Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1143 PM CDT WED JUL 27 2016

.UPDATE...
Issued at 924 PM CDT Wed Jul 27 2016

Isolated-scattered thunderstorms are currently affecting portions
of northeast Missouri and west-central Illinois as of 0200 UTC. In
addition...a more organized region of rain and embedded storms is
just clipping portions of SE MO. Much like last night...anticipate
a weakening and lessening in coverage of current activity. Next
disturbance currently near the SD/NE border may help initiate more
activity late tonight and early on Thursday...particularly for
northern sections of the CWFA.

Gosselin

&&

.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.

Britt

.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
in.

Britt

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1132 PM CDT Wed Jul 27 2016

Isolated showers and thunderstorms may affect the terminals
tonight and into the day on Thursday. Low coverage and fairly
nebulous forcing makes pinning down if and when storms may affect
the terminals difficult to say the least...particuarly looking out
more than a few hours. Did add a VCTS group in for early in the
period. Continued mention of fog at KCOU and KUIN but with higher
cloud cover than previously forecast...do not have in for the
metro TAFs. Weak frontal wave will move through the area on
Thursday with a continued chance of showers/storms. Behind
this...should be slightly lesser chances of rain along with winds
becoming northwesterly.

SPECIFICS FOR KSTL:

Added a VCTS group due to isolated storms firing near the
terminal. Possibility exists pretty much through most of the TAF
period of convection affecting terminal. Heavier thundershowers
if they hit the terminal could bring brief periods of IFR visbys.
Outside of this possibility...site is expected to remain VFR along
with light/variable winds. Northwest winds are likely by late
Thursday behind a weak sfc low.

Gosselin

&&

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

WFO LSX

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAINT LOUIS MO
345 PM CDT WED JUL 27 2016

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-281200-
GREENE IL-MACOUPIN IL-MONTGOMERY IL-BOND IL-FAYETTE IL-CLINTON IL-
MARION IL-WASHINGTON IL-RANDOLPH IL-ADAMS IL-BROWN IL-PIKE IL-
CALHOUN IL-JERSEY IL-MADISON IL-SAINT CLAIR IL-MONROE IL-KNOX MO-
LEWIS MO-SHELBY MO-MARION MO-MONROE MO-RALLS MO-PIKE MO-BOONE MO-
AUDRAIN MO-MONITEAU MO-COLE MO-OSAGE MO-CALLAWAY MO-MONTGOMERY MO-
LINCOLN MO-GASCONADE MO-WARREN MO-SAINT CHARLES MO-FRANKLIN MO-
SAINT LOUIS MO-SAINT LOUIS CITY MO-JEFFERSON MO-CRAWFORD MO-
WASHINGTON MO-SAINT FRANCOIS MO-SAINTE GENEVIEVE MO-IRON MO-
MADISON MO-REYNOLDS MO-
345 PM CDT WED JUL 27 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND
CENTRAL MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

BRITT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
119 AM CDT THU JUL 28 2016

ILZ101-280715-
ST. CLAIR IL-
119 AM CDT THU JUL 28 2016

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ST. CLAIR COUNTY
UNTIL 215 AM CDT...

AT 119 AM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM OVER
ALORTON...MOVING SOUTHEAST AT 10 MPH.

NICKEL SIZE HAIL AND WINDS IN EXCESS OF 30 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
BELLEVILLE...O'FALLON...EAST ST. LOUIS...COLLINSVILLE...
FAIRVIEW HEIGHTS...CAHOKIA...SWANSEA...SHILOH...CENTREVILLE...
CASEYVILLE...WASHINGTON PARK...MADISON...FAIRMONT CITY...
ALORTON AND SAUGET.

THIS INCLUDES INTERSTATE 64 IN ILLINOIS BETWEEN EXITS 9 AND 14.

LAT...LON 3845 9003 3857 9022 3866 9014 3866 8997
      3863 8988
TIME...MOT...LOC 0619Z 300DEG 10KT 3860 9011

KANOFSKY