Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 242044
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
344 PM CDT SUN JUL 24 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 320 PM CDT Sun Jul 24 2016

Oppressive heat and humidity blanket the area at mid-afternoon and
once again we are seeing a few short-lived showers and thunderstorms
across parts of south central and southeast MO. Like previous
days, there will continue to be a threat of these through early
evening. The greatest area of attention however turns to northeast
MO into west central IL this evening along and ahead of the slowly
advancing cold front, and then overnight as the front sags southward
to the St. Louis vicinity by 12z Monday. There is some CIN across
northern MO at this time, however the CAP will eventually erode
and the development of scattered thunderstorms is anticipated as
some weak ascent and slight cooling aloft spread across the area
attendant with an upstream impulse now in eastern KS/NE. Several
waves of multicell clusters are expected along and ahead of the
slowly advancing cold front both this evening and overnight. Any
severe threat would probably be this evening owing to greater
instability and be in the forming of damaging winds.

Glass

.LONG TERM...  (Monday through Next Sunday)
Issued at 320 PM CDT Sun Jul 24 2016

The cold front will continue to move slowly southward on Monday as
weak surface high pressure settles into the Mid-Upper MS Valley,
with the front in the vicinity of the bootheel/extreme southern IL
by early evening. Scattered thunderstorms/thunderstorm clusters
are expected to be ongoing at sunrise and continue along/ahead of
the advancing cold front. Both the precipitation and clouds along
with the frontal passage are expected to put an end to the
dangerous heat/prolonged heat wave with today being the last
thrust of extreme heat marked by HI values of 105-115+. The
excessive heat warning will be allowed to expire on schedule at
800 pm this evening. I should note that if the clouds are not as
great on Monday as expected and we see a tad higher temps, then
some HI values in the 100-102 range might occur from St. Louis
southward, however this is highly conditional and still a good
deal below the prominent readings of the last week.

From Monday night through Tuesday night I believe that the threat
of showers and storms should generally be confined to the frontal
corridor including southern MO and southern IL. Some of the
deterministic model guidance wants to generate precipitation much
further north into the cool sector, however the lack of a
"overrunning" south-southwesterly LLJ to provide the lift or an
appreciable short wave makes this suspect. Weak high pressure to
the north of the front will dominate, and the weather will largely
feature lower RH and cooler/near average temperatures.

A somewhat unsettled pattern is forecast to dominate the period
from Wednesday into early next weekend. An upper high will be
anchored in the western U.S. with broad mean trof through the
upper MS Valley-Great Lakes-northeastern U.S.. The resultant
broadly cyclonic flow - west/northwest aloft - will feature a
somewhat steady stream of short waves or lower amplitude
disturbances. These features and a wavering frontal boundary will
result in a continuous chance of showers and thunderstorms.
Temperatures are expected to be near average during this period.

Glass

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1233 PM CDT Sun Jul 24 2016

Cold front continues to make very slow progress to the south into
northern Missouri as of 17z. So hard to time when storms will
develop so kept vcts mention for now, after 22z at KUIN, after 00z
at KCOU and not til Monday morning for metro area tafs. Otherwise,
vfr conditions with scattered cu and mid clouds moving in. South
winds to veer with time as front moves south. Winds to veer to the
north by 01z at KUIN, by 04z at KCOU and around 13z Monday for
metro area.

Specifics for KSTL:
Cold front continues to make very slow progress to the south into
northern Missouri as of 17z. So hard to time when storms will
develop so kept vcts mention for now and will not move into metro
area til after 13z Monday for metro area. Otherwise, vfr
conditions with scattered cu and mid clouds moving in. South winds
to veer with time as front moves south. Winds to veer to the north
by 13z Monday for metro area.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Excessive Heat Warning until 8 PM CDT this evening 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-Saint Charles MO-
     Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte
     Genevieve MO-Shelby MO-Warren MO-Washington MO.

IL...Excessive Heat Warning until 8 PM CDT this evening for Adams IL-
     Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-
     Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-
     Montgomery IL-Pike IL-Randolph IL-Saint Clair IL-Washington
     IL.

&&

$$

WFO LSX



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