Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 232304

604 PM CDT Sat May 23 2015

Issued at 145 PM CDT Sat May 23 2015

The middle to upper levels of the atmosphere feature a deep trof
of low pressure centered over the Four-Corners Region with
resulting southwest flow downstream across the southern Plains.
Embedded shortwave in this flow continues to produce heavy showers
and thunderstorms across KS and OK. Further east, weak warm
advection and moisture convergence along and north of the 850mb
warm front was responsible for isolated to widely scattered
showers across mainly southwest Missouri.



.SHORT TERM: (Through Tuesday)
Issued at 145 PM CDT Sat May 23 2015

Main thrust of precipitation should remain just to the west of the
CWA through tomorrow morning with the highest PoPs and QPF
concentrated across our central and northeast MO counties. That
doesn`t mean it will be completlely dry though, as isolated to
scattered showers cannot be ruled out as far east as the Mississippi
River as the 850mb warm front lifts north.

Appears that the first round of precipitation should pull northeast
of central and northeast MO during the morning hours with a threat
of renewed thunderstorm development during the afternoon and evening
areawide. Have maintained general trend of chance/sct PoP increasing
to likely during the afternoon, especially west of I-55. Believe
there will be enough dry time for temperatures to warm into the
upper 70s/lower 80s.

Sunday Night...
Not sure exactly how Sunday night will play out, as it will depend
on convective trends during the afternoon and evening. Model
guidance depicts a decent shortwave moving northeast across the area
which would make one think there should be some pretty good coverage
of precipitation. I have kept a blanket of categorical PoPs based on
pattern recognition more than anything.

Memorial Day...
At this point it looks like the vast majority of the area will be
dry on Memorial Day as the shortwave lifts northeast of the area and
we are located in area of subsidence for the daylight hours. I
suppose I can`t rule out an isolated thunderstorm developing since
we are still in southwest flow aloft and will be quite unstable, but
chances are pretty low since there is no obvious trigger.
Temperatures should be quite warm for the unofficial start of summer
with highs in the lower to middle 80s.

Monday night and Tuesday...
Next shortwave in the southwest flow parade will bring a renewed
threat of showers and thunderstorms to the CWA Monday night into
Tuesday. Temperatures may struggle some on Tuesday with cloud cover
and expected rain coverage, so knocked anticipated highs down a few
degrees across the southeastern half of the CWA.

.LONG TERM: (Tuesday Night through Next Saturday)
Issued at 145 PM CDT Sat May 23 2015

The pattern looks to remain quite active with southwest flow
expected through the period. Each shortwave will bring with it a
chance of thunderstorms and temperatures should remain warm, with
afternoon highs in the lower to middle 80s.



.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 533 PM CDT Sat May 23 2015

Mid-high level clouds will continue across the area tonight with
showers likely moving through COU late tonight and into UIN
towards morning. Could not rule out sprinkles in the St Louis
metro area tonight, but the better chance of showers/storms should
hold off until Sunday afternoon and evening as a sly low level jet
moves through the area. Prevailing cloud ceilings will also lower
on Sunday, likely into the MVFR catagory in UIN and COU and down to
MVFR or at least low end VFR in the St Louis metro area by
afternoon. Sely surface wind will continue tonight, becoming
relatively strong and gusty from a s-sely direction on Sunday.

Specifics for KSTL: Prevailing VFR mid level cloudiness tonight,
then the ceiling will lower into the MVFR or low end VFR catagory
by Sunday afternoon. May be some sprinkles tonight from mid level
clouds, but the better threat of showers/storms should occur
Sunday afternoon and evening. Sely surface wind tonight will
strengthen and become gusty by late Sunday morning or afternoon
from a s-sely direction.





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