Hail and Damaging Winds in Iowa, May 14, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
242 PM CDT MON MAY 14 2007

.SHORT TERM...THROUGH THURSDAY

FORECAST CONCERNS ARE WITH THE RAIN CHANCES TONIGHT AND TUESDAY AND
THEN AGAIN FOR WEDNESDAY AFTERNOON.

SURFACE ANALYSIS THIS AFTERNOON SHOWS AN AREA OF LOW PRESSURE
SOUTHEAST OF KBJI IN NORTH CENTRAL MINNESOTA. COLD FRONT EXTENDED
SOUTHWEST FROM THE LOW INTO WESTERN KANSAS. REGIONAL RADARS SHOWING
A THIN LINE OF SHOWERS FROM CENTRAL MINNESOTA INTO SOUTH DAKOTA
BEHIND THE FRONT.

12Z MODELS ARE PRESENTING SIMILAR SOLUTIONS BUT THE NAM SHOWS
BETTER RUN TO RUN CONTINUITY THAN THE GFS AND HAS BETTER SUPPORT
FROM THE OTHER MODELS SO HAVE LEANED TOWARD THIS MODEL.

UPPER LEVEL TROUGH COMING ACROSS THE NORTHERN ROCKIES THIS AFTERNOON
WILL PROGRESS EASTWARD WITH A LEAD SHORT WAVE TROUGH EJECTING OUT
ACROSS THE GREAT LAKES REGION TONIGHT. THIS WILL PUSH THE COLD
FRONT INTO THE FORECAST AREA THIS EVENING. THE WHOLE SYSTEM HAS A
POSITIVE TILT LEADING TO THE BEST FORCING ARRIVING JUST BEHIND THE
SURFACE FRONT. THE BEST PV ADVECTION IN THE 500-300 MB LAYER WILL
COME ACROSS THE REGION LATE TONIGHT AND TUESDAY MORNING.
AGEOSTROPHIC MOTIONS FROM THE UPPER LEVEL JET WILL BE MAXIMIZED
LATE TONIGHT AND EARLY TUESDAY MORNING AS THE AREA COMES UNDER THE
ENTRANCE REGION OF THE JET. A BAND OF LOW LEVEL FRONTOGENESIS WILL
SET UP ACROSS THE REGION TONIGHT BEHIND THE FRONT IN THE 1000-850
MB LAYER. THE FORCING IS NOT ALL THAT STRONG SO SOMEWHAT CONCERNED
THAT THE ACTIVITY THAT DEVELOPS MAY END UP BEING MORE SCATTERED IN
NATURE...BUT HAVE MAINTAINED THE LIKELY POPS AS BOTH THE SPC WRF
AND ARW WRF FROM 00Z/13 SUPPORTED THE SOLUTIONS OF THE 12Z
OPERATIONAL RUNS. CAPE AXIS IS EXPECTED TO REMAIN ACROSS THE
FORECAST AREA THROUGH THE NIGHT WITH THE NAM SHOWING A NARROW RIBBON
OF UP TO 1000 J/KG STILL PRESENT ACROSS THE EAST AT 09Z. VERY
LITTLE CIN DEVELOPS OVERNIGHT SO STORMS HAVE THE POTENTIAL TO REMAIN
SURFACE BASED THROUGH THE NIGHT. THE BEST SHEAR IS IN THE 0-3 KM
LAYER BUT IS RATHER WEAK BETWEEN 20 AND 25 KNOTS FOR MUCH OF THE
NIGHT. HOWEVER...LATE TONIGHT...THE NAM SHOWS AROUND 40 KNOTS
DEVELOPING ACROSS THE FAR EASTERN SECTIONS. ANY SEVERE THREATS
SHOULD BE LARGE HAIL AND DAMAGING WINDS.

THE WHOLE SYSTEM SLOWS DOWN TUESDAY AS A PIECE OF ENERGY BREAKS OFF
OF THE HUDSON BAY UPPER LEVEL LOW AND DROPS INTO THE TROUGH AXIS. AS
A RESULT...THE UPPER LEVEL TROUGH AXIS STILL WILL NOT HAVE CLEARED
THE AREA BY 00Z WEDNESDAY. THERE IS STILL A BAND OF WEAK
FRONTOGENESIS OVER THE AREA IN THE 850-500 MB LAYER THROUGH THE DAY.
THE BEST FORCING AHEAD OF THE UPPER LEVEL TROUGH WILL BE LIMITED TO
THE EASTERN PART OF THE FORECAST AREA AND MAINTAINED THE LIKELY POPS
FOR TUESDAY MORNING FOR THE AREA EAST OF AN OELWEIN TO MAUSTON LINE.
COULD STILL BE SOME LINGERING SHOWERS DURING THE AFTERNOON OVER THIS
SAME AREA SO KEPT THE LOW CHANCE POPS GOING.

THE SHORT WAVE TROUGH THAT DROPS INTO THE LONG WAVE TROUGH WILL
FINALLY WORK ACROSS THE GREAT LAKES REGION WEDNESDAY. TEMPERATURES AT
500 MB ARE SHOWN BY THE NAM TO DROP TO -25C OR COLDER AS THE COLD
POOL ALOFT COMES ACROSS. THIS SETS UP LAPSE RATES OF 7 C/KM UP
THROUGH 500 MB FOR CENTRAL WISCONSIN AND FEEL THIS IS ENOUGH TO
SUPPORT THE POSSIBILITY OF SOME SHOWERS FOR THE NORTHEAST PART OF THE
STATE. THE NAM BUFKIT SOUNDING FOR KCWA EVEN SHOWS A LITTLE CAPE BUT
VALUES OF LESS THAN 100 J/KG. ONLY ADDED SHOWERS FOR NOW...BUT LATER
SHIFTS MAY HAVE TO ADD SOME ISOLATED THUNDER IF THE CAPE SIGNAL
REMAINS CONSISTENT.

