Hail and Damaging Winds in Iowa, September 13, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
255 AM CDT TUE SEP 13 2005

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

MAIN FORECAST CONCERNS WILL BE SHOWER/THUNDERSTORM CHANCES
TODAY/TONIGHT...AND AGAIN ON THURSDAY.

DATA ANALYSIS AT 2 AM DEPICTED A SURFACE COLD FRONT EXTENDING FROM
NORTHWEST WI...THROUGH SOUTHWEST MN AND INTO EASTERN NEB. EMBEDDED
SHORTWAVE TROUGH IN SOUTHWEST FLOW ALOFT (EVIDENT ON WATER VAPOR
SATELLITE LOOP) WAS KICKING OFF SCATTERED CONVECTION...SOME
STRONG...FROM NORTHWEST IA...THROUGH SOUTHERN MN...INTO NORTHWEST
HALF OF WI.

00Z 13SEP05 MODEL RUN SHOWS NAM INITIALIZING BETTER THEN THE GFS
WITH REGARD TO CURRENT CONVECTION. BEYOND THIS...APPEARS BOTH
MODELS IN DECENT AGREEMENT WITH THEIR MASS FIELDS UNTIL THURSDAY
NIGHT.

FOR TODAY...UPPER LEVEL TROUGH CONTINUES TO MOVE EAST INTO THE
NORTHERN PLAINS...PUSHING THE SURFACE COLD FRONT INTO CENTRAL WI BY
THIS EVENING. NAM SHOWS BEST MOISTURE TRANSPORT/SURFACE HEATING...AND
RESULTANT SURFACE BASED CAPE WILL BE EAST OF THE FORECAST AREA
ALREADY BY EARLY AFTERNOON. HOWEVER...LIFT ALONG THE FRONT AIDED WITH COOLING
ALOFT ASSOCIATED WITH APPROACHING OF UPPER LEVEL TROUGH/FAVORED
RIGHT ENTRANCE REGION OF 300MB JETLET/APPROACHING EMBEDDED MID LEVEL
SHORTWAVE FROM CENTRAL PLAINS...SHOULD ALL COME TOGETHER FOR
REDEVELOPMENT OF CONVECTION TODAY. WILL MAINTAIN THE LIKELY CHANCES
CURRENTLY IN THE GRID DATA BASE.

THE COLD FRONT FRONT REMAINS PROGRESSIVE...PUSHING WELL EAST OF THE
AREA BY MIDNIGHT...TAKING THE RAIN CHANCES WITH IT. HIGH PRESSURE
BUILDS INTO THE AREA...PROVIDING CLEARING CONDITIONS ACROSS THE AREA
LATER IN THE NIGHT. CLEARING SKIES...RECENT RAINFALL...AND LIGHT
WINDS WILL THEN LIKELY LEAD TO SOME RIVER VALLEY FOG. WILL INCLUDE
THIS IN THE WEATHER GRID FOR LATE TONIGHT INTO EARLY MORNING HOURS
WEDNESDAY. THE HIGH CONTINUES AND SETTLES ACROSS THE AREA ON
WEDNESDAY FOR QUIET AND SEASONABLY COOLER CONDITIONS. THE HIGH
ALREADY BUDGES EAST OF THE AREA BY WEDNESDAY NIGHT AS A MID LEVEL
SHORTWAVE TROUGH AND SURFACE LOW MOVE EAST ACROSS SOUTHERN
CANADA/NORTHERN PLAINS. APPEARS THAT THE MODELS ARE TAKING THE WAVE
A BIT MORE NORTH THAN PREVIOUS RUNS...PLACING MOST OF THE ASSOCIATED
FORCING NORTH OF THE FORECAST AREA ON THURSDAY. WILL HOWEVER
MAINTAIN A SMALL CHANCE OF SHRA/TS ACROSS WESTERN AND NORTHERN
PERIPHERY OF THE FORECAST AREA WHICH WILL REMAIN ON THE EASTERN EDGE
OF WEAK TO MODERATE MOISTURE TRANSPORT BETWEEN 850 AND 925MB.

