Severe Thunderstorm Warning 24, NWS La Crosse, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
125 PM CDT WED MAY 24 2006

.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT

FORECAST WAS IN GOOD SHAPE OVERALL. PUT SOME TIME INTO THURSDAYS LOW
OVERHEAD BUT OTHERWISE TIME WAS SPENT WITH SEVERE RISK TODAY AND
ACTIVE WEATHER.

AT 18Z...A COMPLEX SURFACE WIND PATTERN WAS SEEN OVER THE FORECAST
AREA WITH WI IN SOUTHERLY FLOW...AND THE WESTERN AREA MIXING INTO
A SOUTHWEST FLOW. THE REAL FRONTAL BOUNDARY...AND COINCIDENT DRY
PUNCH VISIBLE ON GOES WATER VAPOR IMAGERY...APPEARS AS THE WEST WIND
SHIFT CLOSER TO I-35. THIS STRONG DRY REGION ON WATER VAPOR IS
MIXING DEWPOINTS DOWN INTO THE 30S AND 40S ACROSS NEB. ECHOES HAVE
BEGUN TO APPEAR N OF KONA...HOWEVER INSTABILITY IS ONLY 500J/KG OF
MLCAPE. RUC HAS A PRETTY GOOD HANDLE ON THE INSTABILITY AND CONTINUES
TO DEVELOP HIGHER VALUES OVER THE SOUTHERN FORECAST AREA AS THIS
ENTIRE AREA SHIFTS EAST INTO WI LATER THIS AFTERNOON. SHEAR PROFILES
ARE NOT IMPRESSIVE EXCEPT THE VERY SOUTH AND BELIEVE THAT WITH MOST
OF THE SHEAR IN THE 0-3KM LAYER...WE ARE STILL MAINLY GOING TO SEE
PULSE AND MULTICELLS FORMING INTO A LINE AS THE COLD POOLS COALESCE.
DEEP MIXING IS ACTUALLY DECREASING THE SHEAR SOMEWHAT AND HODOGRAPH
LENGTHS ARE SHRINKING OVER THE PAST 2 HOURS. THE 18Z DVN
HODOGRAPH APPEARS A BIT MORE SUPERCELLULAR WITH DEEP SHEAR AND
A LONGER HODOGRAPH. HOWEVER...THE BLUE RIVER PROFILE IS LESS
FAVORABLE. SO...THE HIGHER THREAT FROM A WIND SHEAR PERSPECTIVE SEEMS
FURTHER SOUTH /SWRN WI/. EXPECT THE INSTABILITY TO GROW AND TSRA TO
FORM ON THE RIVER OR EAST THIS AFTERNOON AND EXIT QUICKLY...BY LATE
AFTERNOON /6PM/.

24.12Z NAM AND GFS SOLUTIONS ARE FAIRLY CLOSE THROUGH EARLY FRIDAY
WITH NO MAJOR DIFFERENCES TO NOTE. TONIGHT THE FRONT WILL
SCOUR THE REAL INSTABILITY EAST AND THE FORECAST AREA WILL STABILIZE
MORE WITH A PERIOD OF EVENING CLEARING BEFORE DEEPER DAKOTAS LOW
MOISTURE MOVES IN. WIDESPREAD CLOUDS AND SHOWERS ARE EXPECTED
THURSDAY UNDER THE INFLUENCE OF THE TROPOSPHERIC DEEP LOW. HAVE GONE
TO A COVERAGE IN THE GRIDS OF OCNL SHRA WITH ISOLATED THUNDER. WHILE
THUNDER SHOULD NOT BE A LARGE PROBLEM...MLCAPES IN THE 200-500 J/KG
RANGE WILL STILL PRESENT A RISK OF LIGHTNING.

AS THE LOW SHIFTS EAST ACROSS WI LATE THURSDAY NIGHT...SOME MODEL
DIFFERENCES PRESENT THEMSELVES IN HOW THE CLOUDS WILL SHIFT EAST
WITH THE 24.12Z GFS BEING QUITE SLOW. WITH THURSDAYS RAINFALL
/TENTH OR TWO/ AND LINGERING DEWPOINTS IN THE 55 TO 60F RANGE WITH
WEAK SURFACE ADVECTIONS...SEEMS A STRATUS OR STRATOCUMULUS COVERAGE
ON FRIDAY MAY OCCUR. HAVE INCREASED A BIT MORE ON CLOUDS BUT STILL
KEPT ONLY AROUND 55 PERCENT IN WI DRYING WESTWARD SOME.

OTHERWISE...24.12Z GFS SOLUTION IS CONSISTENT WITH ITS PAST RUNS IN
WANTING TO PULL A WARM FRONTAL FEATURE THROUGH ON SATURDAY
AFTERNOON. WITH STABLE SURFACE CONVECTIVE INHIBITIONS OF 200-400
J/KG...THE WEATHER WOULD HAVE TO BE ELEVATED ACCAS DEVELOPMENT AND
VERY LIGHT SHOWERS/VIRGA ON THE NOSE OF 800-850MB CENTERED MOISTURE
TRANSPORT CONVERGENCE REGION SHIFTING THROUGH. WITH THIS BEING SUCH A
LOW PROBABILITY...HAVE CONTINUED THE PREVIOUS FORECAST FOR SATURDAY.

WELCOME TO SUMMER.

