Severe Thunderstorm Warning 18, NWS La Crosse, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
155 PM CDT WED MAY 14 2003

FORECAST CONCERNS CENTER AROUND UPPER LOW AND RESIDUAL PRECIPITATION
TONIGHT.

14/18Z SURFACE MAP HAS STACKED 1007MB SURFACE LOW OVER SOUTHWEST
CORNER OF MN MOVING SOUTHEAST. RADAR AND SATELLITE SHOWING BAND OF
THUNDERSTORMS DEVELOPING ON EAST EDGE SURFACE VORTICITY AXIS.
REPORTS OF SOME HAIL AND BRIEF SPIN-UPS ASSOCIATED WITH THESE STORMS.

14/12Z ETA/GFS RUNS INITIALIZED FAIRY WELL WITH NO MAJOR DIFFERENCES
NOTED ALOFT OR AT THE SURFACE.

FOR TONIGHT...UPPER LOW AND ASSOCIATED COLD POOL SHRA/TS ACTIVITY
WILL CONTINUE TO PINWHEEL SOUTHEAST TONIGHT BEFORE OPENING UP INTO A
BROAD CYCLONIC CIRCULATION OVERHEAD BY THURSDAY MORNING. SHOWERS
AND T-STORMS WILL END FROM NORTH TO SOUTH ACROSS THE AREA WITH
SOUTHEAST TREK OF UPPER LOW. LOOKS LIKE FAR SOUTHWEST WI AND NE IA
MAY SEE SOME SHOWERS LINGERING TIL MORNING. ETA RH FIELDS DO SHOW A
GRADUAL DECREASE IN CLOUDS MAINLY ACROSS CLARK AND TAYLOR COUNTIES
WITH THE REST OF THE AREA REMAINING MOSTLY CLOUDY.

BROAD CYCLONIC FLOW AND ASSOCIATED COLD POOL LINGERS OVERHEAD
THURSDAY WITH H8-H5 LAPSE RATES REACHING 6-7C/KM BY AFTERNOON.
RATHER WEAK CAPE OF 100-200 J/KG OVER MUCH OF THE AREA ALONG WITH A
WEAK LOBE OF H5-H3 PVA ROTATING SOUTHEAST ACROSS THE AREA. WILL
MENTION A SLIGHT CHANCE OF SHRA ACROSS THE ENTIRE AREA BASED ON
THIS.

SKIES GO PARTLY CLOUDY THURSDAY NIGHT AS UPPER AND SURFACE RIDGE
BUILDS ACROSS AREA. DROPPED LOWS A COUPLE DEGREES BASED ON CLEARING
SKIES AND LIGHT WINDS.

UPPER RIDGE CONTINUES TO BUILD OVER AREA ON FRIDAY. SOME INCREASE IN
MID/HIGH CLOUDS OVER THE WESTERN FORECAST AREA TROUGH FRIDAY NIGHT IN
RETURN FLOW ON BACKSIDE OF SURFACE HIGH.

ON SATURDAY...COLD FRONT FROM LOW OVER MANITOBA BRUSHES NORTHERN CWA
DURING THE AFTERNOON HOURS. ETA SHOWING ENOUGH H8 MOISTURE
TRANSPORT AND ISENTROPIC UPGLIDE TO WARRANT AT LEAST A SMALL CHANCE
OF SHRA/TS ACROSS NORTHERN TIER OF THE FORECAST AREA.

FOR SUNDAY THROUGH WEDNESDAY: SPLIT FLOW REGIME TRANSITIONS TO PHASED
FLOW BY MONDAY. ECMWF AND GFS BOTH SHOWING STACKED LOW PASSING WELL
SOUTH OF OUR AREA SUNDAY THROUGH EARLY MONDAY. UPPER RIDGE HOLDS
OVER OUR AREA THROUGH MONDAY BEFORE NEXT CANADIAN/NORTHERN PLAINS
SYSTEM AFFECTS THE AREA BY TUESDAY. BELIEVE SLOWER GFS A LITTLE MORE
REASONABLE THAN ECMWF IN SPEED OF SYSTEM GIVEN STRENGTH/AMPLITUDE OF
HIGH PRESSURE RIDGE. FLAT UPPER ZONAL FLOW WITH SURFACE RIDGE BUILDS
IN ON WEDNESDAY FOR TRANQUIL CONDITIONS.

.LSE...WATCHES/WARNINGS/ADVISORIES...NONE.

DAS

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-151100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
110 PM CDT WED MAY 14 2003

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

.DAY ONE...TODAY AND TONIGHT

A WEAK FRONTAL BOUNDARY EXTENDS FROM A LOW ACROSS SOUTHWEST
MINNESOTA...TO ANOTHER LOW IN EASTERN IOWA. THUNDERSTORMS HAVE
DEVELOPED ALONG THIS BOUNDARY ACROSS SOUTHERN MINNESOTA AND INTO FAR
NORTH CENTRAL IOWA. A FEW OF THE STORMS MAY BECOME SEVERE WITH LARGE
HAIL. STORMS NEAR THE BOUNDARY MAY ALSO SPIN UP A WEAK SHORT LIVED
TORNADO. THE MAIN THREAT FOR THE SEVERE WEATHER WILL BE TO THE WEST
OF A GUTTENBERG IOWA...TO ROCHESTER MINNESOTA LINE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

LIMITED SPOTTER ACTIVATION MAY BE NEEDED THROUGH EARLY EVENING
ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA.

RABERDING

IAZ008>010-018-019-029-030-MNZ079-086>088-094>096-WIZ054-061-142200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
128 PM CDT WED MAY 14 2003

...FUNNELS AND BRIEF TORNADOES POSSIBLE THIS AFTERNOON...

THUNDERSTORMS WERE DEVELOPING OVER SOUTH CENTRAL MINNESOTA EARLY
THIS AFTERNOON. THESE THUNDERSTORMS WERE LOCATED ALONG A FRONT OR
WIND SHIFT LINE EXTENDING FROM MANKATO MINNESOTA TO APPROXIMATELY
MASON CITY IOWA. SOME REPORTS HAVE BEEN RECEIVED OF FUNNELS AND
BRIEF TORNADOES WITH THE STORMS LOCATED ON THE FRONT....BUT MAINLY
HAIL UP TO ONE INCH IN DIAMETER AND BRIEF HEAVY RAIN.

OVER THE NEXT SEVERAL HOURS...THE FRONT WILL MOVE VERY SLOWLY EAST
AND STALL IN SOUTHEAST MINNESOTA AND NORTHEAST IOWA. THE FRONT WILL
BE LOCATED ALONG A LINE FROM ALBERT LEA TO WATERLOO IOWA BY 6 PM.
THIS FRONT HAS A SHARP WIND SHIFT FROM EAST TO WEST AND FAVORS
WEAKER AND SHORT-LIVED TORNADOES.

THEREFORE...THOSE IN DODGE...MOWER...MITCHELL...FLOYD...AND
CHICKASAW COUNTIES MAY SEE THIS ACTIVITY MOVE IN FROM THE WEST
THROUGH THE AFTERNOON. THIS INCLUDES THE TOWNS OF DODGE
CENTER...AUSTIN...OSAGE...CHARLES CITY...AND NEW HAMPTON.

THESE TORNADOES ARE NOT TYPICALLY MAJOR AND LONG-LIVED...LASTING
ONLY A FEW MINUTES. THEY TYPICALLY DO VERY LITTLE DAMAGE.
HOWEVER...STAY ABREAST OF CHANGING WEATHER CONDITIONS AND YOUR
FAVORITE MEDIA SOURCE FOR FURTHER UPDATES.

BAUMGARDT