Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 042344

644 PM CDT SUN OCT 4 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 335 PM CDT Sun Oct 4 2015

Clearing has been expanding over the eastern part of the CWA this
afternoon as drier air has moved into the area.  Expect the clearing
line to make it into southeast and east central Missouri this
evening, though it should slow farther west because of the falling
of nightfall.  This is confirmed by model RH progs which show high
values in the surface-850mb layer from central Missouri into west
central Illinois through the night.  Lows tonight will vary
depending on cloud cover, and used a compromise of MOS guidance for


.LONG TERM:  (Monday through Next Sunday)
Issued at 335 PM CDT Sun Oct 4 2015

(Monday through Wednesday)

No big chances here as the big upper low over southeastern CONUS
moves east and out into the Atlantic as a ridge builds over the Mid
Mississippi Valley keeping the weather dry.  A surface high will
move over the Midwest at the same time keep the winds generally
light.   Temperatures will warm back above normal as 850mb
temperatures will be in the 10-15C range under mainly partly cloudy

(Thursday through Sunday)

GFS and ECMWF are in reasonable agreement that an upper trough will
drop southeastward out of the northern Plains across our area with
its attendant cold front on Thursday night or early Friday.  This
will be enough to keep a chance of thunderstorms going late this
week.  Then there is some uncertainty next weekend as the GFS brings
another trough across the area while the ECMWF just keeps fast
northwesterly upper flow.  Will go dry for now given this
uncertainty.  Temperatures will initially start out above normal
ahead of the front, but then fall back into the 60s and 70s behind
it as cooler air moves in.



.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 629 PM CDT Sun Oct 4 2015

MVFR cigs are expected to persist overnight at UIN/COU and lower.
UIN may have IFR cigs around sunrise Mon morning. Expect cigs to
be slow to lift eventually reaching VFR during the afternoon hrs.

Specifics for KSTL/KSUS/KCPS: A difficult forecast for the next 24
to 30 hrs. Edge of clouds has made it W of STL/CPS despite nly
low level winds and sunset. Can not rule out edge pushing a little
further W, but expect MVFR cigs to return to terminals this eve.
Regardless, currently anticipate IFR cigs developing late tonight
into Mon morning with cigs slowly lifting thru the day Mon. IFR
cigs may last longer than currently fcst, but will monitor trends
and update as needed.





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