Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 272041

Area Forecast Discussion
National Weather Service Saint Louis MO
341 PM CDT WED JUL 27 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 337 PM CDT Wed Jul 27 2016

Scattered thunderstorms will continue into the evening, particularly
along and south of I-70 where the low level convergence will be the
strongest nearest the quasi-stationary front currently over southern
Illinois and southeast Missouri.  This front will lift northward
into the area tonight which will keep at least a slight chance of
showers and thunderstorms going through the night, particularly as a
weak vort moves into the area from the northwest.  Lows tonight will
likely fall be in the lower to mid 70s which is close to MOS lows.


.LONG TERM...  (Thursday through Next Wednesday)
Issued at 337 PM CDT Wed Jul 27 2016

(Thursday and Friday)

NAM and GFS are in good agreement that a mean upper trough will set
up over the Midwest late this week into the weekend. A series of
vort maxes will move through the area which will help generate
scattered thunderstorm development which will be most likely
during daytime heating. Spatial distribution of thunderstorms will
also be favored along the wavy frontal boundary which is currently
just south of the area, but which will likely lift north tonight
into early Thursday before it will move back southward as a cold
front tomorrow afternoon. The front will once again be stalled
over Missouri and Illinois by Friday.

Temperatures during this period will be at or just below normal with
the front nearby.  Forecast soundings are showing mixing up to the
850-800mb layer with values of 15-17C.

(Saturday through Wednesday)

The global models are in generally good agreement that the upper
trough across the center of the CONUS over the weekend will move
eastward and off the East Coast by the middle of next week.  This
will allow yet another large and very warm upper high to spread
northeastward from the Desert Southwest into the central CONUS by
the middle of next week. It still looks like the quasi-stationary
front will remain over the area through the weekend into early
next before the front lifts northeast of the area once the upper
high builds eastward. Temperatures will gradually warm through the
period, going from below normal temperatures to above normal
temperatures as the upper trough moves off and the highs builds



.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1131 AM CDT Wed Jul 27 2016

Weak northwest flow aloft with a stalled frontal boundary to the
south will create a typical mess of a summer forecast. Scattered
showers and thunderstorms could pop up almost anywhere. A weak
vort max along with some moisture convergence has caused a few
small storms to form over west central Illinois. UIN may just be a
bit north of this area but will consider a vcty. These features
should cause more scattered storms to form over east central mo
into southern Illinois this afternoon, but as usual timing and
location is like throwing darts. A vcty will cover and then amend
as they form. As the stalled front to the south slowly begins to
lift north, showers and storm may become more numerous for much of
the region.

SPECIFICS FOR KSTL: With a weak wave moving across northern mo
into IL would expect scattered showers and storms to form this
afternoon. A vcty will cover until they form and they amend
accordingly. Storms should wane overnight with more forming
Thursday as the frontal boundary to the south begins lifting





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