NAM AND GFS DIFFER THURSDAY NIGHT TIME FRAME. THE NAM TAKES THE COLD
FRONT FROM THE SOUTHERN CANADIAN LOW SOUTHEAST ACROSS THE AREA WITH
LIGHT QPF. MEANWHILE...THE GFS WANTS TO LIFT THE BOUNDARY BACK NORTH
AS A WARM FRONT IN ADVANCE OF A NEW WAVE OF LOW PRESSURE ACROSS THE
NORTHERN PLAINS. IT ALSO SHOWS NO PRECIPITATION. WILL TAKE A
COMPROMISE HERE AND INCREASE THE CLOUDS ACROSS THE AREA...BUT WILL
LEAVE DRY FOR NOW.

.LONG TERM...FRIDAY THROUGH MONDAY

00Z 13SEP05 GFS CONTINUING TO SHOW A PROGRESSIVE PATTERN THROUGH THE
PERIOD AS FLOW REMAINS FAIRLY HIGH ZONAL. PRETTY STRONG CYCLOGENESIS
TAKES PLACE OVER WESTERN NEBRASKA SATURDAY NIGHT. THE LOW THEN
TRACKS QUICKLY NORTHEAST TOWARD THE UPPER MIDWEST ON
SUNDAY...SPREADING SHOWER/THUNDERSTORM CHANCES ACROSS THE AREA.
GRIDS HAVE THIS HANDLED WELL...SO NO CHANGES MADE.

&&

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

DAS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
1215 PM CDT TUE SEP 13 2005

MNZ079-086>088-094>096-WIZ017-029-032>034-041>044-053-141000-
ADAMS-BUFFALO-CLARK-DODGE-FILLMORE-HOUSTON-JACKSON-JUNEAU-LA CROSSE-
MONROE-MOWER-OLMSTED-TAYLOR-TREMPEALEAU-VERNON-WABASHA-WINONA-
1215 PM CDT TUE SEP 13 2005

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

A COLD FRONT WILL TRACK SLOWLY ACROSS THE REGION THIS AFTERNOON...
EXITING INTO EASTERN WISCONSIN THIS EVENING. TO THE SOUTHWEST...AN
UPPER LEVEL DISTURBANCE WILL SPIN NORTHEAST AHEAD OF THE FRONT...
TRACKING ACROSS SOUTHEAST WISCONSIN ALSO DURING THE EVENING HOURS.
THESE WEATHER FEATURES WILL WORK ON THE INCREASING INSTABILITY
ACROSS THE REGION TO TRIGGER THUNDERSTORMS THIS AFTERNOON AND
EVENING. CURRENTLY...THE MORE FAVORABLE SEVERE WEATHER PARAMETERS
WILL BE LOCATED TO THE SOUTH ACROSS NORTHEAST IOWA AND SOUTHWEST
WISCONSIN. HOWEVER...AN ISOLATED SEVERE THUNDERSTORM CANNOT BE RULED
OUT...MOSTLY SOUTH OF A ROCHESTER TO LA CROSSE TO NECEDAH LINE.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE NEXT CHANCE FOR THUNDERSTORMS WILL COME THURSDAY AS ANOTHER WEAK
DISTURBANCE MOVES ACROSS SOUTHERN CANADA. THE BEST CHANCE FOR RAIN
WILL BE NORTH OF A LINE FROM AUSTIN AND WINONA MINNESOTA...TO
NEILLSVILLE WISCONSIN. IT DOES NOT APPEAR AT THIS TIME THAT ANY OF
THESE STORMS WILL BECOME SEVERE.  THUNDERSTORMS ARE ALSO POSSIBLE
ON SUNDAY...BUT IT IS TOO EARLY TO DETERMINE IF SEVERE WEATHER WILL
OCCUR.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION COULD BE NEEDED THIS AFTERNOON AND EARLY THIS
EVENING...MAINLY SOUTH OF A ROCHESTER TO LA CROSSE TO NECEDAH LINE.
SPOTTER GROUPS SHOULD STAY ABREAST FOR THIS POSSIBILITY...AND BE
PREPARED TO DEPLOY IF THE SEVERE THREAT INCREASES. THE MOST LIKELY
TIMES WILL BE BETWEEN 2 AND 5 PM.

