Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 251740
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1240 PM CDT Mon May 25 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 338 AM CDT Mon May 25 2015

Area of showers currently over west central Missouri will move
northeast and will affect some of the northeast Missouri counties
before 9 am ahead of the mid level shortwave that will move out of
the area by mid-morning. Otherwise, expect a drier day today as
area will lie under subsidence in the wake of the shortwave
trough. Only exception will be over parts of central and southeast
Missouri into southern Illinois where the atmosphere will become
unstable which could still lead to a few showers and thunderstorms
developing during the afternoon hours. High temperatures this
afternoon will be close to what they were on Sunday, which were in
the lower-mid 80s.

Britt

.LONG TERM:  (Tonight through Sunday)
Issued at 338 AM CDT Mon May 25 2015

(Tonight through Wednesday)

Will continue to follow the NAM/ECMWF which has had the best
continuity as of late.  Have kept with current trends on PoPs
tonight into Tuesday.  A shortwave ridge will move off to the east
of the area tonight which will allow for a rapid increase in ascent
after 06Z caused by the approach the next mid-level trough and
increasing low-level moisture convergence.  Will keep likely PoPs
over much of the southern half of the CWA of the area after midnight
tonight, and continue them into Tuesday morning as the mid-
level trough moves through before the showers and thunderstorms
become scattered during the afternoon.  The chance of thunderstorms
will continue Tuesday night into Wednesday as another weak shortwave
moves across the area.

(Thursday through next Sunday)

Rain chances will continue into the extended part of the forecast as
upper trough over western CONUS moves into the Great Plains and
eventually through Middle Mississippi Valley by next Sunday.  ECMWF
shows a series of shortwave troughs with attendant low level
moisture convergence moving through the area ahead of this main
trough.  This is worth keeping a chance of showers and thunderstorms
in each day with the best chance on Saturday when ECMWF currently
shows a cold front moving through.  Temperatures will stay close to
normal with 850mb temperatures in the 10-15C range.

Britt

&&

.AVIATION:  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1225 PM CDT Mon May 25 2015

VFR conditions are expected to prevail at all TAF sites this
afternoon and into the evening hours unless a rogue thunderstorm
develops and happens to move directly over one of the terminals.
The chance of afternoon TSRA appears to be higher at
KCOU/KSTL/KSUS/KCPS than at KUIN due to those sites` proximity to
an outflow boundary which moved into the region earlier this
morning. A period of rain showers with embedded thunderstorms is
expected to lift northeastward and affect all terminals late
tonight and tomorrow morning. MVFR cigs and precipitation are
expected to reach KCOU around 06-09z, KSTL/KSUS/KCPS around
08-11z, and KUIN around 10-13z. Initially southwesterly winds will
gradually back and become more southerly or southeasterly today
and tonight, then become southwesterly again towards the end of
the valid TAF period.

Kanofsky

&&

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

$$

WFO LSX





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