Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 231544

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
1044 AM CDT Fri Jun 23 2017

Issued at 1043 AM CDT Fri Jun 23 2017

Cold front has moved southeast through about halfway across the
CWA late this morning. The heaviest showers and isolated
thunderstorms associated with the remnants of Cindy are just south
of the CWA over far southeast Missouri into southern Illinois.
Will keep with a chance of showers and a few thunderstorms ahead
of the front the rest of the morning into the early afternoon.
The chance will diminish over the southeast Missouri and southwest
Illinois counties by late afternoon as front pushes south of the
area. The clouds will also show some slow clearing as upper clouds
pushes off to the east and drier air moves in behind the cold
front. Going highs still look good for today.



.SHORT TERM...  (Through Late Tonight)
Issued at 330 AM CDT Fri Jun 23 2017

Cold front extending from east central IA southwestward to
northwestern MO to sink slowly to the southeast today. In the
meantime, Tropical Depression Cindy, which is over central Arkansas,
will lift northeastward into far southern portions of MO bootheel
late this morning, then track eastward along TN/KY border. So
dealing with two areas of activity, showers and storms along cold
front that will continue to track southeast into northeast MO/west
central IL by 4-5 am timeframe and isolated/scattered storms over
remainder of forecast area due to T.D. Cindy. Coverage of activity
from both systems hard to pin down, but best chances will be over
east central and southeast MO, as well as southern IL through
midday, then taper off quickly during the afternoon hours as cold
front exits region. Because of clouds and precipitation, highs today
will be a bit below normal, in the low to mid 80s.

Dry and less humid air to make it`s way into region behind cold
front as skies clear out. So lows tonight will be in the mid 50s to
low 60s.


.LONG TERM...  (Saturday through Thursday)
Issued at 330 AM CDT Fri Jun 23 2017

Main focus thru the forecast period will be temps.

The cdfnt, currently approaching the CWA from the north, will be
south of the area by 12z Sat. With a deep upper trof settling across
the eastern two-thirds of the U.S. with NW flow across the region,
expect mostly dry conditions with well below seasonal average temps.
A reinforcing cdfnt will bring another shot of cooler temps on Sat.
However, this fnt will linger across srn portions of the CWA. A s/w
dropping into the region late Sun night into Mon will generate SHRA
along this fnt.

As the upper trof digs into the region, another reinforcing cdfnt
will drop thru the area. As the sfc ridge builds into the region,
expect Mon to be the coolest day of the forecast period. Temps shud
begin to rebound by Tues as sfc winds become sly and the thermal
ridge begins to build into the area. However, still expecting below
seasonal average temps thru at least mid week.

As sly flow returns, the chance for TSRA increases, mainly late in
the week. However, timing remains uncertain and have kept PoPs
fairly low attm.



.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1142 PM CDT Thu Jun 22 2017

An are of IFR ceilings developed over Illinois earlier in the
evening and is trying to spread very slowly westward. This area of
IFR ceilings may get into the STL Metro area later tonight, but
current model guidance is not very excited about this possibility.
Another area of MVFR ceilings developed over the eastern Ozarks
and is expected to spread slowly north through the remainder of
the night. A cold front over central Iowa will drop southeast
across the area from around 11Z through 17Z. Expect showers and
thunderstorms along and ahead of the front through the morning
hours. Also expect MVFR ceilings to move through with the
front...lifting and scattering out during the late morning and
afternoon from northwest to southeast.


IFR ceilings over central Illinois will try to build westward
toward the terminal...but model guidance is not showing that the
low ceilings will make it to Lambert. Otherwise, expect VFR
conditions to prevail until the cold front moves into the vicinity
of the terminal. Widely scattered showers and thunderstorms will
likely be in the vicinity of the terminal as the front moves
through. Expect an MVFR ceiling to move in with the front and
stick around through most of the morning before lifting and
scattering as drier air moves in behind the front.





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