.LONG TERM...SUNDAY THROUGH TUESDAY

THE TRENDS IN THE EXTENDED MODELS CONTINUE TO SLOWLY MOVE THE 500 MB
RIDGE EAST THIS WEEKEND...WITH THE RIDGE AXIS SHIFTING OVER THE
EASTERN HALF OF THE U.S. BY EARLY NEXT WEEK. AT THE SFC...A COLD
FRONT WILL TRACK INTO THE REGION LATE MONDAY INTO TUESDAY...AND
SHOULD FIRE SHOWERS/STORMS ALONG AND AHEAD OF IT. GOOD INSTABILITY
IS ALREADY PROGGED AHEAD OF THIS FRONT...BUT THE BETTER WIND SHEAR
IS WELL BEHIND THE FRONT. THE FRONT COULD BRING A DECENT SHOT FOR
SOME SEVERE WEATHER...BUT MUCH DEPENDS ON THE TIMING OF THE FRONT.
THE SHORTWAVE TROUGH RESPONSIBLE FOR THE SFC FRONT WILL MOVE EAST
NORTHEAST THROUGH WHAT/S LEFT OF THE RIDGE...CHANGING THE FLOW FROM
SOUTHWEST TO MORE ZONAL. THE WARM TEMPERATURES FROM THIS WEEKEND
SHOULD THEREFORE MODERATE BACK TO THE MORE SEASONABLE LEVELS.

RIECK
&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.

&&

BAUMGARDT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
452 PM CDT WED MAY 24 2006

WIZ017-029-033-034-041>044-053>055-061-250300-
ADAMS-CLARK-CRAWFORD-GRANT-JACKSON-JUNEAU-LA CROSSE-MONROE-RICHLAND-
TAYLOR-TREMPEALEAU-VERNON-
452 PM CDT WED MAY 24 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF CENTRAL AND SOUTHWEST
WISCONSIN.

.DAY ONE...TONIGHT

A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED THROUGH 10 PM. THE
ACTIVITY WILL LAST THROUGH ABOUT 6 PM EAST OF AN EAU CLAIRE TO
SPARTA...TO VIROQUA...TO DUBUQUE LINE.

A COLD FRONT MOVING THROUGH HAS TRIGGERED TWO LINES OF THUNDERSTORMS
VERY CLOSE TO EACH OTHER. THESE LINE WILL CONTINUE TO SHIFT EAST
THROUGH THE VERY EARLY EVENING AND WILL HAVE THE POTENTIAL TO PRODUCE
LARGE HAIL AND DAMAGING WINDS. THE LINE OF STORMS IS EXPECTED TO
SHIFT TO THE I-39/51 CORRIDOR IN CENTRAL WISCONSIN...TO DODGEVILLE
IN SOUTHWEST WISCONSIN...BY 7 PM. THIS WILL END THE SEVERE
THUNDERSTORM THREAT FROM WEST TO EAST IN WISCONSIN.

IN SOUTHWEST WISCONSIN THERE IS AN ADDITIONAL SMALL THREAT FOR
BRIEF TORNADO DEVELOPMENT AS WELL BUT WIND FIELDS WILL HAVE TO COME
TOGETHER JUST RIGHT FOR THAT TO OCCUR.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORM CHANCES WILL CONTINUE THURSDAY AND THURSDAY EVENING AS
THIS STORM SYSTEM DRIFTS OVER AND EAST OF THE AREA. THESE STORMS ARE
EXPECTED TO BE MORE ISOLATED IN NATURE AND REMAIN BELOW SEVERE
LEVELS.

ANOTHER SYSTEM WILL AFFECT THE AREA EARLY NEXT WEEK WITH ANOTHER
CHANCE OF THUNDERSTORMS MEMORIAL DAY AND TUESDAY. AT THIS TIME IT IS
TOO EARLY TO DETERMINE IF THESE STORMS WILL BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS WILL BE NEEDED ALONG THE LINE OF THUNDERSTORMS...IN
WISCONSIN...THROUGH 6 PM. ACTIVATE BEFORE STORMS AFFECT YOUR
COMMUNITIES.

.EMERGENCY MANAGEMENT COORDINATION...

NO CALL IS SCHEDULED. PLEASE ENSURE YOUR SPOTTER GROUPS ARE PREPARED
TO REPORT PEAK WIND GUSTS OBSERVED IN THEIR COMMUNITIES THIS
AFTERNOON.

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ032-250300-
ALLAMAKEE-BUFFALO-CHICKASAW-CLAYTON-DODGE-FAYETTE-FILLMORE-FLOYD-
HOUSTON-HOWARD-MITCHELL-MOWER-OLMSTED-WABASHA-WINNESHIEK-WINONA-
452 PM CDT WED MAY 24 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF WESTERN WISCONSIN...
NORTHEAST IOWA...AND SOUTHEAST MINNESOTA.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORM CHANCES WILL CONTINUE THURSDAY AND THURSDAY EVENING AS
THIS STORM SYSTEM DRIFTS OVER AND EAST OF THE AREA. THESE STORMS ARE
EXPECTED TO BE MORE ISOLATED IN NATURE AND REMAIN BELOW SEVERE
LEVELS.

ANOTHER SYSTEM WILL AFFECT THE AREA EARLY NEXT WEEK WITH ANOTHER
CHANCE OF THUNDERSTORMS MEMORIAL DAY AND TUESDAY. AT THIS TIME IT IS
TOO EARLY TO DETERMINE IF THESE STORMS WILL BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.

.EMERGENCY MANAGEMENT COORDINATION...

NO CALL IS SCHEDULED.

BAUMGARDT