Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 211159
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
659 AM CDT Sun May 21 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 305 AM CDT Sun May 21 2017

Surface ridge continues to build into the region. So will see dry
and cooler conditions for today with some wrap around strato cu
possible for portions of northeast MO and west central Illinois this
afternoon. Otherwise, highs will be in the mid 60s to low 70s.

Surface ridge will remain over region tonight with clear skies and
light winds, so will see lows in the upper 40s to low 50s, about 5
to 10 degrees below normal.

Byrd

.LONG TERM...  (Monday through Saturday)
Issued at 305 AM CDT Sun May 21 2017

Overall, mdls are in good agreement thru the short term. Period will
begin with a nearly stacked upper low just NW of Lake Superior. This
low will keep the region under cyclonic flow thru Thurs before
heights begin to rise again.

A leading s/w is still progd to bring a chance of precip to nrn
portions of the CWA late Mon morning, before another trof rotates
around the low bringing a reinforcing cdfnt thru the region and more
rain. The upper low is progd to sink swd by mid week, then moving
ewd out of the area with the sfc ridge building into the area on
Thurs. This will allow for a dry period in the forecast, albeit
brief. The chance of TSRA returns as the wrmfnt lifts nwd on Fri and
continues into next weekend.

Given the persistent cyclonic flow, have trended temp twd the cooler
guidance thru mid week. The exception is Mon and have trended warmer
with more insolation expected, except for nrn portions of the CWA
where precip is possible sooner. Temps return to more seasonal avg
on Fri as the wrmfnt lifts nwd thru the region.

Tilly
&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 655 AM CDT Sun May 21 2017

Surface ridge has built into region with VFR conditions. However,
some wrap around strato cu on back side of system to move into
northeast MO/west central IL today, so KUIN could see broken MVFR
cigs. For now just have scattered cu there. Otherwise, rest of
tafs to have VFR conditions with west winds picking up by mid
morning. Winds will diminish and become light and variable late
tonight.

SPECIFICS FOR KSTL:
Surface ridge has built into region with VFR conditions. West
winds today will diminish and become light and variable by 04z
Monday.

Byrd
&&

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

$$
WFO LSX



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