188
FXUS63 KLSX 221733
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1233 PM CDT Sun Sep 22 2024

.KEY MESSAGES...

-There will continue to be chances for showers and thunderstorms
 through Tuesday.

-Isolated severe storms are possible over southeast Missouri and southwest
 Illinois this afternoon and early this evening. The primary
 threat with the strongest storms will be damaging winds.

-Temperatures will cool down behind a cold front today with below
 normal highs on Monday and Tuesday.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 403 AM CDT Sun Sep 22 2024

Initial round of showers and thunderstorms is moving through the CWA
this morning ahead of the cold front in a band of strong low level
moisture convergence.  This first round will eventually exit to the
east by mid-morning as the low level jet veers and weakens. There
will continue to be lesser chances (30-50%) for showers and
thunderstorms this afternoon into this evening as the cold front
that is currently over southeastern Iowa and northwest Missouri will
move southeast across the CWA.  There still remains the possibility
for one or two storms to produce damaging microbursts over southeast
Missouri into southern Illinois this afternoon and early this evening
given MLCAPES around 1500 J/kg and deep layer shear around 30 knots.
There will be some potential for locally heavy rainfall given that
PWATS will be in the 1.6-2" range today, especially where any storms
can train for very long.

The chance for showers and thunderstorms will begin to increase
again late tonight into Monday, particularly over the southern half
of the CWA.  Lift will increase across Missouri and Illinois as the
HREF is showing an upper trough moving into the area from the west.
Have kept higher PoPs (60-80%) over the southern half of the CWA
where the stronger forcing and the best moisture transport will move
into the area late tonight into tomorrow afternoon.

There will be quite a range in highs today with the front and rain,
ranging from near 70 over the north to the middle 80s in the south.
Highs tomorrow will be below normal across the CWA with cold air
advection behind the front, the clouds, and rain chances.

Britt

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 403 AM CDT Sun Sep 22 2024

There is decent agreement amongst the medium range models that upper
trough will drop down into the Midwest behind Monday`s trough which
will keep showers and thunderstorms going over the area Monday night
into Tuesday.   Some solutions show an upper low cutting off over
the Midwest into late week which would keep a chance (20-30%) of
showers going over the CWA Thursday into Saturday.

Temperatures will still be below normal on Tuesday, but will climb
back to near normal the rest of the week.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1159 AM CDT Sun Sep 22 2024

A mixed IFR to VFR ceiling persists over the area with gradual
improvements expected at the terminals to high MVFR or even VFR
flight conditions. Ceilings are expected to drop back down to MVFR
or even IFR conditions as early as the evening hours as daytime
mixes diminishes. Confidence is highest that conditions will
degrade to MVFR with a round of rain that is expected tomorrow
morning. Guidance points to IFR conditions building in overnight,
largely tied to the previously mentioned rain, however confidence
is not yet high enough to include a mention in the TAFs for the
moment.

Speaking of rain, showers are lingering across the area this
afternoon but should gradually clear ahead of shower and
thunderstorm chances mainly south of I-70 and the mid-Missouri and
St. Louis metro terminals. The next best chance (50-60%) for rain
will push into the area tomorrow morning from the southwest,
impacting the mid- Missouri and St. Louis metro terminals.

Southwesterly winds will become northwesterly to northerly over
the afternoon and into early evening as a cold front slides
through the forecast area. Wind speeds will stay largely below 10
kts.


Delia

&&

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

$$

WFO LSX