Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 280455
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1155 PM CDT Sat Sep 27 2014

.UPDATE:
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.

TES

&&

.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.

Glass

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

Sunday-Tuesday

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.

Wednesday-Saturday

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.

Glass

&&

.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1145 PM CDT Sat Sep 27 2014

Expect VFR flight conditions and light easterly flow to continue
to prevail across the area tonight. Localized fog reducing the
visibility to MVFR and at times IFR will be possible again in
river valleys. Some scattered clouds have developed over central
Missouri and I expect these clouds to persist for much of the
night and perhaps expand further east. Any fog should dissipate
quickly after sunrise and VFR flight conditions will prevail for
the rest of the day on Sunday.

Specifics for KSTL:

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

Carney

&&

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

$$

WFO LSX





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