Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 220446

1146 PM CDT Tue Oct 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 327 PM CDT Tue Oct 21 2014

Surface ridge extending from Wisconsin south-southwest through the
Mississippi Valley into the southeast Plains will drift to the
southeast tonight.  The upper level ridge will continue to build
overhead keeping the sky clear.  Expect light and variable surface
wind this evening to turn to the east southeast overnight as the
surface ridge drifts by.  With good radiational cooling conditions
for at least part of the night, expect temperatures to dip down to
near or slightly below this morning`s lows.  Used a combination of
consensus MOS and MAV for forecast lows tomorrow morning.


.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 327 PM CDT Tue Oct 21 2014

(Wednesday through Friday)

Dry weather is expected through Wednesday evening as a upper ridge
currently over the Plains will move across the area.  Then will
continue a slight chance for showers late on Wednesday night over
northeast and central Missouri as well as west central Illinois as
the GFS/NAM/ECMWF are all in good agreement that a upper trough will
approach the area.  This trough will move quickly across the area on
Thursday, though moisture will be limited with this system, so have
kept rain chances associated with this system in area mainly north
of I-70 where best ascent will be. Then subsidence will begin to
build into the area behind the trough, so expect dry weather to
return to the area for Thursday night and Friday.

Went toward the warmer GFS MOS for highs the next few days which
matches well with mixing down 900mb temperatures.

(Saturday through next Tuesday)

Weekend still looks dry and warm for late October as both the GFS
and ECMWF showing a large upper ridge building over the area.  850mb
temperatures will climb to near 15C as surface winds become
southerly by Sunday. Both the GFS and ECMWF MOS guidance support
high temperatures well into the 70s Saturday into Monday. By early
next week, the latest runs of the GFS/ECMWF are in good agreement
that a large trough will be moving through the Plains into the
Midwest with the attendant cold front reaching Missouri and
Illinois by Monday night. Will carry just low chances for showers
as there have been run-to-run model continuity issues which will
ultimately determine the timing of the rain early next week.



.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1137 PM CDT Tue Oct 21 2014

Surface high pressure extending from the southern Great Lakes
region through the Mid-Mississippi and Lower Ohio Valley regions
will slowly move southeastward through Wednesday evening. Surface
winds will generally be easterly tonight then become east-
southeast on Wednesday. Skies will remainn clear expect for some
local river fog possible for KSUS and KCPS where visibilities may
drop to 2 to 5 SM.

Specifics for KSTL: Northeast surface winds will become easterly
by daybreak 3 to 5 kts. Winds will slight shift to the southeast
by late morning or mid-day. Wind speeds will be under 5 kts
tonight and then 7 to 9 kts late Wednesday morning through early afternoon.
Skies will remain clear.





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