.LONG TERM...THURSDAY THROUGH MONDAY

LATEST SET OF MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT THROUGH
THE PERIOD. HIGH PRESSURE AT THE SURFACE EXPECTED TO BE OVER THE
AREA EARLY IN THE PERIOD AND THEN SHIFT SOUTHEAST. MODELS ALL SHOW A
BACK DOOR COLD FRONT COMING INTO THE AREA SATURDAY AND SATURDAY
NIGHT. THE CONCERN WITH THIS FRONT WILL BE HOW FAR SOUTH IT WILL
MAKE IT BEFORE RETURNING TO THE NORTH AS A WARM FRONT EARLY NEXT
WEEK. WITH ALL THE MODELS SHOWING THE FRONT APPROACHING THE AREA OR
BEING IN THE AREA BY SATURDAY...ADDED SOME LOW CHANCE POPS IN FOR
THIS PERIOD ACROSS THE NORTHERN PART OF THE FORECAST AREA. THE
ECMWF AND THE DGEX ARE SLOWER TO LIFT THE FRONT BACK NORTH THAN THE
OPERATIONAL RUN OF THE GFS. THESE MODELS WOULD SUGGEST THE FRONT
WILL NOT LIFT BACK NORTH UNTIL MONDAY ONCE THE NEXT SYSTEM
APPROACHING FROM THE WEST STARTS TO DEEPEN. WILL KEEP SOME LOW
CHANCE POPS GOING ACROSS THE NORTH IN THE EVENT THE FRONT DOES MAKE
IT AS FAR SOUTH AS THE ECMWF SHOWS. ALSO LOWERED SOME DAYTIME HIGHS
FOR THE UPCOMING WEEKEND ANTICIPATING THE FRONT WITH SOME CLOUDS TO
BE IN THE AREA.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MNZ086-MNZ087-
     MNZ094-MNZ095.

IA...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ008-IAZ009-
     IAZ010-IAZ018-IAZ019-IAZ029.

&&

04

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LA CROSSE WI
619 PM CDT MON MAY 14 2007

WIZ017-029-034-042>044-151100-
ADAMS-CLARK-JACKSON-JUNEAU-MONROE-TAYLOR-
619 PM CDT MON MAY 14 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF CENTRAL WISCONSIN.

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS WILL PASS THROUGH THE AREA THIS EVENING. A
COUPLE OF THESE THUNDERSTORMS MAY BECOME SEVERE THROUGH 10 PM...WITH
LARGE HAIL OR DAMAGING WIND...BUT WIDESPREAD SEVERE WEATHER IS NOT
ANTICIPATED. THUNDERSTORMS CHANCES WILL CONTINUE THROUGH THE REST OF
THE NIGHT...BUT THE SEVERE THREAT WILL DIMINISH WITH TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A FEW THUNDERSTORMS MAY LINGER INTO TUESDAY. HOWEVER NONE OF THESE
THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE. THUNDERSTORMS ARE AGAIN
POSSIBLE SATURDAY NIGHT...BUT IT IS TOO EARLY TO DETERMINE IF ANY OF
THESE STORMS WILL BE SEVERE.

PATCHY FROST MAY OCCUR AS A RESULT OF HIGH PRESSURE BUILDING INTO
THE AREA WEDNESDAY NIGHT...AS LOW TEMPERATURES ARE EXPECTED TO DROP
INTO THE 30S.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL MOST LIKELY NOT BE NEEDED THIS EVENING.
HOWEVER...SPOTTER GROUPS AND COORDINATORS WILL NEED TO MONITOR
THUNDERSTORMS IN THE EVENING FOR THE NEED FOR A LOCALIZED
DEPLOYMENT.

.EMERGENCY MANAGEMENT COORDINATION...

NO CALL IS SCHEDULED.

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ032-033-041-
053>055-061-151100-
ALLAMAKEE-BUFFALO-CHICKASAW-CLAYTON-CRAWFORD-DODGE-FAYETTE-FILLMORE-
FLOYD-GRANT-HOUSTON-HOWARD-LA CROSSE-MITCHELL-MOWER-OLMSTED-RICHLAND-
TREMPEALEAU-VERNON-WABASHA-WINNESHIEK-WINONA-
619 PM CDT MON MAY 14 2007

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

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS WILL PASS THROUGH THE AREA THIS EVENING. A
COUPLE OF THESE THUNDERSTORMS MAY BECOME SEVERE THROUGH MIDNIGHT...
WITH LARGE HAIL OR DAMAGING WIND...BUT WIDESPREAD SEVERE WEATHER IS
NOT ANTICIPATED. THUNDERSTORMS CHANCES WILL CONTINUE THROUGH THE REST
OF THE NIGHT...BUT THE SEVERE THREAT WILL DIMINISH WITH TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A FEW THUNDERSTORMS MAY LINGER INTO TUESDAY MORNING. HOWEVER NONE OF
THESE THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE. THUNDERSTORMS ARE
AGAIN POSSIBLE SATURDAY NIGHT...BUT IT IS TOO EARLY TO DETERMINE IF
ANY OF THESE STORMS WILL BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL MOST LIKELY NOT BE NEEDED THIS EVENING.
HOWEVER...SPOTTER GROUPS AND COORDINATORS WILL NEED TO MONITOR
THUNDERSTORMS IN THE EVENING FOR THE NEED FOR A LOCALIZED
DEPLOYMENT.

.EMERGENCY MANAGEMENT COORDINATION...

NO CALL IS SCHEDULED.

BINAU