Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 262324

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
624 PM CDT TUE JUL 26 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 316 PM CDT Tue Jul 26 2016

The weak elongated low level convergence zone from southern IL
thru southeast MO has been the focus for showers and thunderstorms
today. The threat area will remain virtually unchanged tonight
although I would anticipate decreasing coverage and intensity this
evening as diurnally enhanced instability diminishes and convergence
becomes less organized. From late evening into overnight the coverage
may be nothing more than random spot showers or thunderstorms within
this zone.


.LONG TERM...  (Wednesday through Next Tuesday)
Issued at 316 PM CDT Tue Jul 26 2016

In some respects the evolution, coverage, and intensity of storms
on Wednesday and Wednesday night may largely mimic what we have
seen today and anticipate tonight. The zone of low level convergence
is forecast to take a slight northward jaunt on Wednesday, so
there will likely be a bit more northward displacement to the
activity, and greater chance of storms in the St. Louis area.
Scattered to numerous storms would be centered on the afternoon
and then diminishing coverage by evening. Thursday into Thursday
night would appear to be the period with greatest coverage of
storms and highest threat of precipitation throughout the region.
A well-defined northwest flow short-wave trof will approach and
then traverse the region, first prompting the southern boundary
to return northward as a warm front, and then also dragging a
cold front into the across the area with the passage of a upper
wave and surface low. The front will then become stationary across
southern portions of the CWA or just south Friday-Friday night,
then waver northward over the weekend, keeping areas in the
vicinity of the frontal zone with a chance of showers and storms.

Present indications are that the pattern will change during the
first part of next week with progression aloft and the four
corners ridge shifting east and building through the central U.S..
This should result in the wavering quasi-stationary front
retreating back north of the area and a return of hot and humid
weather beginning on Tuesday.



.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 616 PM CDT Tue Jul 26 2016

Outflow boundary continues to move nwd this evening. A couple of
TSRA will be possible along this outflow. Have kept mention of
precip out of KCOU for now as this activity shud dissipate
quickly. Otherwise, fog is still possible overnight tonight. Still
mainly VFR conditions on Wed, but will continue to monitor threat
for TSRA during the afternoon hours. However, currently believe
the threat will remain just south of KSUS/KSTL/KCPS and shud
remain well south of KCOU.





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