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Area forecast discussion 
National Weather Service St Louis MO
335 am CDT Sat Aug 23 2014

Short term: (through late this afternoon)
issued at 332 am CDT Sat Aug 23 2014

Warm frontal boundary remains across region early this morning
with isolated/scattered storms firing north of it. A few have
moved into far northern portions of forecast area early this
morning. So have added isolated mention in this area through 15z
today. Otherwise, Summer has returned with a vengeance with
dangerous heat and humidity. Because of the high dewpts in the
upper 60s to mid 70s, lowered high temps a degree or two for
today. This will not affect heat indices as the higher dewpts and
slightly lower highs still create indices in the 100 to 109 degree
range once again. High resolution models want to generate
thunderstorm activity mainly east of Mississippi River this
afternoon but feel it will just skim our far eastern portions, so
added slight chance pops in this area.


Long term: (tonight through friday)
issued at 332 am CDT Sat Aug 23 2014

Models are keeping boundary draped across forecast area through
at least this evening before it weakens and lifts north late tonight.
So with front north of area on Sunday, it could be our hottest day
with temps approaching 100 for southern half of forecast area.
Heat indicies will once again be between 100 and 109. Will remain
hot through at least Monday, so will keep advisories and warnings
going through that period.

Still not confident on exact timing with next weather system, which
could begin to bring some rain to region by Tuesday, but just a
slight chance. Could see hot enough temps and heat indices on
Tuesday to keep headlines through then, but not confident enough to
do that at this time. Otherwise, will see better chances of rain
Wednesday through Thursday with temperatures cooling off.


Aviation: (for the 06z tafs through 06z Saturday night)
issued at 1111 PM CDT Fri Aug 22 2014

Although there may be isolated thunderstorms across much of the
area late tonight and Saturday in the humid and unstable
environment, the best threat for more widespread convection should
be north of the taf sites as a weak warm front lifts northward.
For now will leave the tafs dry. Should be just mid-high level
clouds outside of the convection late tonight and Saturday,
including high level convective debris cloudiness. Light surface
winds late tonight, then mainly weak sly surface winds on

Specifics for kstl: most of the convection should remain north and
northeast of stl this forecast period. Just mid-high level
cloudiness mainly late tonight and Saturday morning. The light surface
wind will only increase to 6-8 kts Saturday afternoon, mainly from
a sly direction.


Lsx watches/warnings/advisories:
MO...heat advisory until 7 PM CDT Monday for Audrain MO-Boone MO-
Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-
Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike
MO-Ralls MO-Reynolds MO-Shelby MO-St. Charles MO-St.
Francois MO-Ste. Genevieve MO-Warren MO-Washington MO.

Excessive heat warning until 7 PM CDT Monday for St. Louis city
MO-St. Louis MO.

Illinois...heat advisory until 7 PM CDT Monday for Adams Illinois-Bond Illinois-Brown
Illinois-Calhoun Illinois-Clinton Illinois-Fayette Illinois-Greene Illinois-Jersey Illinois-
Macoupin Illinois-Marion Illinois-Monroe Illinois-Montgomery Illinois-Pike Illinois-
Randolph Illinois-Washington Illinois.

Excessive heat warning until 7 PM CDT Monday for Madison IL-St.
Clair Illinois.


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