Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 220750

Area Forecast Discussion
National Weather Service Saint Louis MO
250 AM CDT MON AUG 22 2016

.SHORT TERM...(Through Late Tonight)
Issued at 247 AM CDT Mon Aug 22 2016

Ridge axis extends across northern Illinois southwest through the
STL Metro area and into far northwest Arkansas.  The ridge will
continue moving east today which will bring the wind around to the
south-southeast by mid to late morning.  The southerly flow and high
August sun angle will allow a solid warm up; however the cool start
to the morning will likely only allow highs in the low and mid 80s
even with a 30 degree warm up.

850mb flow turns around to the southwest tonight and models are
showing a few waves of low level moisture convergence in the warm
advection aloft.  Think the atmosphere will take most of the night
to moisten up enough for precip to develop, but I can`t rule out
some sunrise surprise convection over central Missouri before 12Z.
Have therefore introduced some slight chance PoPs from 10-12Z.


.LONG TERM...  (Tuesday through Sunday)
Issued at 247 AM CDT Mon Aug 22 2016

Not much change in thinking from the previous forecast that
scattered showers and thunderstorms will spread across the area from
west to east on Tuesday.  Both the GFS and ECMWF are showing low
level moisture convergence increasing on the nose of a 35kt low
level jet as the mid level flow turns west southwesterly.  This
unsettled pattern will continued through Thursday as a series of
weak shortwave troughs moves across the Mid Mississippi Valley. Will
still go with the highest chance of rain on Wednesday and Thursday
as a cold front moves southeast across the area. Thunderstorm
chances will shift to the southern half of the CWA on Thursday night
and Friday as the cold front moves into southeast Missouri and
southern Illinois at the same time a weak upper ridge works over the
area. By this weekend, the GFS and ECMWF are showing another upper
trough moving through the central CONUS that will bring another
chance of showers and thunderstorms to the region.

Temperatures will go from being be normal on Tuesday to near normal
on Wednesday and Thursday ahead of the cold front. Temperatures will
fall back below normal at the end of the week behind the cold front
late in the week.



.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1128 PM CDT Sun Aug 21 2016

Light winds thru sunrise as sfc ridge builds ewd. Winds will
become sly remaining below 10 kts on Mon with few CU developing.





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