Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 152321
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
621 PM CDT Fri Mar 15 2024

.KEY MESSAGES...

-Dry weather is expected through the weekend into early next week.

-Temperatures will be variable through the period with above
 normal highs on Saturday, dropping to below normal behind a cold
 front Sunday and Monday. Above normal temperatures will return by
 mid-week.


&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 235 PM CDT Fri Mar 15 2024

A ridge of high pressure is overhead, so with clear skies and light
winds temperatures will dip down into the upper 30s to low 40s
tonight.

On Saturday, the surface ridge will weaken with winds backing to the
west to southwest ahead of a cold front. This front is associated
with a strong shortwave over northern Saskatchewan and Manitoba that
will drop southeast into the Great Lakes Region later in the day on
Saturday. Latest forecast soundings show strong mixing up to near 800mb
with winds gusting up to 30kts at times. The combination of a
tightening pressure gradient, deep mixing and plenty of sunshine
will allow temperatures to warm up into the 60s on Saturday.

In the meantime, the shortwave dropping into the Great Lakes region
will try to phase with a closed low over the Desert Southwest. This
will help drive the cold front south through the forecast area
Saturday night. However, with very weak low-level convergence along
it and the better mid/upper level forcing for ascent residing across
the Great Lakes it will be a dry frontal passage, but will see
increasing mid and high clouds. The clouds will keep temperatures
from dropping too much, so expect lows in the low 30s to low 40s.

Byrd
&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 235 PM CDT Fri Mar 15 2024

On Sunday, a majority of the deterministic and ensemble model
runs agree that a strong secondary shortwave will dive south
through the region on the back side of the cold front. This will
usher in even colder air. During the day on Sunday highs will only
be in the mid 40s to upper 50s with gusty northwest winds up to
30kts at times. Latest LREF ensembles have a high probability that
lows will be below freezing (80-100%) across the entire forecast
area, with a hard freeze likely, 28 degrees or colder (60-80%
probability) for a majority of the forecast area, except for the
St. Louis metro.

On Monday as the upper level trough digs over the eastern half of
the CONUS, upper level ridge builds over the Western CONUS. So the
forecast area remains in the transition zone with northwest flow
aloft. So the coldest day this week will be Monday with highs only
in the 40s. Then as the upper trough moves further east, weak upper
level ridging begins to moves in allowing temperatures to moderate
through the rest of the work week. Expect above normal temperatures
in the 60s Tuesday through Thursday. Otherwise, the next chance for
rain will be Wednesday night through Friday. However, the latest
LREF cluster analysis has timing, strength and location differences
as the system lifts out of the Desert Southwest towards the region.
Therefore stuck with the latest NBM solution with the best chances
of showers and storms Thursday afternoon through Thursday night at
this time.

Byrd

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 618 PM CDT Fri Mar 15 2024

VFR flight conditions are expected through the forecast period.
Surface winds will diminish after sunset and slowly back to the
southwest through the night. Winds will then increase and become
quite gusty from the west by mid-late Saturday morning.

Glass

&&

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

$$

WFO LSX


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