Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 221152
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
652 AM CDT Mon May 22 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 307 AM CDT Mon May 22 2017

Surface ridge to continue moving off to the southeast today, so will
see winds become southerly once again. In the meantime, next system
approaching region from the northwest with increasing low level
moisture and instability. Showers and storms to develop and spread
east and northeast through northern MO and into west central IL by
this afternoon. A lot of dry air to overcome, so activity will be
slow to make much in the way of southeast progress, thus it will not
move into STL metro area, as well as areas to the south and east
of metro, til late this evening.

As for temperatures, highs today will depend on cloud cover and
precipitation. For now have highs in the low to mid 70s, while lows
tonight will be in the 50s.

Byrd

.LONG TERM...  (Tuesday through Sunday)
Issued at 307 AM CDT Mon May 22 2017

Overall, mdls are in good agreement thru the short term. Period will
begin with upper low moving swd from the Great Lakes region. The
area will remain under cyclonic flow thru Thurs before heights begin
to rise again.

This upper low/trof sinks swd Tues into Wed bringing a reinforcing
cdfnt thru the region and more rain. The upper low is progd to then
move 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. Thurs continues to be questionable and wud
expect the region to see more clouds given the cyclonic flow.
However, mdls are suggesting fewer clouds, tho far from a clear sky.
Have begun the warmup for Thurs but overall the forecast is a
compromise of guidance. Temps return to more seasonal avg on Fri as
the wrmfnt lifts nwd thru the region.

Tilly
&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 648 AM CDT Mon May 22 2017

Surface ridge to move off to the southeast today as next system
approaches region. Will have VFR conditions, though cigs will
lower to low end VFR this evening. KCOU and KUIN will see rain
chances move in by this afternoon, with MVFR cigs by 10z Tuesday.
Hard to pin down coverage and timing of precipitation, so just
kept vicinity showers or storms. As for winds, to pickup a bit
from the south before becoming light and variable once again
tonight.

SPECIFICS FOR KSTL:
Surface ridge to move off to the southeast today as next system
approaches region. Will have VFR conditions, though cigs will
lower to low end VFR this evening. KCOU and KUIN will see rain
chances move in by this afternoon, with MVFR cigs by 10z Tuesday.
As for winds, to pickup a bit from the south before becoming light
and variable once again tonight.

Byrd
&&

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

$$
WFO LSX



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