Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 212011
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
311 PM CDT Mon Apr 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 311 PM CDT Mon Apr 21 2014

Cold front has moved into Missouri and will continue to track to the
southeast this evening. Showers and some thunderstorms have
developed ahead of cold front, but they will remain scattered in
nature before coming to an end late this evening. As for
temperatures, not a lot of caa behind this front so will have lows
in the mid 40s to mid 50s.

Byrd

.LONG TERM:  (Tuesday through Next Monday)
Issued at 311 PM CDT Mon Apr 21 2014

Skies to clear out by daybreak on Tuesday with north winds
persisting throughout the day. So a bit chillier but highs will be
in the mid 60s to low 70s.

Then surface ridge to move off to the east by Wednesday allowing
southerly winds to return ahead of next weather system. Highs on
Wednesday will be in the upper 60s to mid 70s.

Showers and thunderstorms to develop along frontal boundary late
Wednesday night and spread east. Best chances of precipitation will
be during the day on Thursday. Front to move through during the
afternoon and evening hours with decent instability, i.e.
surface based capes between 500 and 1000 j/kg and deep layer shear
in excess of 40kts.  However, unsure yet what the severe potential
will be. As for highs on Thursday, they will be in the upper 60s to
low 70s.

Beyond that, next chance for precipitation will be Saturday night
through Monday. But extended models have timing and placement
issues, so no major changes at this time.

Byrd
&&

.AVIATION:  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1056 AM CDT Mon Apr 21 2014

At least scattered showers and thunderstorms are expected this
afternoon into the early evening hours as an upper level
disturbance moves eastward through the region, while a cold front
moves southeastward through the taf sites late this afternoon and
this evening. Looking at the latest radar trends it appears that
most of the shower activity early this afternoon should occur in
the UIN area, but showers and storms should develop in the COU
area later this afternoon and move through the St Louis metro area
particularly during the early evening hours. Although prevailing
conditions have been VFR outside of the showers so far, some of
the MVFR cigs over western MO will likely advect into the region
later this afternoon, plus there will likely be some MVFR cigs
just behind the cold front. Mainly southwesterly winds will veer
around to a northwesterly direction after fropa. The clouds
should clear out fairly quickly this evening in UIN and COU and
overnight in the St Louis metro area as a relatively strong
surface ridge builds southeastward into the region behind the cold
front.

Specifics for KSTL: Looks like a break in the shower activity
early this afternoon, but model guidance indicates that showers
and storms will develop and move through the STL area late this
afternoon and early this evening. These showers and storms should
shift southeast of STL by 04z Tuesday after fropa with the wind
veering around to a northwesterly direction. Will have VFR
conditions early this afternoon until the showers and storms move
into the area with the lowest prevailing cloud ceilings likely
this evening, possibly briefly down to around 1000-2000 ft. The
clouds should clear out shortly after 06z Tuesday.

GKS
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX




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