Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 170451

1151 PM CDT Wed Apr 16 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 233 PM CDT Wed Apr 16 2014

A rather tranquil night is on tap for the area. The surface low
currently in extreme northwest Iowa will move northeastward tonight
and into Wisconsin by daybreak, with the attendant cold front
stretching from northeast MO into west central MO at 12Z. As a
result the surface pressure gradient will weaken this evening. This
along with an end to deep mixing around sunset will result in
quickly diminishing southerly surface winds. Surface winds do remain
southerly all night but due to extensive lower tropospheric ridging
well into the GOM, low level moisture return will be nil and limited
to an increase in mid-hi level moisture. The associated cloudiness
and southerly winds will keep temperatures warmer than last night.


.LONG TERM:  (Thursday through Next Wednesday)
Issued at 322 PM CDT Wed Apr 16 2014

A weak cold front will move southeastward through our forecast area
Thursday and Thursday night.  The models depict upper level
divergence over our area Thursday and Thursday evening ahead of an
approaching upper level trough.  Moisture and instability will be
limited with this front, but there should still be scattered showers
along and just behind this front Thursday afternoon and night.  The
threat for showers should end Friday morning with a clearing sky as
the upper level trough moves east of the region.  Only slight
cooling is expected behind the front, mainly across northeast MO and
west central IL Thursday afternoon and night.  Temperatures will
warm back up Friday and Friday night as the upper level heights rise
as the upper level trough moves east of our area and as upper level
ridging centered over the southern Plains moves into our area.  Much
warmer, above normal high temperatures are expected on Saturday as
southerly surface/low level flow returns.  The chance of showers
will return to our area Sunday and continue through Monday as a
shortwave approaches and a weak cold front moves southeastward
through our area Sunday night and Monday.  It appears that there
will be more favorable level low moisture and instability present
with this weak front than the front which will move through our area
Thursday and Thursday night and hence a greater threat for showers
and possibly also thunderstorms.  Ony short lived, slight cooling
expected behind this front, then pronounced warming for Wednesday
with an upper level ridge over the region and strengthening sly/swly
surface/low level flow.  The models are forecasting 850 mb
temperatures rising to around 12-16 degrees C by 00z Thursday.



.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1149 PM CDT Wed Apr 16 2014

Anticipate conditions will remain VFR despite a frontal passage
tomorrow morning. South wind will swing around to the northwest
with the front and then relax, becoming light and variable
Thursday evening. The lack of low level moisture keeps the
forecast dry at this time.

Specifics for KSTL:

VFR conditions with a south wind becoming southwest tomorrow
morning and then shifting to the northwest with the cold front
early tomorrow afternoon. Wind to become light and variable
tomorrow evening. VFR clouds possible behind the front, but
moisture looks limited, with a dry forecast continuing.





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