Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 232039

Area Forecast Discussion
National Weather Service Saint Louis MO
339 PM CDT Fri Jun 23 2017

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 338 PM CDT Fri Jun 23 2017

Cold front is about ready to push south of the area.  Still expect
the chance of showers and thunderstorms to move south of the area by
mid-late afternoon as drier and more stable air moves into the
region.  Subsidence will move into Missouri and Illinois this
evening in the wake of the remnants of Cindy.  Skies will turn
mostly clear tonight and on Saturday as the atmosphere becomes
increasing dry through a deep layer in zonal flow aloft.  A surface
high currently over southern Canada will move southeastward into the
central Plains by Saturday afternoon.  Current gusty winds will
decrease after sunset tonight.

Lows tonight and highs tomorrow will be close to agreeable MOS
guidance.  This also falls close to the SREF mean temps.


.LONG TERM...  (Saturday Night through Next Friday)
Issued at 338 PM CDT Fri Jun 23 2017

(Saturday Night - Tuesday Night)

Main story for this weekend into early next week will be the much
cooler than normal temperatures. Highs in the 70s to near 80
degrees during the day with lows in the 50s to near 60 degrees
appear likely. Exactly how cool it gets each night does appear
tricky however with clouds a concern on Sunday night, mainly
across southern and western sections of the forecast area. Timing
of surface high would suggest coolest conditions should be on
Sunday night/Monday morning, but some areas may be cooler Monday
night/Tuesday morning due to a clearer sky.

Deep longwave trough will amplify across the eastern 2/3 of the
CONUS this weekend into early next week. Northwest flow aloft will
prevail across the mid-Mississippi Valley with multiple reinforcing
shots of cooler air coming through the region. This period of time
still looks basically dry. Best chance for any precipitation will be
late Sunday night where modest warm advection occurs. Slight chances
for a shower/rumble of thunder as well Monday afternoon beneath
cyclonic flow aloft with weak instability and shortwave moving
through. Most will be completely dry however through Tuesday

(Wednesday - Next Friday)

Surface high will continue to slide eastward toward the mid Atlantic
on Wednesday. Should see warmer temperatures, along with increasing
chances for showers and thunderstorms late next week as flow aloft
becomes more zonal.



.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1222 PM CDT Fri Jun 23 2017

Band of MVFR clouds will move through St. Louis area terminals
through 20Z as a cold front move across the area. Otherwise dry
and VFR conditions are expected through the period. North to
northwest winds gusting up to around 20kts this afternoon
will diminish this evening.

SPECIFICS FOR KSTL: Band of MVFR clouds will move through Lambert
through 19Z before becoming dry and VFR the rest of the forecast
period. North to northwest winds gusting up to around 20kts this
afternoon will diminish this evening.





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