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000
FXUS63 KLSX 152315
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
615 PM CDT Mon Apr 15 2024

.KEY MESSAGES...

- Scattered thunderstorms (up to a 40% chance) remain possible
  through this evening. One or two of these storms could become
  severe, with quarter size hail and gusty winds being the main
  threats.

- Severe thunderstorms look likely on Tuesday during the afternoon
  and early evening hours, particularly across central and
  northeast Missouri into west central Illinois. Large hail,
  damaging winds, and tornadoes are all possible, with the area
  mentioned above at risk for very large hail and a strong
  tornado.


&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 357 PM CDT Mon Apr 15 2024

Latest surface analysis is showing a front extending from just north of
Kansas City to near St. Louis to north Evansville.  Latest satellite
imagery is showing a cumulus field south of this front where the SPC
mesoanalysis is showing MLCAPES of 1500-2000+ J/kg.  The latest
HRRR/RAP is showing  the front remaining in the place this evening with
a isolated-scattered thunderstorms developing along the front as the
cap breaks between 23-02Z.  One or two of these storms may become
severe given the amount of instability and deep layer shear around 30
knots. Then the HRRR is showing any storms moving out of the area by
late this evening with a chance of showers overnight.

More active weather will occur with two waves of severe weather likely
on Tuesday.  The aforementioned front will move north of the area early
in the day in response to a deep surface low moving east across
Nebraska.  This will put us in the open warm sector with the first
round forced by a combination of mid level lead shortwave paired with a
band of low level moisture advection. The HRRR has been consistent
in showing a north-south band of showers and thunderstorms across
the CWA between 12-5 pm. MLCAPES will be around 1000 J/kg ahead of
this band with deep layer shear of 50-60kts indicating that
supercells and organized mutlicells will be possible within this
band capable of producing large hail, damaging winds, and a
tornado or two. The second band will likely occur between 4-8 pm
ahead of a weak vort lobe paired with a dry line. The HRRR have
been showing discrete cells developing ahead of the dryline where
there are forecast hodographs with large curvature in the 0-3km
layer and 0-1km shear of 35 knots. While there are questions about
whether there will be enough time to destabilize behind the first
wave, the NAM/GFS is showing MLCAPES of 1000-1500 J/kg in the
area that these storm develop in which does support the SPC
Enhanced risk and the potential for very large hail and a strong
tornado with these storms. This line will likely move out of the
CWA by mid-late evening leaving the overnight hours dry.

Britt
&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 357 PM CDT Mon Apr 15 2024

Mainly dry weather is expected on Wednesday and Wednesday night before
a northern stream system brings a cold front through the area.  The
LREF supports likely PoPs late Thursday into Thursday night.  Showers
and thunderstorms will linger over the area into Saturday before Sunday
will be dry.  Temperatures will remain above normal into Thursday
before falling below normal behind the cold front on Thursday.

Britt
&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 615 PM CDT Mon Apr 15 2024

As the warm front slowly lifts north tonight, isolated showers
and storms possible, especially over central Missouri through
02z-03z and over KUIN between 04z and 08z Tuesday, so have
vicinity thunderstorms in the TAFs. Otherwise, better chances will
be during the afternoon hours on Tuesday, after 15z-19z, for all
TAF sites.

As for winds, they will remain east to southeast overnight, then
veer to the south and pickup Tuesday morning with gusts up to 35kts
at times.

Byrd
&&

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

$$
WFO LSX