Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 240340

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1040 PM CDT Mon Apr 23 2018

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 338 PM CDT Mon Apr 23 2018

Coverage of showers has decreased over eastern Missouri and
Illinois this afternoon as low level moisture convergence and
upper level ascent has diminished. These showers will continue to
decrease tonight as the upper level low currently located over
the Bootheel slowly drifts east tonight and tomorrow. The clouds
will be slow to clear the area through tomorrow, especially over
eastern Missouri and southwest Illinois where moisture will
continue to rotate into the region. There will be some sun,
especially by afternoon over central and northeast Missouri as
well as west central Illinois. With less rain and more sun,
temperatures should be warmer tomorrow, ranging from the lower 60s
where the clouds persist to the the lower 70s where the sun
manages to break out.


.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 338 PM CDT Mon Apr 23 2018

Not much has changed from the previous forecast.  The GFS/ECMWF/
Canadian are in relatively good agreement that two upper level
storm systems will move across the area in northwesterly flow
this week before a large upper ridge builds over the central CONUS
this weekend. An upper level low will move from the central
Plains into the Lower Mississippi Valley on Wednesday bringing a
chance of showers and a few thunderstorms to central and southeast
Missouri. A second trough will then move through the central CONUS
Thursday night and Friday bringing another chance of showers. The
weekend currently looks dry with the upper level ridge building

Temperatures are expected to go from just below normal to above
normal by this weekend once the upper ridge builds over the area.
All of the extended MOS as well as the GEFS guidance is
suggesting highs in the 70s if not 80 this weekend and early next



.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1030 PM CDT Mon Apr 23 2018

Still expect MVFR cigs to move back west overnight an impact
KCOU/KUIN before moving east again on Tues. Believe dewpoint
spreads are wide enuf that fog will remain east of these terminals.
Winds are expected to be fairly light and remain nely to nly.

SPECIFICS FOR KSTL/KSUS/KCPS: Still expect cigs to drop to IFR
around 06z, tho KSTL and KPCS has already dropped to IFR. Can not
rule out a brief sprinkle, but much of the rain continues to
dissipate before reaching the terminals. Dewpoint depressions
remain low, however, mixing has been a bit stronger than prev
anticipated and may prevent any fog formation. Still, kept some
fog in TAF as IFR cigs will drive conditions. Otherwise, winds
will remain nely to nly thru the period. IFR cigs will lift mid to
late morning Tues and become VFR during the early afternoon.





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