Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 221752

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1252 PM 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.


.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.



.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1247 PM CDT Mon May 22 2017

Watching a band of showers moving toward KUIN early this
afternoon. Believe they will be affected by this area of showers
with a few thunderstorms also possible through late afternoon.
Elsewhere, believe terminals should stay dry through the afternoon
and early evening. Chances for showers will increase very slowly
from northwest to southeast overnight tonight, with scattered
showers and storms possible everywhere on Monday afternoon. Cold
front will move through during the day with winds switching to the
north/northwest along with MVFR ceilings.


Should be dry and VFR through the evening and early overnight.
Chance of showers will increase slowly overnight tonight and early
Tuesday morning. Thunderstorms will also be possible ahead of a
cold front on Tuesday afternoon. Behind the front, look for winds
to become predominantly northwesterly along with ceilings possibly
becoming MVFR.





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