Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 092336
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
536 PM CST Sat Dec 9 2017

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 315 PM CST Sat Dec 9 2017

Clouds have begun to break up over parts of the area, and will
continue to clear out over eastern Missouri and Illinois during the
late afternoon and evening hours.  This will occur as the upper
trough currently extending from the Great Lakes into the Ohio Valley
will move east tonight.  At the surface, the current northwest winds
will back out of the southwest overnight which should cause
temperatures to become nearly steady overnight.  Lows will fall into
the 20s tonight because of the cool temperatures today, but won`t
fall as much because of the southwesterly winds overnight.  Highs
tomorrow will climb into the 50s ahead of a cold front that will
move across the area.  Mostly sunny skies and southwest winds ahead
of the cold front will cause temperatures to climb above normal.

Britt

.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 315 PM CST Sat Dec 9 2017

Upper pattern promises little prospect for significant precipitation
for next week. Both the GFS/ECMWF is showing an amplified pattern
with MO/IL lying beneath northwesterly flow aloft. Currently the
global models are showing shortwave troughs with attendant cold
fronts moving through the Midwest on Monday and again Wednesday
and Wednesday night. Moisture will be limited with both systems,
so only have slight chances for rain/snow at this time.

Temperatures will warm up above normal again on Monday, but fall
back closer to normal the rest of the week.  The GEFS ensemble does
show a wide spread in temperatures over the week which lowers the
overall confidence in the temperature forecast this week under the
northwesterly flow.

Britt

&&

.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 532 PM CST Sat Dec 9 2017

VFR flight conditions will prevail through the forecast period. A
surface ridge currently centered through western MO will flatten
and progress through the area tonight. This will result in backing
surface winds to more southwesterly by Sunday morning. Surface
winds will then increase on Sunday morning and shift to the
northwest with the passage of a surface trof. Clouds should be
limited to several waves of high clouds.

SPECIFICS FOR KSTL:

VFR flight conditions will prevail through the forecast period.
Surface winds will weaken and back tonight to more southwesterly
by Sunday morning. Surface winds will then increase on Sunday
morning, and shift to the northwest with the passage of a surface
trof in the afternoon. Clouds should be limited to several waves
of high clouds.

Glass

&&

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

$$

WFO LSX



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