Severe Thunderstorm Warning 138, NWS Milwaukee, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
240 PM CDT MON SEP 11 2000

FORECAST CONCERN IS SEVERE WEATHER POTENTIAL AND FLASH FLOODING
TONIGHT.

FRONTAL BOUNDARY TO THE WEST SHOULD ACT AS A FOCUSING MECHANISM FOR
THUNDERSTORMS DEVELOPMENT LATER THIS AFTERNOON. STORMS SHOULD THEN
RACE OUT AHEAD OF THE FRONT AND MOVE THROUGH WISCONSIN. SPC GIVES
US A MODERATE RISK FOR SEVERE STORMS WHICH LOOKS REASONABLE. AREA IS
UNDER AN AMPLIFYING UPPER LEVEL TROUGH WITH THE RIGHT REAR QUADRANT
OF THE JET. PVA OVER EASTERN IOWA/SOUTHERN MINNESOTA SHOULD HELP TO
INITIATE STORMS. MAXIMUM 700MB OMEGA AND MOISTURE MOVE OVER SOUTHERN
WISCONSIN TONIGHT WITH THE STORMS...WITH A 40-45KT 850MB JET.
INSTABILITY INDICES HIGH WITH CAPES OF 2500-3000 J/KG...LIFTED INDEX
VALUES OF -6 TO -8... AND HELICITY VALUES OF 300-400. THESE FACTORS
GIVE A HIGH CONFIDENCE FOR SEVERE SO WILL LEAVE SEVERE WORDING IN THE
ZONES.

NGM/AVN/RUC ALL FOCUS MOST OF THE PRECIPITATION OVER NORTHERN
MICHIGAN AT THE NOSE OF THE 850MB JET. WHILE THE ETA SPREADS THE
PRECIPITATION ALONG THE FRONT. REGARDLESS PRECIPITATION AMOUNTS ARE
HIGH WITH THIS SYSTEM. MORNING THUNDERSTORMS DUMPED 2 TO 4 INCHES OF
RAIN ACROSS MUCH OF THE CWA...LOWERING FLASH FLOOD GUIDANCE NUMBERS.
THIS FACT...COUPLED WITH THE MODEL PRECIPITATION VALUES...HAS
PROMPTED THE ISSUANCE OF A FLASH FLOOD WATCH.

ALL MODELS PROG FRONTAL PASSAGE TONIGHT WITH THE RAIN ENDING. THE
FRONT WILL BRING COOLER LESS HUMID CONDITIONS TO SOUTHERN WISCONSIN
FOR THE NEXT FEW DAYS. SOUTHERN WISCONSIN SHOULD BEGIN TO CLEAR LATE
TONIGHT.

ONLY CONCERN IN THE LATER PERIODS IS THE FORMATION OF FOG TUESDAY
NIGHT. NGM MOS HAS VERY LOW TEMPERATURES FOR THIS PERIOD...AS WELL AS
CLEAR SKIES. TOO SOON TO WORRY ABOUT FOG NOW BUT WILL MAKE A MENTION
OF IT ON THE ZONES DUE TO THE COPIOUS AMOUNT OF PRECIPITATION
EXPECTED TONIGHT.

.UWNMS...FOCUS PRECIPITATION OVER NORTHERN ILLINOIS...UNLIKE ANY OF
THE OTHER MODELS.

.MKX...FLASH FLOOD WATCH TONIGHT FOR WIZ046-047-051-052-056>060-
062>072.

KURIMSKI

WIZ069>072-112030-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
311 PM CDT MON SEP 11 2000

...SEVERE THUNDERSTORM WATCH 729 HAS BEEN CANCELED FOR EXTREME
SOUTHERN WISCONSIN...

ROCK...WALWORTH...RACINE AND KENOSHA COUNTIES ARE NO LONGER IN
SEVERE THUNDERSTORM WATCH NUMBER 729.

THOUGH THE THREAT OF SEVERE WEATHER HAS PASSED AS OF 300 PM FOR
SOUTHEAST WISCONSIN...WE FULLY EXPECT ANOTHER ROUND OF SEVERE WEATHER
LATER THIS EVENING AND INTO THE NIGHT AS A VIGOROUS SHORTWAVE
AND STRONG JET MOVE ACROSS SOUTHERN WISCONSIN AND INTERACT WITH THE
MOIST UNSTABLE AIR IN PLACE ACROSS THE UPPER MIDWEST.

PLEASE STAY ALERT FOR LATER WATCHES AND WARNINGS.

EISE

WIZ062-067-112200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
434 PM CDT MON SEP 11 2000

...STRONG THUNDERSTORMS HEADED FOR IOWA AND LAFAYETTE COUNTIES...

A LINE OF STRONG THUNDERSTORMS HEADING OUT OF THE NORTHEAST CORNER
OF THE STATE OF IOWA...WILL TRACK ACROSS GRANT COUNTY AND INTO
WESTERN IOWA AND LAFAYETTE COUNTIES BY 500 PM. SOME CITIES TO BE
AFFECTED BY THESE STORMS INCLUDE DODGEVILLE...MINERAL
POINT...BELMONT... DARLINGTON AND SHULLSBURG.

THESE STORMS WERE MOVING NORTHEAST AT 35 MPH. EXPECT WINDS GUSTING
TO NEAR 50 MPH...TORRENTIAL RAINFALL AND POSSIBLY SOME HAIL AS THESE
STORMS PASS THROUGH.

A FLASH FLOOD WATCH IS IN EFFGECT FOR THIS EVENING.

DAVIS

WIZ064>066-069>072-112331-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
513 PM CDT MON SEP 11 2000

...STRONG THUNDERSTORMS OVER SOUTHEAST WISCONSIN...

STRONG THUNDERSTORMS WILL ROLL ACROSS WALWORTH...JEFFERSON...
WAUKESHA...MILWAUKEE...RACINE AND KENOSHA COUNTIES THROUGH 630 PM
CDT. THESE STORMS ARE EXPECTED TO TRACK INTO THE MILWAUKEE
METROPOLITAN AREA BY 6 PM AS THEY MOVE EAST AT 30 MPH.

LOOK FOR GUSTY WINDS OF UP TO 50 MPH...TORRENTIAL RAINFALL REACHING
NEARLY AN INCH PER HOUR AND SMALL HAIL.

STAY INDOORS UNTIL THESE STORMS MOVE THROUGH.

DAVIS