Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 010411

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1111 PM CDT WED AUG 31 2016

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 315 PM CDT Wed Aug 31 2016

Band of showers and thunderstorms will continue to move southeast
late this afternoon and will be south of the CWA by early this
evening as low level winds begin to advect cooler and drier air into
the area.  Mid and high level clouds will begin to clear out of the
area by late this evening and overnight and north winds will be
light allowing for decent radiational cooling.  Even though the
northerly flow will be advecting in some drier air, recent rains as
of late have added to wet soils as well as warm river temperatures
should allow for some patchy fog late tonight and early tomorrow
morning. Any fog on Thursday morning will dissipate as skies will be
mainly sunny in the the morning.  Some diurnal cumulus is expect to
develop over the northeast half of the CWA by afternoon as a weak
mid level trough passes through the area.

Lows tonight will fall at or below MOS guidance in most areas as
drier air moves into the area.  Expect highs tomorrow to be closer
to warmer NAM MOS guidance which has values closer to 80 degrees in
most areas.


.LONG TERM...  (Thursday Night through Next Wednesday)
Issued at 315 PM CDT Wed Aug 31 2016

High pressure remains in control of the weather through the weekend.
The ridge will stay locked in over the region at least through
Sunday now due to a highly amplified blocking pattern with a deep
trof over the western CONUS and another amplified trof with
tropical influence over the eastern CONUS. Friday and Saturday
temperatures should be well below normal with highs the mid 70s to
near 80 and lows in the mid 50s to low 60s Sunday will probably be
warmer than Friday or Saturday due to airmass modification and
progressively more southerly flow on the western side of the
ridge...although temperatures will only climb to near normal in
the low 80s. Humidity will begin returning too, though current
indications are that dew points will only rebound into the low to
mid 60s.

Should see more summer-like temperatures and humidity for Monday
through Wednesday as deep southwest flow returns to the
Mississippi Valley. Could see some warm advection showers and
storms as early as 06-12Z Monday morning...primarily over northern
Missouri with some potential lingering into the daytime hours of
Monday. The rest of the forecast for Tuesday and Wednesday looks
warm and humid with only slight chances for any precipitation. A
strong upper level ridge will develop over the deep south and the
Mid Mississippi Valley will be on the northern periphery. There
also won`t be any synoptic boundaries in the area to focus
convection. With these two factors in play, any convection will
have to rely on orographic effects or mesoscale boundaries to
develop. Temperatures look to jump back above normal in the mid
and upper 80s.



.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1107 PM CDT Wed Aug 31 2016

Little change since prev TAF. Still VFR outside of expected steam
fog along rivers at SUS and CPS. Winds will be light overnight
increasing to nely around 10kts. Winds will diminish Thurs evening
around sunset. Expect SCT to possibly BKN CU to develop Thurs late
morning thru the afternoon, dissipating with sunset.





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