Area Forecast Discussion
Issued by NWS St. Louis, MO

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057
FXUS63 KLSX 290840
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
340 AM CDT FRI JUL 29 2016

.SHORT TERM... (Today and Tonight)
Issued at 323 AM CDT Fri Jul 29 2016

The primary cold front is rather ill-defined early this morning
but best guess would place it across southwest IL and across
southern MO into northern OK at 08z. A shortwave trof will move
through the mid-upper MS Valley today and into the OH Valley
tonight. This will bring another secondary wind shift/front into
northern MO and central IL later this afternoon and across the
remainder of the area tonight. The combination of the boundaries
and the upper wave will result in a chance of showers and
thunderstorms, primarily across northern and southern sections of
the CWA this afternoon and this evening. Otherwise slightly cooler
and slight drier air will gradually filter into the region,
especially tonight in the wake of the second boundary as weak high
pressure settles southward from the upper MS Valley and Great
Lakes region.

Glass

.LONG TERM... (Saturday through Thursday)
Issued at 323 AM CDT Fri Jul 29 2016

The stalled front will be located in the vicinity of the MO/AR
border on Saturday and yet another weak wind shift will drop into
northern MO and central IL. Once again it would appear any threat
of precipitation, albiet low will be in close proximity to these
surface features. Heights aloft begin to rise a bit on Sunday as
ridging aloft begins building in from the west. In concert the
front will start a northward return, particularilly across the
central Plains and into western and southern MO. The front will
continue a slow northward retreat Sunday night-Monday-Monday
night, becoming increasingly north-south oriented. The threat of
precipitation should really ramp-up during this time frame as a
series of weak northwest flow disturbances traverse the area, and
as a west-southwesterly LLJ becomes established providing
increasing lift along and north/east of the boundary.

The boundary will lift well to the northeast by Tuesday with the
ridge aloft expanding through the MS Valley and into the Great
Lakes Tuesday-Thursday. The associated return of heat and humidity
is forecast to produce peak heat indices in the 100-105 range.

Glass

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1143 PM CDT Thu Jul 28 2016

Weak front/trof sliding south through forecast area, so still
seeing some isolated storms developing, mainly south of I-70. Kept
tafs dry for now. Otherwise, vfr conditions to prevail, except for
some patchy fog possible, mainly in river valleys, so kept mention
at KUIN, KSUS and KCPS between 08z and 12z Friday. Light northwest
winds to back to the west northwest by mid morning and pickup a
bit. Then winds to diminish once again towards sunset Friday
evening.

SPECIFICS FOR KSTL:
Weak front/trof sliding south through forecast area, so still
seeing some isolated storms developing, mainly south of I-70. Kept
tafs dry for now. Otherwise, vfr conditions to prevail, except for
some patchy fog possible, mainly in river valleys, so kept mention
at KSUS and KCPS between 08z and 12z Friday. Light north winds to
back to the west northwest by 15z Friday and pickup a bit. Then
winds to diminish once again towards sunset Friday evening.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



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