Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 291809
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
109 PM CDT FRI APR 29 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 315 AM CDT Fri Apr 29 2016

Mid and high clouds from next system already streaming across
forecast area early this morning. But with dry east flow at surface,
it will take some time for the moisture to return. Instability will
be marginal as well. So mainly showers and a few thunderstorms will
develop over southern/western Missouri and increase in coverage to
the northeast. Otherwise, temperatures will be near normal in the
low 60s to around 70 for highs.

Byrd

.LONG TERM...  (Tonight through Thursday)
Issued at 315 AM CDT Fri Apr 29 2016

Models still have some placement issues with the area of low
pressure with the NAM further north than the GFS, and the ECMWF
somewhere in between. For now feel that warm front to develop and
lift north across forecast area tonight, stalling out along the
I70 corridor. Decent low level jet helping to bring in plenty of
moisture and will see elevated convection develop and track east
northeast across forecast area.

On Saturday, if system is further north we could see more of a
severe weather threat. With surface dewpts in the low to mid 60s,
will see surface based CAPES in excess of 2000 J/kg, but shear will
be weak. So SPC has placed areas along and south of I70 in a slight
risk for Saturday with the main threat being large hail.

All models are indicating closed upper level low to open up and lift
out late Saturday night and Sunday with rain coming to an end by
Sunday evening.

For the rest of the forecast period, it looks to be dry as a surface
ridge builds in. Will see some weak upper level shortwaves slide
across southern portions of the forecast area through this period,
but little in the way of precipitation is expected. Temperatures
will be a bit below normal on Monday, but expect highs in the low to
mid 70s by Wednesday and Thursday.

Byrd

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1245 PM CDT Fri Apr 29 2016

Specifics for KCOU: Mid/high clouds will persist ahead of an
approaching disturbance. SHRA/TSRA develop after 03z and persist
through the overnight hours, accompanied by MVFR cigs. Conditions
may fall to IFR at times.

Specifics for KUIN: KUIN is far enough north that MVFR cigs are
expected to persist for at least the next few hours and possibly
longer. Thereafter, mid/high clouds will continue to increase
ahead of an approaching disturbance. SHRA/TSRA develop after 06z
and persist into the morning hours, accompanied by MVFR cigs.
Conditions may fall to IFR at times.

Specifics for KSTL, KSUS, KCPS: A brief period of MVFR cigs is
ongoing at TAF issuance at KSTL but should improve quickly based
on recent obs at KSUS and KCPS. Mid/high clouds will persist ahead
of an approaching disturbance. SHRA/TSRA develop after 06z and
persist into the morning hours, accompanied by MVFR cigs.
Conditions may fall to IFR at times. Beyond the end of the 24hr
TAF pd, a second round of scattered thunderstorms is possible at
St. Louis metro area terminals after 30/21z.

Kanofsky

&&

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

$$

WFO LSX



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