Severe Thunderstorm Warning 1, NWS La Crosse, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
230 PM CDT WED APR 30 2003

MAIN FORECAST CONCERNS CENTER ON THE PCPN CHANCES FOR TONIGHT INTO
THU...AND THEN THE TEMPERATURES.

12Z ETA/GFS MODEL SOLUTIONS ARE REASONABLY SIMILAR WITH THE MAIN
WEATHER FEATURES FOR THE NEXT FEW DAYS...WITH NOTHING GLARING FOR
THE REGION. LONG TERM MODELS A DIFFERENT STORY...WITH THE MRF AND
ECMWF SHOWING SIGNIFICANT DIFFERENCES OUT TOWARD THE BEGINNING OF
NEXT WEEK. WITHOUT A GOOD FEEL EITHERWAY...WILL LEAN TOWARD THE
ENSEMBLES FOR NOW.

THE 18Z SURFACE ANALYSIS PLACED A LOW OVER CENTRAL NEB...WITH A WARM
FRONT RUNNING NORTHEAST INTO CENTRAL ILL AND IND. NORTH OF THE
FRONT...88-D RADAR IMAGERY CONTINUED TO INDICATE AREAS OF SHOWERS
AND THUNDERSTORMS...WITH THE MOST ACTIVE AREA BEING OVER EASTERN
IOWA AND NORTHERN ILL.

SLOW MOVING 500 MB SHORTWAVE TROUGHS EJECTING OUT OF THE ROCKIES
INTO THE REGION OVER THE NEXT COUPLE DAYS...STAYING MOSTLY
SOUTH...OVER IOWA AND ILL. A SURFACE HIGH OVER SOUTHERN CANADA SAGS
OVER THE NORTHERN GREAT LAKES DURING THIS TIME...HELPING TO KEEP
THESE UPPER LEVEL FEATURES MAINLY SOUTH...ALONG WITH HELPING TO
CONTINUE TO NUDGE THE FRONTAL BOUNDARY EAST AND SOUTHEAST. SOME
UPPER LEVEL QG /700:300 MB/ CONVERGENCE INDICATED THROUGH 00Z FRI.
HOWEVER...THE LOW LEVEL JET AND MOISTURE TRANSPORT VECTORS HOLD IN
THE VICINITY OF THE FRONT...BRINGING THEIR INFLUENCE TO BEAR ACROSS
ILL...IND AND MICH TONIGHT INTO THU. GOOD 850 MB WARM AIR ADVECTION
FOR THE EVENING HOURS TONIGHT THOUGH....CENTERED FROM NORTHEAST IOWA
THROUGH SOUTHERN WI. THIS WILL SHIFT TO THE SOUTHEAST OVERNIGHT.
SHOWERS SHOULD LINGER THROUGH THE EVENING HOURS...MAINLY TO THE EAST
AND SOUTHEAST. 300 MB JET MAX WILL PUSH INTO THE AREA FROM THE
SOUTHERN PLAINS...AND 0-3KM IS GOOD OVER THE FORECAST AREA THIS
EVENING. THE BETTER INSTABILITY TO THE SOUTH THOUGH. SO...THINK
THERE COULD STILL BE SOME THUNDER CHANCES...BUT MORE LIKELY OFF TO
THE EAST AND SOUTHEAST. WILL CONTINUE OCCASIONAL OR SCATTERED
MENTION FOR THE FORECAST AREA.

ON THU...THE SURFACE HIGH WILL START TO SINK TO THE SOUTH...PUSHING
THE FRONTAL BOUNDARY IN THE SAME DIRECTION. RH FIELDS AND FORECAST
SOUNDINGS INDICATE GOOD SATURATION THROUGH MOST OF THE DAYTIME
HOURS...ALTHOUGH SOME CLEARING FROM NORTH TO SOUTH WILL BE LIKELY.
HOWEVER...WITH A-GEOSTOPHIC IMPLIED MOTIONS FROM THE UPPER LEVEL
JET...ALONG WITH THE AFOREMENTIONED QG CONVERGENCE AND THE VICINITY
OF THE SURFACE FRONT...THINK SMALL SHOWER CHANCES ARE WARRANTED FOR
THE SOUTHERN TIER OF THE FORECAST AREA.

THE HIGH SHOULD BE THE MAIN INFLUENCE FOR THE UPPER MISSISSIPPI
RIVER VALLEY ON FRIDAY...ALTHOUGH RH FIELDS AND SOUNDINGS CONTINUE
TO INDICATED SOME LINGERING MID LEVEL SATURATION. SO...MOSTLY SUNNY
TO THE NORTH...AND PARTLY SUNNY TO THE SOUTH LOOKS REASONABLE RIGHT
NOW.

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

RIECK

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034-
041>044-053>055-061-011100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
1243 PM CDT WED APR 30 2003

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING GENERALLY SOUTH OF AN OELWEIN IOWA...TO BOSCOBEL WISCONSIN
LINE. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE PLAINS INTO
THE LOWER GREAT LAKES REGION BY THIS EVENING. MEANWHILE...AT THE
SURFACE...A WARM FRONT...CURRENTLY LOCATED OVER SOUTHERN IOWA...
WILL LIFT NORTHWARD INTO CENTRAL IOWA AND NORTHERN ILLINOIS. SHOWERS
AND THUNDERSTORMS WILL LIKELY INTENSIFY IN THE VICINITY OF THE
BOUNDARY THIS AFTERNOON ACROSS IOWA AND THEN SPREAD EAST NORTHEAST
TOWARD NORTHEAST IOWA AND SOUTHWEST WISCONSIN. ENOUGH ELEVATED
INSTABILITY WILL EXIST TO THE NORTH OF THE FRONT TO PRODUCE SOME
LARGE HAIL ACROSS THE SLIGHT RISK AREA AFTER 230 PM THIS AFTERNOON AND
EVENING. IN ADDITION...SOME LOCALLY HEAVY RAINFALL IS POSSIBLE
THROUGH THIS EVENING...WITH RAINFALL AMOUNTS OF AN INCH TO AND INCH
AND ONE HALF POSSIBLE ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

QUIET WEATHER IS EXPECTED THROUGH SATURDAY. ON SUNDAY...A STORM
SYSTEM IS EXPECTED TO MOVE OUT OF THE CENTRAL PLAINS TOWARD THE
GREAT LAKES REGION....BRINGING ANOTHER CHANCE OF SHOWERS AND
THUNDERSTORMS FROM SUNDAY THROUGH TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER THIS AFTERNOON AND EVENING
ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN.

BOYNE