858
FXUS63 KLSX 180335
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1035 PM CDT Mon Jun 17 2024

.KEY MESSAGES...

- Isolated to scattered thunderstorms can be expected both late
  this afternoon and again on Tuesday afternoon over parts of the
  area.  Brief downpours are possible with the strongest storms.

- High temperatures are expected to remain mainly in the 90s
  through the upcoming weekend.


&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 213 PM CDT Mon Jun 17 2024

Latest radar imagery is showing a complex of showers and
thunderstorms moving north across southeast Missouri ahead of a vort
max moving north around the back of the subtropical high currently
centered over the Carolinas.  This complex will will likely affect
the southeastern counties late this afternoon with some brief
downpours given that PWATS are around 1.8" before it begins to
diminish by early this evening. There will another chance (20-30%)
for isolated showers and thunderstorms late Tuesday morning into
Tuesday afternoon as another vort max moves north across Missouri
and Illinois in the deep moisture feed.

Temperatures so far this afternoon have climbed into the upper 80s
to the mid 90s with a few locations having heat indices over 100
degrees.  Highs tomorrow are expected to be a degree or two cooler
with a few more clouds and slightly more coverage of showers and
storms.  Lows the next two nights will stay in the low to mid 70s.

Britt

&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 213 PM CDT Mon Jun 17 2024

The overall forecast remains on track as the global models and the
LREF continue to show that the upper high over the East Coast will
expand back into the central CONUS as soon as Wednesday which will
push the westerlies north of the area through Saturday.  This will
now confine the chance of showers and thunderstorms on Wednesday to
just the northwest third of the CWA and keep the CWA dry through
Saturday.   There continues to be some agreement that a trough and
an attendant cold front will move across the Midwest late in the
weekend with 30-60% of the ensemble members showing a chance of rain
with the passage of this system.   There remains some uncertainty
with the timing of this system between the deterministic guidance,
but the LREF is showing northwest flow over the area by next Monday
with just slight (20%) chances for showers and thunderstorms.

Temperatures are expected to climb into the middle to upper 90s late
this week as the upper high builds back over the area. Dewpoints are
expected to remain in the 60s which are forecast to keep maximum
afternoon heat indices near 100 degrees. Temperatures will drop back
down just a bit on Sunday and next Monday with the frontal passage.
This matches up well with the NBM IQR which is only showing a 5
degree spread at St. Louis through Saturday under the upper high,
but then increases to 8-9 degrees with the passage of the trough
early next week.

Britt

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1035 PM CDT Mon Jun 17 2024

SSE winds continue under VFR sky conditions. Winds pick up a bit
earlier Tuesday morning than they have the previous few days,
gusting to 20 or 25KT during the peak of the day. There will
probably be some isolated thunderstorms around during the
afternoon, but there`s not a clear indication of where they will
form and confidence is too low to mention in any TAF at this time.

Kimble

&&

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

$$

WFO LSX