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000
FXUS63 KLSX 191124
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
624 AM CDT Fri Apr 19 2024

.KEY MESSAGES...

- Seasonably cool weather is forecast through the weekend, with
  frost potential both Saturday and Sunday nights.

- Dry weather expected until next Tuesday.


&&

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 314 AM CDT Fri Apr 19 2024

Surface ridge will build in across the region today with strong low
level cold air advection, thus highs will be 10 to 20 degrees lower
than yesterday, in the upper 50s to upper 60s. In the meantime with
zonal flow aloft and latest forecast soundings indicating plenty of
mid and upper level moisture, will see mid and high clouds stream
east across the area over the next 24 to 48 hours.

For tonight, even with lows dipping down into the mid to upper 30s,
the clouds and surface winds around 10 mph will keep frost from
developing. Then on Saturday, even colder air will advect in with
highs only in the low 50s to mid 60s, around 10 degrees below normal.

Byrd
&&

.LONG TERM...  (Saturday Night through Thursday)
Issued at 314 AM CDT Fri Apr 19 2024

(Saturday Night - Sunday Night)

Surface ridge will remain overhead for the rest of the weekend, so
temperatures will stay a bit below normal. As for the formation of
any frost Saturday night and Sunday night, despite light and
variable winds both nights, clouds Saturday night (mainly across
portions of southeast Missouri and southwestern Illinois) will limit
frost formation to central/northeast Missouri and west central
Illinois. Then on Sunday night despite clear skies, the surface
ridge begins to slide off to the southeast with winds backing to the
west to southwest. Thus temperatures will be a bit warmer with just
some patchy frost expected at this time.


(Monday - Next Thursday)

With southerly surface flow returning to the region early next week,
temperatures will moderate with highs near normal once again. In the
meantime, an upper level shortwave over the western provinces of
Canada will begin to slide southeast into the Great Lakes region
with an associated cold front. However, the latest deterministic
models have differences in timing, strength and location of the
system. Therefore, stayed with the latest NBM solution which has
the front moving into the region on Tuesday/Tuesday night with the
best chances of showers and storms during the day. As for any
severe storms, despite strong 0 to 6km bulk shear (40-50kts),
instability is very limited (MU CAPE around 400 J/kg), thus
confidence is low for any severe weather at this time. Otherwise,
dry and slightly cooler weather is expected for mid week.

Byrd
&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 622 AM CDT Fri Apr 19 2024

Dry, VFR flight conditions through the forecast period. Otherwise,
north to northwest winds becoming light and variable after 01z-02z
Saturday.

Byrd
&&

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

$$
WFO LSX