Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 291219
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
719 AM CDT Mon Jun 29 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 148 AM CDT Mon Jun 29 2015

Weak surface low just northeast of STL will continue moving
eastward.  The thunderstorms have shifted east or south of our
forecast area, with only a few lingering showers between STL and
SLO.  Some fog has developed across west central IL and northeast MO
between UIN and HAE where the temperature has fallen into the 60s
and the wind has become light.  Will likely get at least isolated to
widely scattered showers and a few storms across our area this
afternoon as the atmosphere destabilizes with weak northwest flow
shortwaves moving southeastward through our area.  It appears that
the best coverage will be across northeast MO and west central and
southwest IL where there will be cooler mid level temperatures
associated with the upper level trough and hence better lapse
rates.  High temperatures today should also be a little cooler
across this area as well.

GKS

.LONG TERM:  (Tonight through Sunday)
Issued at 345 AM CDT Mon Jun 29 2015

At least isolated to widely scattered showers and a few storms
during the afternoon and evening will continue Tuesday.  High
temperatures will be slightly warmer on Tuesday as the upper level
trough shifts further eastward and warmer 850 mb temperatures advect
east northeastward into our area.  Rain chances will be increasing
late Tuesday night and Wednesday as a southwesterly low level jet
brings strong low-mid level warm air advection and 850 mb moisture
convergence to central MO by 12Z Wednesday.  More cloud cover and
more widespread precipitation will lead to cooler high temperatures
on Wednesday.  A good chance of convection will continue through at
least Wednesday night as a relatively weak surface low moves
eastward through southern MO.  Much of the precipitation may shift
southeast of our forecast area on Thursday as this surface low
shifts east southeast of the region with at least weak surface
ridging extending from the northern Plains and Great Lakes region
south southwest into our area.  This may only be a brief break in
the wet pattern as both the GFS and ECMWF models bring an upper
level trough east southeastward through our area late Thursday night
through Friday night.  This upper level trough with embedded
shortwaves should lead to at least scattered showers/storms during
the afternoon and evening hours.

GKS

&&

.AVIATION:  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 714 AM CDT Mon Jun 29 2015

Large area of with LIFR ceilings and visibilities that is already
affecting KUIN will drop southward and move into the St. Louis
metro area TAF sites between 12-14Z. Expect mixing to gradually
cause improvement to VFR at all of the TAF sites between 16-19Z.
There is a chance of thunderstorms this afternoon at KUIN and the
St. Louis metro area TAF sites, however the chance looks too low
to include in the TAFs at this point.

Specifics for KSTL: Expect LIFR ceilings and visibilities to move
into the area from the north around 13Z. These conditions will
gradually improve later this morning as mixing increases in the
atmosphere. Scattered thunderstorms will be found in the area
between 18-00Z, though have not included them in the TAF at this
point as the coverage will not be great enough.

Britt

&&

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

$$

WFO LSX





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