Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 012320

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
620 PM CDT Wed Apr 1 2020

.SHORT TERM...  (Through Late Thursday Night)
Issued at 353 PM CDT Wed Apr 1 2020

Surface ridge continues to move east of the area and winds are
beginning to pick up out of the southeast in its wake. Latest
satellite imagery is showing high clouds streaming into the
region. This increase in upper clouds will continue as upper ridge
is forecast to pass through the region this evening. This will
occur at the same time the upper flow transitions to the
southwest as an upper trough moves through the northern Rockies.
At the same time, enough weak low level moisture convergence will
set up over central and northeast Missouri and west central
Illinois on Thursday afternoon to cause isolated showers. These
scattered showers spread across the area on Thursday night.

Lows tonight will not be a cold given the increasing clouds and
winds staying up most of the night. Will keep lows in the 40s.
Have highs tomorrow in the 60s areawide as 850mb temperatures will
climb close to +10C.


.LONG TERM...  (Friday through Next Wednesday)
Issued at 353 PM CDT Wed Apr 1 2020

The NAM/GFS is in reasonable agreement that the upper trough will
move east into the Upper Midwest and brings a slow moving cold
front across Missouri and Illinois Friday into Saturday. At the
same time, there will be enough moisture transport ahead of this
system to continue likely/categorical PoPs for showers with chance
of thunderstorms. Rain chances Sunday and Sunday night will only
be slight as both the GEFS and EPS are showing a weak ridge moving
over the area. Better chances will come back early next week when
a warm front will move back across the area bringing showers and

Temperatures are expected to gradually warm up through the period.
Highs on Saturday will be held down by cold air advection and
clouds and rain with highs only 50s and 60s. Highs by early next
week will warm into the 70s to near 80 behind the warm front based
on the ensemble forecast plumes and forecast 850mb temperatures
near +15C.



.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 620 PM CDT Wed Apr 1 2020

VFR conditions, SE surface winds, and dry weather are expected at
the TAF sites for much of the valid period. Gusty winds to 20kts
will be likely during Thursday afternoon during peak mixing,
otherwise sustained winds will mainly be around 10kts. Scattered
showers will wander into near KCOU and KUIN late Thursday
afternoon/early evening to justify a VCSH mention.

SPECIFICS FOR KSTL: for the extended 6-hour period, scattered
showers will wander into the vicinity of the terminal just before
the end of the valid period late Thursday evening for a VCSH.





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