Severe Thunderstorm Warning 20, NWS La Crosse, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
315 AM CDT WED MAY 17 2000

THE 00Z ETA/AVN MODEL RUNS COMPARABLE...KEEPING THE WARM FRONT SOUTH
OF MOST OF THE FORECAST AREA...AS FIRST THOUGHT ON MONDAY. AVN ALSO
A BIT FASTER WITH THE 500 MB TROUGH COMPARED TO THE ETA. EITHER
MODEL/S QPF NOT DOING WELL WITH CURRENT PCPN TRENDS. WILL USE AN
ETA/AVN BLEND FOR THE FORECAST.

MCS PLACEMENT EARLY THIS MORNING NOT WHERE INITIALLY
EXPECTED...WHICH WILL IMPACT THE FORECAST FOR TODAY AND THURSDAY.
THUNDERSTORM/SHOWER COMPLEXES CURRENTLY OVER THE NORTHERN PLAINS AND
MO. THE MCS/S WILL KEEP THE WARM FRONTAL BOUNDARY FARTHER
SOUTH...WHICH SHOULD HOVER FROM CENTRAL IA THROUGH NORTHERN ILL
THROUGH 00Z FRIDAY. THE 500 MB CLOSED LOW WILL WEAKEN AND OPEN BY
THURS AFTERNOON...WITH THE MAIN AXIS FROM WESTERN IA INTO WESTERN KS
BY THURS NIGHT. MODELS SPIT OUT A VORT MAX ACROSS THE RIDGE AND
THROUGH SOUTHERN WI AND NORTHERN WI THIS AFTERNOON. THIS APPEARS TO
BE YET ANOTHER CONVECTIVE INDUCED VORT MAX FROM THIS MORNING/S
THUNDERSTORM ACTIVITY OVER THE PLAINS. BEST ENERGY WITH THE TROUGH
WILL BE OVERNIGHT INTO THURSDAY MORNING. GOOD WARM AIR/MOISTURE
ADVECTION ACROSS THE WARM FRONT TONIGHT...ALONG WITH ISENTROPIC LIFT
ALONG THE 300 K SURFACE...WILL SUPPLY ENOUGH DYNAMICS FOR SHOWERS
AND THUNDERSTORMS ACROSS THE REGION. LESS FAVORABLE ACROSS THE
NORTHERN CUTS. BEST CAPES AND LI/S WILL BE SOUTH OF THE WARM
FRONT...BUT ELEVATED CONVECTION POSSIBLE JUST NORTH OF IT. SPC HAS
PORTIONS OF NE IA IN A SLIGHT RISK AND THAT LOOKS REASONABLE...WITH
MAIN THREAT BEING LARGE HAIL. SO IT LOOKS LIKE BEST PCPN CHANCES FOR
THE FORECAST AREA WILL START LATE THIS AFTERNOON AND CONTINUE INTO
THURSDAY. MOST SIGNIFICANT RAINFALL FOR THE FORECAST AREA LOOKS TO
ALSO SET UP ACROSS NORTHEAST IA.

FOR TEMPERATURES...WITH THE WARM FRONT STAYING MOSTLY SOUTH OF THE
FORECAST AREA...IT WILL BE COOL TO SEASONABLE. 850 MB TEMPS AND
1000:500 MB THICKNESS DON/T VARY MUCH OVER THE NEXT COUPLE DAYS.
CLOUDS AND RAIN SHOULD ALSO SERVE TO HOLD READINGS DOWN. EAST WINDS
WON/T ALLOW FOR MUCH OF WARM UP EITHER. LIKE FAN GUIDANCE OVER FWC.

.LSE...NONE.

RIECK

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-171800-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
415 AM CDT WED MAY 17 2000

...LARGE HAIL POSSIBLE IN NORTHEAST IOWA AND EXTREME SOUTHWEST
WISCONSIN THIS EVENING AND OVERNIGHT...

A WARM FRONT WILL PUSH NORTH INTO IOWA THIS AFTERNOON AND SETTLE
ACROSS CENTRAL IOWA THIS EVENING. THUNDERSTORMS WILL DEVELOP ALONG
AND AHEAD OF THE WARM FRONT AND PUSH NORTH INTO OUR AREA LATER THIS
AFTERNOON.  THE ATMOSPHERE WILL BE MODERATELY UNSTABLE ABOVE THE
WARM FRONT...AND SOME STRONG TO SEVERE THUNDERSTORMS MAY DEVELOP
LATER TODAY.  FURTHER TO THE NORTH IN SOUTHEAST MINNESOTA AND WEST
CENTRAL WISCONSIN...THERE WILL BE THE CHANCE OF THUNDERSTORMS...BUT
THEY ARE NOT EXPECTED TO BECOME SEVERE.

THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS IN NORTHEAST IOWA
AND EXTREME SOUTHWEST WISCONSIN LATER TODAY AND TONIGHT. THE WARM
FRONTS POSITION WILL KEEP RELATIVELY STABLE AIR CLOSE TO THE
SURFACE...WHICH SHOULD PREVENT STRONG WINDS FROM MAKING IT TO THE
SURFACE. THEREFORE THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE
LARGE HAIL.

SPOTTER ACTIVATION MAY BE NECESSARY IN NORTHEAST IOWA AND EXTREME
SOUTHWEST WISCONSIN TOWARDS EVENING AND OVERNIGHT.  STAYED TUNED FOR
LATER STATEMENTS.

NELSON

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-171800-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
415 AM CDT WED MAY 17 2000

...LARGE HAIL POSSIBLE IN NORTHEAST IOWA AND EXTREME SOUTHWEST
WISCONSIN THIS EVENING AND OVERNIGHT...

A WARM FRONT WILL PUSH NORTH INTO IOWA THIS AFTERNOON AND SETTLE
ACROSS CENTRAL IOWA THIS EVENING. THUNDERSTORMS WILL DEVELOP ALONG
AND AHEAD OF THE WARM FRONT AND PUSH NORTH INTO OUR AREA LATER THIS
AFTERNOON.  THE ATMOSPHERE WILL BE MODERATELY UNSTABLE ABOVE THE
WARM FRONT...AND SOME STRONG TO SEVERE THUNDERSTORMS MAY DEVELOP
LATER TODAY.  FURTHER TO THE NORTH IN SOUTHEAST MINNESOTA AND WEST
CENTRAL WISCONSIN...THERE WILL BE THE CHANCE OF THUNDERSTORMS...BUT
THEY ARE NOT EXPECTED TO BECOME SEVERE.

THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS IN NORTHEAST IOWA
AND EXTREME SOUTHWEST WISCONSIN LATER TODAY AND TONIGHT. THE WARM
FRONTS POSITION WILL KEEP RELATIVELY STABLE AIR CLOSE TO THE
SURFACE...WHICH SHOULD PREVENT STRONG WINDS FROM MAKING IT TO THE
SURFACE. THEREFORE THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE
LARGE HAIL.

SPOTTER ACTIVATION MAY B`E NECESSARY IN NORTHEAST IOWA AND EXTREME
SOUTHWEST WISCONSIN TOWARDS EVENING AND OVERNIGHT.  STAYED TUNED FOR
LATER STATEMENTS.

NELSON