Severe Thunderstorm Warning 147, NWS La Crosse, WI

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LA CROSSE WI
140 PM CDT SAT AUG 23 1997

OBVIOUS FORECAST PROBLEM REVOLVES AROUND ANTICIPATED EVENING
THUNDERSTORM EPISODE.

MOST WEATHER PARAMETERS ARE IN PLACE FOR RAPIDLY DEVELOPING
THUNDERSTORMS LATER THIS AFTERNOON AND EVENING.  LATEST SURFACE RUC AND
HAND MESOANALYSIS DEPICTED WELL DEFINED WARM FRONT FROM GHW TO MCW. THE
AIRMASS WAS VERY UNSTABLE WEST OF THIS FRONT WITH LIFTED INDICIES
NEARING MINUS 10...WITH NEARLY CLOUD FREE SKIES. ANOTHER RAIN COOLED
BOUNDARY WAS FROM RGK TO DEH-EC IA...THANKS TO CONVECTION ONGOING/18Z/
OVER WC WI.  THIS ELEVATED CONVECTION BEING GENERATED BY ISENTROPIC
LIFT. WE ARE NOW WAITING FOR NEW CONVECTION TO FORM OVER CNTRL-SC MN.

CONVERGENCE WAS INCREASING ALONG THE AFOREMENTIONED WARM FRONT...WITH
THETA-E ADVECTION BULLSYED OVER SC MN INTO NC IA.  WITH UPPER LEVEL
DIVERGENCE INCREASING OVER THE SAME AREA...CAPES APPROACHING 2000 J/KG
AND HELICITIES OVER 200...WOULD ANTICIPATE RAPIDLY DEVELOPING
THUNDERSTORMS OVER THAT AREA BY LATE AFTERNOON. 12Z ETA HAD A GOOD
HANDLE ON THIS. WITH STRONG NW FLOW ALOFT...THE SCATTERED THUNDERSTORMS
SHOULD EVOLVE INTO A BOW ECHO/MESOSCALE CONVECTIVE COMPLEX/ BY MID
EVENING AND RACE SOUTHEAST ACROSS THE FORECAST AREA FROM 22-03Z.

OVERNIGHT...AFTER THE CONVECTION MOVES TO OUR SOUTH...MODELS HAVE
CLEARING SKIES AND WINDS GOING LIGHT. COULD HAVE SOME DENSE FOG PATCHES
LATE.

FOLLOWED NGM@ MOS GUIDANCE FOR OVERNIGHT LOWS.

RACY

CORRECTED BAD DATE

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-241200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
230 PM CDT SAT AUG 23 1997

...SEVERE WEATHER THREAT CONTINUES TO INCREASE...

THE POTENTIAL EXISTS FOR AN OUTBREAK OF SEVERE WEATHER LATE THIS
AFTERNOON INTO THE EVENING HOURS ACROSS ALL OF SOUTHEAST
MINNESOTA...NORTHEAST IOWA AND THE WESTERN PORTIONS OF WISCONSIN. THE
PRIMARY THREAT WILL BE LARGE HAIL AND DAMAGING WINDS. ISOLATED
TORNADOES ARE ALSO POSSIBLE.

AT MID AFTERNOON...A WARM FRONT WAS ENTERING SOUTHEAST MINNESOTA AND
NORTHEAST IOWA. VERY UNSTABLE AIR CONTINUED TO FEED UP INTO CENTRAL
MINNESOTA JUST BEHIND THIS FRONT. IT APPEARS THAT THUNDERSTORMS WILL
DEVELOP AFTER 4PM IN CENTRAL MINNESOTA AND DEVELOP/MOVE SOUTHEAST INTO
SOUTHEAST MINNESOTA AND WEST CENTRAL WISCONSIN AFTER 6PM. THESE
THUNDERSTORMS WILL THEN RACE SOUTHEAST ACROSS THE REMAINDER OF WESTERN
WISCONSIN AND NORTHEAST IOWA BETWEEN 6PM AND 11PM.

SPOTTER GROUPS AND LAW ENFORCEMENT OFFICIALS ARE ADVISED TO REMAIN ON
HIGH ALERT AS ACTIVATION WILL MOST LIKELY BE NEEDED AFTER 4PM.

RACY

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-240105-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
558 PM CDT SAT AUG 23 1997

...A TORNADO WATCH IS IN EFFECT FOR MOST OF THE AREA UNTIL 11PM...

THE TORNADO WATCH INCLUDES SOUTHEAST MINNESOTA AND MOST OF
NORTHEAST IOWA AND WESTERN WISCONSIN. THE ONLY COUNTIES NOT
INCLUDED IN THE TORNADO WATCH ARE ADAMS COUNTY WISCONSIN AND
MITCHELL AND FLOYD COUNTIES IN NORTHEAST IOWA.

THUNDERSTORMS CONTINUED TO DEVELOP RAPIDLY THIS EVENING...WITH THE
STRONGEST STORMS 20 MILES EAST OF AUSTIN MINNESOTA AND NEAR EAU
CLAIRE WISCONSIN. THE STORMS WERE MOVING SOUTH AND SOUTHEAST AT 25
MPH.

THUNDERSTORMS ARE GOING TO BECOME MORE NUMEROUS THIS EVENING. SOME
OF THE STORM MAY BECOME SEVERE WITH THE PRIMARY THREAT BEING LARGE
HAIL AND DAMAGING WINDS.  ISOLATED TORNADOES ARE ALSO POSSIBLE.

RACY