Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 291752
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1252 PM 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 favorably 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 aggressively 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 18z TAFs through 18z Monday Afternoon)
Issued at 1237 PM CDT Sun Mar 29 2015

VFR flight conditions with gusty south-southwest flow will prevail
this afternoon across the area. Isolated showers will continue
move from west to east, and short range guidance continues to show
a line of showers redeveloping along the I-70 corridor later this
afternoon. Further south...an area of MVFR stratus with ceilings
around 2500 FT will just scrape by our southern forecast
area, primarily south of a line from KFAM to KSAR to KSLO; although
those sites may see a brief period of MVFR if the stratus can get
far enough north. The cold front currently over northwest Missouri
will sweep southeast later this afternoon and finally bring the
shower activity to an end. Expect wind to shift to the northwest
and the sky to become clear behind the front.

Specifics for KSTL:

Expect VFR flight conditions and gusty south-southwest flow to
prevail at Lambert this afternoon. Short range guidance continues
to show a line of showers redeveloping along the I-70 corridor
later this afternoon, and this band of showers will likely bring
some light rain to the terminal. Stratus over northeast Missouri
should remain well to the south-southeast of the terminal this
afternoon. The cold front currently over northwest Missouri will
pass through the terminal during the early evening and finally
bring the shower activity to an end. Expect wind to shift to the
northwest and the sky to become clear behind the front.

Carney

&&

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

$$

WFO LSX






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