Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 181737

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1237 PM CDT Sun Jun 18 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 250 AM CDT Sun Jun 18 2017

Complex of thunderstorms that moved across much of the area has
pushed southeast of the CWA as the cold front continues to move to
the southeast. Lingering showers and a few thunderstorms will be
possible through midday over the southeast half of the CWA as there
will still be some ascent ahead of mid-level trough that will move
across Missouri and Illinois later in the day.  Clouds will clear
out slowly today and there will be some cold air advection which
will allow for cooler temperatures than yesterday. A blend of MOS
highs look good for today.

Skies will turn mostly clear behind the mid level trough axis
tonight.  With light westerly winds tonight and limited clouds,
temperatures should be able to fall to the agreeable MOS lows
near 60 degrees.


.LONG TERM...  (Monday through Saturday)
Issued at 250 AM CDT Sun Jun 18 2017

Looks like a period of quieter weather for the area through the
middle of next week.  High pressure at the surface and northwest
flow aloft through Tuesday should keep temperatures near normal with
lower humidity than we`ve had the past few days.  The high will
drift east of the area on Wednesday and southerly flow will bring
higher humidity and warmer temperatures back to the area.  GFS and
ECMWF both develop a low level jet Wednesday night as the next
upstream trof strengthens over the Great Plains and the associated
850mb moisture convergence forces some nocturnal convection over
western and northern portions of the CWFA late Wednesday night.

Medium range models diverge toward the end of the week with the GFS
developing a deeper longwave trof over the central CONUS than the
ECMWF toward the end of the week.  This makes the GFS faster in
shifting a cold front southeast through the Plains into the Midwest
than the ECMWF.  The result is that Friday and Friday night are
wetter on the GFS as the front moves through while the ECMWF is
warmer and wetter on Saturday.  Stuck closer to ensemble forecasts
which lean toward the GFS that far out with likely PoPs Friday night
and a mostly dry and cooler Saturday.



.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1222 PM CDT Sun Jun 18 2017

VFR and dry conditions are expected thru the period. Winds will
remain nwly to wly. Gusty winds today will diminish with sunset as
well as CU dissipating with few high clouds for the remainder of
the TAF period.





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