allow convection to spread across the
area. Models diverge Saturday night into Monday as the GFS winds up
a closed upper level low over the Great Lakes while the ECMWF
develops a strong ridge in the same location.  In terms of sensible
weather, the GFS would push a weak surface cold front through the
Mid Mississippi Valley Saturday night which leads to a slightly
cooler but much drier Sunday and Monday.  The ECMWF keeps us in
deep, warm and moist southerly flow.  It also shows a mid-upper
level short wave moving slowly northeast through the central Plains
which continues to produce precip through Monday.  The majority of
the LREF members keep precipitation chances going through Monday,
which makes the deterministic GFS look like the outlier.  The wetter
LREF forecast also jives with the NBM forecast, so I don`t see any
reason to deviate and lower PoPs at this time.   Highs through the
period hover in the mid to upper 80s with lows in the mid to upper
60s.  With that in mind, max Ts will be highly dependent on
convective trends each day.

Carney

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1209 PM CDT Tue Jun 2 2026

High pressure over the Great Lakes will maintain dry, easterly
flow through the period. There is high confidence in VFR
conditions persisting through Wednesday afternoon.

Maples

&&

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

$$

WFO LSX