Flash Flooding in Wisconsin, July 6, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
250 AM CDT SAT JUL 6 2002

07/06Z SUBJECTIVE ANALYSIS SHOWING A SLOW MOVING WARM FRONT
EXTENDING FROM ABOUT KSTC-KDEH-KMLI.  ONCE AGAIN...CONVECTION
DEVELOPED ALONG THIS FEATURE DURING THE DAY...ISOLATED IN NATURE.
OVERNIGHT...THIS HAS CONTINUED.  SATELLITE SHOWING CLOUD DEVELOPMENT
OCCURRING NORTHEAST OF THE BOUNDARY ALONG MOST OF ITS EXTENT.
ACROSS THE HIGH PLAINS...A COLD FRONT CONTINUES TO MOVE TOWARD THE
REGION.  MAIN FORECAST CHALLENGE IS RESOLVING WHAT THE CONVECTIVE
POTENTIAL IS AS THE WEAK WARM FRONT MOVES THROUGH THE FORECAST
AREA.  ALSO...DETERMINING WHAT INFLUENCE THE COLD FRONT WILL HAVE ON
THE FORECAST AREA.

06/03Z RUC SHOWING THE CONVECTION ACROSS NORTHEAST IOWA REDEVELOPING
ACROSS SOUTHERN WISCONSIN.  THIS HAS OCCURRED NEARLY AS FORECAST BY
THE MODEL.  06/06Z RUC CONTINUES THE CONVECTION IN THAT VICINITY BUT
ALSO SPREADS IT NORTH.  AM SKEPTICAL OF THIS AT THIS TIME GIVEN THE
LOW DEWPOINTS TO THE NORTH OF THIS SYSTEM.  HOWEVER...WILL WAIT TO
ISSUE ZONES TO ATTEMPT TO CAPTURE WHAT WILL HAPPEN.

MODELS IN GENERAL AGREEMENT THROUGH T+24HR.  CAPES BUILD IN THE
VICINITY OF THE SLOW MOVING WARM FRONT...2500 J/KG BY AFTERNOON.
THIS IS MORE UNSTABLE THAN PREVIOUS DAYS...THEREFORE THINK A HIGHER
CHANCE OF THUNDERSTORMS REMAINS WARRANTED.  THIS ACTIVITY SHOULD BE
MAINLY DIURNAL...BUT COULD PERSIST ON A LESSER SCALE OVERNIGHT AS
HAS BEEN THE CASE OVER THE PAST FEW DAYS.

OVERNIGHT...THE FRONT MOVES SOUTH INTO THE REGION.  THE QUESTION
IS...HOW FAR SOUTH WILL IT GET.  AT THE SURFACE...NEITHER MODEL
PUSHES IT THROUGH THE FORECAST AREA.  HOWEVER...THE ETA MOVES A 850
MB TROUGH THROUGH THE FORECAST AREA...WHILE THE AVN STALLS THIS
SAME FEATURE ACROSS THE NORTHERN COUNTIES IN THE FORECAST AREA.  LOW
CONFIDENCE IN THIS PORTION OF THE FORECAST.  HOWEVER...NO
MATTER WHICH MODEL IS FAVORED...THERE REMAINS A CHANCE OF
THUNDERSTORMS ACROSS THE FORECAST AREA.  AVN WOULD FAVOR THE BEST
CHANCES ALONG THE NORTHERN COUNTIES...WHILE THE ETA WOULD FAVOR THE
SOUTHERN COUNTIES.  WILL CONTINUE A CHANCE ACROSS THE ENTIRE
FORECAST AREA AT THIS TIME GIVEN THE AMOUNT OF UNCERTAINTY.

ON SUNDAY...RESIDUAL LOW LEVEL TROUGH IN CONJUNCTION WITH OTHER LEFT
OVER BOUNDARIES AND ANY CONVECTIVELY INDUCED VORTS (MCV/S) WILL
ENHANCE THE CONVECTIVE POTENTIAL SUNDAY...AS WILL THE CAPES
EXCEEDING 4000 J/KG DURING THE AFTERNOON.  EXACTLY WHERE THIS WILL
OCCUR IS TOO DIFFICULT TO PIN POINT AT THIS TIME.  THUS...WILL
CONTINUE CHANCE OF THUNDERSTORMS ALL AREAS SUNDAY AND INTO SUNDAY
NIGHT.  THIS SAME SCENARIO WILL CONTINUE INTO MONDAY AS WELL.
EXPECT THAT SUBSEQUENT SHIFTS WILL NARROW FORECAST PRECIPITATION
CHANCES AS SITUATION BECOMES MORE CLEAR.

.LSE...NONE.

KRC

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-062200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
445 AM CDT SAT JUL 6 2002

HAZARD - SCATTERED THUNDERSTORMS.

TIMING - MAINLY THIS AFTERNOON THROUGH TONIGHT.

LOCATION - PARTS OF WESTERN AND SOUTHWEST WISCONSIN...SOUTHEAST
MINNESOTA AND NORTHEAST IOWA.

DISCUSSION - A FRONTAL BOUNDARY WILL CONTINUE TO WAVER OVER THE
UPPER MISSISSIPPI RIVER VALLEY TODAY. SURFACE TEMPERATURES AND
MOISTURE WILL BE ON THE INCREASE...ADDING TO THE INSTABILITY OF THE
ATMOSPHERE. THE AFTERNOON SUN WILL WORK ON THE DESTABILIZATION WHILE
THE BOUNDARY SERVES AS THE MAIN FOCUS FOR STORM DEVELOPMENT. THE
BEST CHANCES WILL LIKELY BE ACROSS NORTHEAST IOWA. SMALL HAIL AND
GUSTY WINDS WILL BE POSSIBLE WITH THE STORMS THAT DO
DEVELOP...ALTHOUGH THEY ARE NOT ANTICIPATED TO REACH SEVERE LIMITS
AT THIS TIME.

SCATTERED THUNDERSTORMS THIS MORNING HAVE DEVELOPED ALONG A LOW
LEVEL BOUNDARY...AND WILL PERSIST THROUGH THE MID MORNING HOURS.
SOME SMALL HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS...BUT NONE
ARE EXPECTED TO BECOME SEVERE. THE ACTIVITY WILL BE CONFINED
MOSTLY TO WESTERN AND SOUTHWEST WISCONSIN.

SPOTTER INFORMATION - SPOTTER ACTIVATION IS NOT ANTICIPATED.

RIECK