Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 231710
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1210 PM CDT Sat May 23 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 331 AM CDT Sat May 23 2015

Will continue to keep today mainly dry for parts of central and
southeast Missouri where the NAM shows some low level moisture
convergence developing in theses areas, especially later this
morning and this afternoon. The NCEP NMM WRF shows a few showers
developing over the area this afternoon. However, do not expect
widespread showers and thunderstorm development as the NAM also
shows an upper level ridge will build over the Midwest with the
NAM/ECMWF showing either neutral or subsidence over the area.
Temperatures will be slightly warmer today with 850mb temperatures
around +10C.

Britt

.LONG TERM:  (Tonight through Friday)
Issued at 331 AM CDT Sat May 23 2015

(Saturday Night through Monday Night)

NAM and ECMWF have shown better continuity than the GFS which also
shows gridscale feedback issues, so will use a blend of these two
models for the forecast solution.  Overall trends are pretty much
the same as going forecast. Upper ridge begins to move east tonight
which allows additional low level moisture convergence to move
into the area. Still expect a series of weak shortwave troughs to
move through the area in the southwest flow aloft with pockets of
low level moisture convergence. Will keep likely and categorical
PoPs going through this period. Will also go with a relatively small
diurnal swing given the clouds and rain. A blend of MOS guidance
looks reasonable given 850mb temperatures around +15C.

(Tuesday through Friday)

Will keep scattered thunderstorms in the forecast as upper flow
stays southwesterly with surface front staying nearby in a unstable
airmass.  ECMWF shows surface front moving just north of the area
which should allow temperatures to climb above normal by Thursday
and Friday.

Britt

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1153 AM CDT Sat May 23 2015

Specifics for KUIN: If the scattered rain showers moving out of
southwestern MO do not dissipate, then they would reach KUIN
around 21-23z. Otherwise, VFR conditions will prevail through the
evening and into the overnight hours. Precipitation chances
increase after 09z, but confidence is too low to include an
overnight SH/TS mention in the TAF attm. Precipitation chances
appear to be much higher after 24/18z. Winds remain southeasterly
to southerly through the period.

Specifics for KCOU: Scattered rain showers were approaching KCOU
at TAF issuance. A brief period of light rain is possible this
afternoon if a shower happens to move directly over the airport.
Once these showers have moved to the northeast and away from KCOU,
VFR conditions are expected for most of the evening. Another round
of SH/TS should be approaching the terminal by 09z with rain then
lingering through the morning hours. Winds remain southeasterly to
southerly through the period.

Specifics for KSTL, KSUS, KCPS: If the scattered showers moving
out of southwestern MO at TAF issuance do not dissipate this
afternoon, then they would reach the St. Louis metro area around
21-23z. Otherwise, VFR conditions will prevail through at least
tomorrow morning. The chance of SH/TS increases after 24/18z when
a low pressure system will have moved just far enough east to
spread precipitation into east central MO. Winds remain
southeasterly to southerly through the period.

Kanofsky

&&

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

$$

WFO LSX





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