Severe Thunderstorm Warning 89, NWS La Crosse, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
250 AM CDT FRI JUN 23 2000

PRIMARY CONCERNS...THUNDERSTORMS AND SUBSEQUENT FLOODING POTENTIAL
INTO THE WEEKEND.

SURFACE ANALYSIS SHOWED LOW PRESSURE OVER SOUTH DAKOTA WITH FRONTAL
BOUNDARY EXTENDING TO IOWA/NEBRASKA BORDER...THEN EAST-WEST ORIENTED
ALONG MISSOURI/IOWA BORDER INTO CENTRAL IL. DEWPOINTS SOUTH OF THE
FRONT WERE IN THE UPPER 60S TO LOWER 70S. 30 KNOT LOW LEVEL JET
FEEDING CLUSTERS OF THUNDERSTORMS OVER THE PLAINS AS INDICATED IN
PROFILER DATA.

IT SHOULD BE NOTED THERE WERE AWIPS DATA INGEST PROBLEMS...GREATLY
LIMITING THE AMOUNT OF UPPER AIR DATA AVAILABLE TO THE 00Z MODELS.
THE BIGGEST DIFFERENCES NOTED IN THE MODELS WAS PLACEMENT AND AMOUNT
OF QPF. AVN HAD HEAVIEST QPF IN NORTHERN WI...WHILE ETA SHOWED
HEAVIEST QPF FROM THE MN/IOWA BORDER INTO CENTRAL IOWA. IN LIGHT OF
DATA PROBLEMS...WE WILL NOT BE CHANGING THE SPIRIT OF THE FORECAST...
WHICH APPEARS TO BE RIGHT ON TARGET ANYWAY. PREFER TO RETAIN ETA AS
THE MODEL OF CHOICE IN SPITE OF DATA PROBLEMS DUE TO CONSISTENCY ON
OVERALL DETAILS.

LARGE MCS OVER NEBRASKA EXPECTED TO SLIDE SOUTHEAST INTO IOWA AND
MISSOURI THIS MORNING...WHILE CONVECTION IN DAKOTAS MOVES INTO MN.
ETA FORECASTS BOUNDARY TO LIFT NORTHWARD TO THE MN/IOWA BORDER THIS
AFTERNOON/EVENING...WITH LOW LEVEL CONVERGENCE OF THETA-E FOCUSED IN
THAT AREA. UNCERTAINTY STILL EXISTS HOW FAR NORTH THIS BOUNDARY WILL
PUSH...ESPECIALLY WITH ONGOING PLAINS MCS PERHAPS RETARDING NORTHWARD
MOVEMENT.

EXPECT MAIN CONVECTIVE DEVELOPMENT THIS AFTERNOON AND EVENING ACROSS
MN...THEN BUILDING TOWARD THE SOUTHEAST PER CORFIDI VECTORS.
PRECIPITABLE WATER VALUES REACHING 1.75 INCHES WILL BE INTERCEPTING
THE BOUNDARY...WHICH WILL RESULT IN POTENTIAL FOR 1 TO 3 INCHES OF
RAINFALL...WITH ISOLATED HIGHER AMOUNTS. NCEP HAS ENTIRE FORECAST
AREA IN EXCESSIVE RAINFALL OUTLOOK. DUE TO UNCERTAINTY OF WHERE
EXACTLY THE BOUNDARY WILL BE SITUATED AND THE AFOREMENTIONED DATA
PROBLEMS...PREFER TO HOLD OFF ON FLASH FLOOD HEADLINES...BUT WILL ADD
MENTION OF HEAVY RAIN POTENTIAL IN ZONES FOR TONIGHT.

FRONTAL BOUNDARY REMAINS ACROSS THE UPPER MISSISSIPPI VALLEY THROUGH
THE WEEKEND...SO CONTINUED LIKELIHOOD OF THUNDERSTORMS AS IN CURRENT
FORECAST.

THANKS TO MPX...DMX AND MKX FOR COORDINATION THIS MORNING.

.LSE...NONE.

THOMPSON

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-231800-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
600 AM CDT FRI JUN 23 2000

...A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY AND TONIGHT ACROSS
SOUTHEAST MINNESOTA...NORTHEAST IOWA AND SOUTHWEST INTO CENTRAL
WISCONSIN...

A LOW PRESSURE CENTER WAS LOCATED NEAR HURON SOUTH DAKOTA EARLY THIS
MORNING. A WARM FRONT EXTENDED SOUTHEAST OF THIS LOW...ACROSS EXTREME
WESTERN IOWA...AND THEN EAST INTO NORTHEAST MISSOURI AND CENTRAL
ILLINOIS. WARM MOIST AIR WILL SURGE NORTHWARD TODAY...AS THE WARM
FRONT LIFTS THROUGH IOWA AND NORTHERN ILLINOIS. THE ATMOSPHERE WILL
DESTABILIZE OVER THE AREA AS THE FRONT PUSHES NORTH TODAY...CREATING
A FAVORABLE ENVIRONMENT FOR THUNDERSTORM DEVELOPMENT...WITH SOME
POSSIBLY BECOMING SEVERE.

THE WARM FRONT WILL SERVE AS THE FOCUS FOR THUNDERSTORM DEVELOPMENT
THIS AFTERNOON ACROSS NORTHERN IOWA. THE STORMS WILL THEN PROPAGATE
EAST OR SOUTHEAST ALONG THE FRONT. THE MAIN SEVERE THREAT FROM THESE
STORMS WILL BE WIND GUSTS IN EXCESS OF 58 MPH.

ONCE THE STORMS DEVELOP...THE WARM FRONT WILL BECOME NEARLY
STATIONARY. STORMS WILL THEN CONTINUE TO DEVELOP AND MOVE ALONG THIS
FRONT INTO THE EVENING HOURS...CREATING THE POTENTIAL FOR LOCALIZED
HEAVY RAIN FROM NORTHEAST IOWA INTO SOUTHWEST WISCONSIN. SATURATED
SOILS WILL CAUSE ANY RAIN THAT DOES FALL TO RUN OFF...WHICH WILL
INCREASE THE THREAT OF FLOODING IN THESE AREAS.

SPOTTER GROUPS SHOULD MONITOR LATER STATEMENTS...AS SPOTTER
ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

CONSIDINE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
1004 AM CDT FRI JUN 23 2000

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ...COUNTY LOCATION....
6
1000 AM    3 E CHARLES CITY               1.00 INCH HAIL
06/23/00   FLOYD                          REPORTED BY CO-OP OBSERVER

KRC