Severe Thunderstorm Warning 31, NWS La Crosse, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
317 PM CDT SAT JUN 28 2003

FORECAST CONCERNS ARE PRECIPITATION CHANCES TONIGHT...THEN
TEMPERATURES THROUGH THE MIDDLE OF NEXT WEEK.

18Z SURFACE ANALYSIS SHOWS A WEAK AREA OF LOW PRESSURE BETWEEN KONA
AND KMSP. WEAK BOUNDARY EXTENDS ALONG MISSISSIPPI RIVER
NORTHWESTWARD INTO NORTHERN MINNESOTA....WITH WARM FRONT EXTENDING
SOUTHEASTWRD INTO NORTHERN ILLINOIS. SCATTERED CONVECTION DEVELOPED
OVER THE PAST HOUR ACROSS WESTERN WISCONSIN IN VICINITY OF BOUNDARY.
WITH MAIN THREAT TO BE LARGE HAIL. FARTHER NORTHWEST...WATER VAPOR
IMAGERY SHOWING SHORTWAVE ACROSS NORTHWESTERN MINNESOTA MOVING
SOUTHEASTWARD. WITH CONVECTION DEVELOPING OUT AHEAD OF THIS FEATURE.

ONLY MINOR INITIALIZATION ERRORS SEEN IN 12Z/JUN 28TH MODELS.
MODELS ARE ALSO IN GOOD AGREEMENT...ALTHOUGH GFS MORE ROBUST WITH
CONVECTION DEVELOPING ACROSS THE CENTRAL PLAINS FROM SUNDAY NIGHT
INTO MONDAY AND PREFER THE ETAS FARTHER SOUTHWARD PROGRESSION OF
SYSTEM.

IN THE SHORT TERM...CONVECTION NOW OCCURRING ACROSS WESTERN
WISCONSIN AHEAD OF AFOREMENTIONED BOUNDARY. LAPS SHOWING CAPES
OF 1000 TO 2000 J/KG WITH CAPES OF 1000 TO 2000 J/KG...MAINLY EAST OF
THE MISSISSIPPI RIVER. WILL COVER WITH SCATTERED POPS THIS EVENING.
NEXT WAVE NOW IN NORTHWEST MINNESOTA DROPS SOUTHEASTWARD THIS
EVENING. BEST FORCING TO REMAIN ACROSS THE NORTHERN AND EASTERN
ZONES. IN ADDITION...JET MAX SLIDING DOWN BACKSIDE OF TROUGH TO
ENHANCE LIFT. INSTABILITIES AT THIS TIME SOMEWHAT MARGINAL....UT
EXPECT CONVECTION NOW IN CENTRAL MINNESOTA TO CONTINUE TO TRANSLATE
SOUTHEASTWARD TOWARD AREA. WAVE EXITS AREA LATER TONIGHT WITH
SUBSIDENCE IN ITS WAKE.

HIGH PRESSURE THEN BUILDS IN TO THE AREA THE REMAINDER OF THE
WEEKEND AND INTO EARLY NEXT WEEK...AS FRONT GETS SHOVED TO THE
SOUTH. LATEST GFS POINTS TOWARD PRECIPITATION CHANCES HOLDING OFF
UNTIL WEDNESDAY NIGHT OR THURSDAY...THUS HAVE REMOVED POPS FOR
TUESDAY...AS HIGH REMAINS ACROSS THE EASTERN GREAT LAKES.

GUIDANCE NUMBERS LOOK REASONABLE...SO ONLY MINOR DEVIATIONS FROM
THEM. ALL IN ALL ONLY MADE MINOR TWEAKS TO THE TEMPERATURES FROM
PREVIOUS FORECAST.

IN THE 4 TO 7 DAY TIME FRAME...UPPER FLOW TO TRANSITION TO A MORE
ZONAL PATTERN...WITH MAIN WESTERLIES ACROSS ACROSS THE NORTHERN
TIER OF STATES. HIGH HOLDS ON THROUGH WEDNESDAY AS SYSTEM GETS
ORGANIZED ACROSS THE PLAINS. ASSOCIATED FRONT LOOKS TO MOVE TOWARD
THE AREA ON THURSDAY AND FRIDAY BEFORE STALLING OUT SOMETIME ON
SATURDAY. WILL KEEP POPS GOING THURSDAY THROUGH SATURDAY.

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

RABERDING

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-291100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
115 PM CDT SAT JUN 28 2003

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

THE STORM PREDICTION CENTER INDICATES THERE IS A SLIGHT RISK OF
SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT MAIN EAST OF A
ROCHESTER MINNESOTA TO WAUKON IOWA LINE.

THIS AFTERNOON...INCREASED SUNSHINE HAS HELPED TO DESTABILIZE THE
ATMOSPHERE ACROSS THE AREA. A COLD FRONT...EXTENDING FROM A LOW OVER
NORTHWEST WISCONSIN...WILL SERVE AS A TRIGGER FOR SCATTERED SHOWERS
AND STORMS IN THIS DESTABILIZING AIR. THIS FRONT WILL MOVE SLOWLY
ACROSS WESTERN WISCONSIN THIS AFTERNOON...PUTTING THE BEST CHANCES
FOR STORMS IN THAT AREA. WIND PROFILES AND THE INSTABILITY SUPPORT
STORM DEVELOPMENT...WITH STRONG WIND GUSTS AND HAIL POSSIBLE.

TONIGHT...AN UPPER LEVEL DISTURBANCE WILL ROTATE SOUTH ACROSS THE
AREA...WHILE A WEAK FRONTAL BOUNDARY WAVERS FROM NORTHERN MINNESOTA
THROUGH SOUTHEAST WISCONSIN. MOISTURE AND INSTABILITY ARE EXPECTED
TO BE SOMEWHAT LIMITED. HOWEVER...STRONG WIND SHEAR ALOFT WILL
SPREAD OVER THE AREA AS THE DISTURBANCE MOVES ACROSS THE REGION. THE
COMBINATION OF THE FRONTAL BOUNDARY IN THE AREA AND THE STRONG WIND
SHEAR WILL BE FAVORABLE FOR THUNDERSTORM DEVELOPMENT THIS EVENING. A
FEW OF THE STORMS MAY BECOME SEVERE...WITH MAIN THREATS BEING LARGE
HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NEEDED LATE THIS AFTERNOON AND
TONIGHT.

RIECK/RRS