215
FXUS63 KLSX 310920
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
420 AM CDT Sun May 31 2026

.KEY MESSAGES...

- There will be several chances of showers and thunderstorms through
  tomorrow with a low chance of severe thunderstorms capable of
  producing large hail and damaging winds.

- Dry weather is forecast Tuesday through Thursday along with near
  normal temperatures.

&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 418 AM CDT Sun May 31 2026

Patchy fog has developed over parts of the area like yesterday
morning with varying visibilities.  With light winds and yesterday`s
rainfall, visibilities have fallen as low as 1/4 mile so far at SUS
and CPS, but have since climbed back up to 10 miles.  With the
clouds overhead and the relatively short night, I suspect any dense
fog will stay patchy the rest of the night.

There will the potential for several rounds of showers and
thunderstorms to move across parts of the CWA through Monday.  There
remains a strong CAPE gradient that is expected to remain in place
from west to east in addition to the persistent low level
convergence axis.  Showers and thunderstorms currently over western
Missouri are slowly moving east, and may move into central Missouri
early this morning.  An upper trough over the central Plains will
lift northeast this morning and supply decent ascent over the area
this afternoon.  The CAMS are showing an increase in convection over
the area by mid afternoon into this evening, though they are
inconsistent with their timing and location.  This is likely because
there will be an upper ridge building over Missouri and Illinois
today causing weak steering currents. The CAMS are also showing
some redevelopment of the thunderstorms over northern Missouri
this evening that will move into the CWA overnight. Both of these
rounds will have some potential of isolated severe thunderstorms
in the SPC marginal risk with up to 1" hail and 60 mph winds,
though the coverages an severity of storms will be dependent on
the previous rounds of storms. There will also be the potential
for heavy rainfall to produce localized flooding, particularly
over central and southeast Missouri where PWATS will be around
1.8" with warm cloud depths over 10k feet.

The CAMS are showing the second round of convection exiting the
CWA by 12Z on Monday. Both the RAP/GFS is showing a front
lingering back across central and southeast Missouri during the
day with sufficient CAP/shear to bring the risk of an isolated
strong to severe thunderstorm.


Britt

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 418 AM CDT Sun May 31 2026

Model guidance is consistent showing an upper high moving south
across Midwest Tuesday into Thursday resulting in dry weather across
the CWA during this period.  The chance for showers and
thunderstorms will return beginning on Thursday night and continues
into Saturday when moisture return will increase ahead of upper low
over the Plains.  The LREF is showing 40-60% of its members
producing rain over the CWA by Saturday.

WHile temperatures may cool down to around 80 on Tuesday and
Wednesday, highs are forecast to be mainly in 80s this week as they
climb back into the upper 80s by Friday and Saturday.

Britt

&&

.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1037 PM CDT Sat May 30 2026

Fog is the main concern through the very early morning hours;
mainly at KSUS and KCPS. Visibilities are expected to bounce
around, with the worst impacts expected to be more consistent just
before sunrise. Our attention then turns to what will be a
decaying line of showers and thunderstorms moving eastward into
the region. These showers and storms have the greatest potential
for impacting KCOU and KJEF, with confidence very low in impacts
further east at KUIN, KSUS, KSTL, and KCPS. There is a low to
medium chance for at least one more round of showers and
thunderstorms during the afternoon and/or evening, with any of the
local terminals having the potential of seeing impacts. Timing and
placement of this second round is very uncertain, and will be left
out the TAFs for now.

Elmore

&&

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

$$

WFO LSX