Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 290840
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
340 AM CDT Sun Mar 29 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 324 AM CDT Sun Mar 29 2015

Main forecast issues today are the chance of rain and the amount
of temperature moderation. Mid level based showers have been slowly
increasing in coverage from western Iowa into eastern Nebraska in
association with strong warm advection and large scale ascent in
advance of a digging trof. Virtually all the guidance has this
trend continuing this morning as showers spread into northeast MO
and west central IL and then gradually backbuild some into central
MO this afternoon. Temperatures today should be a good deal warmer
than yesterday thanks to gusty southerly winds and warm advection
ahead of the encroaching cold front, but will still be a bit below
average for late March.

Glass

.LONG TERM:  (Tonight through Saturday)
Issued at 324 AM CDT Sun Mar 29 2015

A few lingering showers may affect parts of southeast MO and
southwest IL early this evening. Otherwise the cold front will be
entering the St. Louis area early tonight and settle into the
lower MS and TN Valley region by Monday morning as weak high
pressure builds into the area. The center of the high will settle
south and southeastward on Monday with surface winds backing to
southwesterly and the development of decent WAA from late morning
into the afternoon. Temperatures should respond favorbably warming
to seasonable levels. Surface winds remain southwesterly Monday
night into early Tuesday and the GFS at least thinks this may push
some stratus into the area. The flow however quickly veers above
the surface to westerly and northwesterly and this is not a
typical scenario for seeing stratus and low level moisture return
as agressively as the GFS thinks. Another weak cold front moves
into the area on Tuesday and moisture ahead of it remains poor in
quality and shallow. This front settles southward into the lower
MS and TV Valley are Tuesday night as high pressure builds
southeastward through the Great Lakes into the OH Valley. Low
level moisture return and quality should improve Wednesday into
Wednesday night however it will be a slow process as the moisture
initially remains quite shallow.

The threat of showers and thunderstorms in the Wednesday night
through Friday period still looks on track although there remains
uncertainty with the progress and position of the associated cold
front and potential development of a migrating frontal low
pressure wave Thursday night into Friday. These variances in the
deterministic models are at least partially due to the differences
in the models with disturbances in the west-southwest flow aloft.

Glass

&&

.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1142 PM CDT Sat Mar 28 2015

Gradient to continue to tighten over region ahead of cold front
that will move through Sunday afternoon. Southeast to south winds
to pickup by mid morning with gusts to near 25kts at times. As for
precipitation, a lot of dry air to overcome but best chances will
be along and east of Mississippi River as system moves through.
Front to move through KUIN by 19z Sunday, KCOU by 21z Sunday and
metro area by 23z Sunday with winds veering to the west and
diminishing behind the cold front.

Specifics for KSTL:
Gradient to continue to tighten over region ahead of cold front
that will move through Sunday afternoon. Southeast to south winds
to pickup by 15z Sunday with gusts to near 25kts at times. As for
precipitation, a lot of dry air to overcome but best chances after
19z Sunday, for now just have vfr cigs/vsbys with showers. Front
to move through metro area by 23z Sunday with winds veering to the
west and diminishing behind the cold front.

Byrd

&&

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

$$

WFO LSX





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