165
FXUS63 KLSX 032324
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
624 PM CDT Mon Jun 3 2024

.KEY MESSAGES...

- Several rounds of showers and thunderstorms are expected through early
  Wednesday. Isolated severe storms are possible through this
  evening and again on Tuesday, capable of producing large hail
  and damaging winds. Locally heavy rainfall is also possible.

- Dry weather is expected mid-late week followed by a chance (20-
  40%) of showers and thunderstorms this weekend.

- Temperatures are expected to be at or just below normal through
  early next week.


&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 346 PM CDT Mon Jun 3 2024

Scattered showers and thunderstorms have developed across central
and southeast Missouri along outflow boundaries that moved into the
area.  The atmosphere is very unstable over the CWA right now with
MLCAPES between 1000-2000 J/kg with no CIN which the RAP shows
holding on through sunset.  The latest water vapor imagery is
showing a trough over the eastern Plains that will move slowly east
into Missouri tonight.  This trough is far enough west that there is
little ascent or low layer or deep layer shear for organized
thunderstorms tonight. As such, should only see isolated
instances of strong-severe hail and wind through mid evening.
There may also be some locally heavy rainfall with any training
thunderstorms given the high PWATS and warm cloud depths.

I have lowered PoPs late this evening into the overnight hours as
CAMS have backed off on the coverage of showers and thunderstorms
overnight.  Still expect an uptick in scattered showers and
thunderstorms again on Tuesday as the HREF is bringing the
aforementioned trough across the area.  It is possible that a MCV
from overnight Plains activity will move across the area sparking
additional convection.  The CAPE/shear parameter space tomorrow
afternoon into tomorrow evening will once again support isolated
severe storms with locally heavy rainfall. The coverage of showers
and thunderstorms will become more widespread later in the evening
and overnight as the NAM/GFS is showing a upper trough dropping
southeast into Missouri and Illinois with an attendant cold front.

Britt

&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 346 PM CDT Mon Jun 3 2024

There is general agreement between the deterministic models and the
LREF that the upper flow will stay northwesterly late week through
the upcoming weekend.  Wednesday through Friday still looks dry as a
large surface high will move southeast across the Midwest with very
few of the ensemble members producing precipitation over the area
during this timeframe. There is more uncertainty as we go into
the weekend as each of the models are showing slight differences
in the timing and strength of two shortwaves on Saturday and
Sunday which will determine the placement and amount of the QPF.
There is an increase in LREF ensemble members producing rain
(20-40%) with these two shortwaves over the weekend. There are
lower chances as we go into next Monday with the model consensus
showing a surface high moving back into the area.

Temperatures will not stray too far from early-mid June normals as
850mb temperatures will stay in the 10-15C range.  The NBM IQR is
around 5 degrees, though it does increase by early next week behind
a cold front.

Britt

&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 611 PM CDT Mon Jun 3 2024

Scattered and thunderstorms will affect the terminals in the first
1-2 hours, then mainly dry and VFR conditions are expected tonight.
Another round of scattered showers and thunderstorms is expected
late Tuesday morning and afternoon. Any thunderstorm has the
potential to reduce ceilings and visibilities to MVFR (possible
IFR) conditions in brief downpours with gusty winds. Winds will
remain out of the south around 10 knots outside of thunderstorms.

Britt

&&

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

$$

WFO LSX