Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 280242

942 PM CDT Sat Sep 27 2014

Issued at 942 PM CDT Sat Sep 27 2014

Forecast on track, with only real change needed was to go more
optimistic on cloud cover, with effectively clear skies across
nearly the entire forecast area.



.SHORT TERM:  (Through Late Tonight)
Issued at 236 PM CDT Sat Sep 27 2014

The expansive high pressure system centered in the Great Lakes
will continue to dominate the lower troposphere maintain dry
conditions and light winds. Lows tonight will be comparable to
those of early this morning, perhaps even a degree or so cooler.


.LONG TERM:  (Sunday through Next Saturday)
Issued at 236 PM CDT Sat Sep 27 2014


The blocky upper air pattern that has been in place across the
eastern 2/3rds of the Nation since the middle of last week will
gradually break down through early next week with more progression
noted. In the short term, the upper low presently meandering
across northern Iowa will weaken and become absorbed into an upper
trof evolving from southeast Canada into the Ohio Valley Sunday
into Monday. This will allow the low level anticyclone/high to
maintain its dominance and control of the sensible weather through
Monday. Temperatures during this period should remain above normal
and be similar (within a few degrees) to those experience over the
last few days. The high begins to lose its westward influence on
Tuesday but conditions are expected to remain dry and tranquil and
temperatures above normal.


The deep longwave trof evolving over the western U.S. the next
few days will progress into the Mississippi Valley Wednesday into
Thursday. The extended models have come into much better agreement
with the speed of the system and movement of the associated cold
front across the area Thursday/Thursday night. The chance of pre-
frontal showers and thunderstorms will gradually ramp up west to
east as early as Wednesday with the highest probability of storms
with the cold frontal passage. We will have to keep an eye on this
system and the instability available as shear will be seasonably
strong to promote organized thunderstorms. This front will also
usher a much cooler air mass into the region for the weekend, much
more typical of fall.



.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 607 PM CDT Sat Sep 27 2014

VFR flight conditions and light easterly flow will prevail through
tonight into Sunday. Expect localized MVFR fog in river valleys
and other sheltered spots. Visibility may occasionally drop into
IFR range in these locations in the early morning before sunrise.

Specifics for KSTL:

VFR flight conditions and light easterly flow will continue to
prevail at Lambert tonight into Sunday.





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