.EMERGENCY MANAGEMENT COORDINATION...

NO CALL IS SCHEDULED.

IAZ008>011-018-019-029-030-WIZ054-055-061-141000-
ALLAMAKEE-CHICKASAW-CLAYTON-CRAWFORD-FAYETTE-FLOYD-GRANT-HOWARD-
MITCHELL-RICHLAND-WINNESHIEK-
1215 PM CDT TUE SEP 13 2005

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

A COLD FRONT WILL TRACK SLOWLY ACROSS THE REGION THIS AFTERNOON...
EXITING INTO EASTERN WISCONSIN THIS EVENING. TO THE SOUTHWEST...AN
UPPER LEVEL DISTURBANCE WILL SPIN NORTHEAST AHEAD OF THE FRONT...
TRACKING ACROSS SOUTHEAST WISCONSIN ALSO DURING THE EVENING HOURS.
THESE WEATHER FEATURES WILL WORK ON THE INCREASING INSTABILITY
ACROSS THE REGION TO TRIGGER THUNDERSTORMS THIS AFTERNOON AND
EVENING. THE INSTABILITY AND WIND PROFILES WILL FAVOR SEVERE
THUNDERSTORM DEVELOPMENT...WITH ISOLATED SUPERCELLS ALSO POSSIBLE.
THE MAIN THREATS WILL BE LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE NEXT CHANCE FOR THUNDERSTORMS WILL COME THURSDAY AS ANOTHER WEAK
DISTURBANCE MOVES ACROSS SOUTHERN CANADA. THE BEST CHANCE FOR RAIN
WILL BE NORTH OF A LINE FROM AUSTIN AND WINONA MINNESOTA...TO
NEILLSVILLE WISCONSIN. IT DOES NOT APPEAR AT THIS TIME THAT ANY OF
THESE STORMS WILL BECOME SEVERE.  THUNDERSTORMS ARE ALSO POSSIBLE
ON SUNDAY...BUT IT IS TOO EARLY TO DETERMINE IF SEVERE WEATHER WILL
OCCUR.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED AT TIMES THIS AFTERNOON AND EARLY
THIS EVENING. SPOTTER GROUPS SHOULD BE PREPARED TO DEPLOY AS
THUNDERSTORMS APPROACH THEIR AREA. THE MOST LIKELY TIMES WILL BE
BETWEEN 2 AND 5 PM.

.EMERGENCY MANAGEMENT COORDINATION...

NO CALL IS SCHEDULED.

RIECK

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
1153 AM CDT TUE SEP 13 2005

IAZ008>011-018-019-029-030-WIZ054-055-061-140000-
ALLAMAKEE-CHICKASAW-CLAYTON-CRAWFORD-FAYETTE-FLOYD-GRANT-HOWARD-MITCHELL-
RICHLAND-WINNESHIEK

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH
781 IN EFFECT UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING AREAS

IN IOWA THIS WATCH INCLUDES 8 COUNTIES

IN NORTH CENTRAL IOWA

FLOYD                 MITCHELL

IN NORTHEAST IOWA

ALLAMAKEE             CHICKASAW             CLAYTON
FAYETTE               HOWARD                WINNESHIEK

IN WISCONSIN THIS WATCH INCLUDES 3 COUNTIES

IN SOUTHWEST WISCONSIN

CRAWFORD              GRANT                 RICHLAND

THIS INCLUDES THE CITIES OF...CHARLES CITY...CRESCO...DECORAH...
ELKADER...NEW HAMPTON...OELWEIN...OSAGE...PLATTEVILLE...
PRAIRIE DU CHIEN...RICHLAND CENTER AND WAUKON.