Flash Flooding and Flood in Minnesota, June 18 to 19, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
316 AM CDT SAT JUN 18 2011

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

RATHER DIFFICULT FORECAST SCENARIO OVER THE NEXT SEVERAL DAYS...WITH
RAIN CHANCES BEING THE MAIN WEATHER CONCERN.

06Z SURFACE ANALYSIS SHOWS A FRONTAL BOUNDARY EXTENDING ACROSS
WESTERN MINNESOTA...WITH A WEAK LOW NEAR KULM. CONVECTION HAS BEEN
OCCURRING OUT OF AHEAD OF THIS FROM CENTRAL MINNESOTA...INTO
NORTHWEST AND CENTRAL WISCONSIN.

18.00Z MODELS AGREE WITH THEIR MASS FIELDS...BUT CONTINUE TO
STRUGGLE WITH THE DETAILS FOR CONVECTION AND THUS OVERALL CONFIDENCE
NOT HIGH WITH THIS FORECAST. SOUTHWEST FLOW WILL CONTINUE INTO
MONDAY WITH SUBTLE MID LEVEL DISTURBANCES TRACKING THROUGH THE FLOW.

IN THE NEAR TERM...WEAK SHORTWAVE AS SEEN ON WATER VAPOR IMAGERY
PUSHING THOUGH NORTHERN IOWA/SOUTHERN MINNESOTA HELPING TO MAINTAIN
CONVECTION OVER MINNESOTA AND WISCONSIN AND THIS SHOULD PUSH EAST
OF THE AREA LATER THIS MORNING. MODELS ALSO SHOWING ANOTHER WEAK
WAVE POSSIBLE THIS AFTERNOON AND THUS HAVE MAINTAINED CHANCE
PROBABILITIES WITH THE HIGHEST ACROSS THE NORTHEAST. ALTHOUGH
MODELS INDICATING 2000 J/KG TO 3000 J/KG OF MOST UNSTABLE CAPES THIS
AFTERNOON...SHEAR VALUES ARE ONLY 20 TO 30 KNOTS. THUS EXPECT
SEVERE THREAT TO REMAIN SOUTH AND WEST OF THE AREA IN MORE FAVORED
AREA.

BOTH THE NAM AND GFS HINTING AT POTENTIAL MCS DEVELOPMENT TONIGHT...
ALBEIT THEY DIFFER IN BOTH STRENGTH AND LOCATION. MOISTURE
TRANSPORT NOT ALL THAT IMPRESSIVE...WITH THE NAM FOCUS WELL TO THE
SOUTH OF THE AREA...WHILE GFS HAS TONGUE FURTHER NORTH INTO THE
AREA. HOWEVER GFS QPF FIELDS LOOK TO BE SUFFERING FROM CONVECTIVE
FEEDBACK PROBLEMS. LOOKS AS THOUGH BEST POTENTIAL WILL BE ACROSS
THE WESTERN HALF AND WILL HAVE HIGHEST PROBABILITIES IN THIS AREA.
ONCE AGAIN SHEAR LOOKS TO BE QUITE LIMITED AND NOT EXPECTING ANY
ORGANIZED SEVERE WEATHER. THIS COMPLEX WILL THEN SHIFT NORTHEAST
SUNDAY AND HAVE TAPERED PROBABILITIES FROM WEST TO EAST..WITH THE
BETTER CHANCES ACROSS THE NORTHEAST SECTIONS.

ATTENTION THEN TURNS TO TO SHARPENING TROUGH ACROSS THE WEST AS 120
KNOT JET DIGS ALONG THE PACIFIC NORTHWEST CARVING OUT A 500MB CLOSED
LOW OVER THE PLAINS ON MONDAY. ATTENDANT SURFACE LOW THEN
LIFTS INTO WESTERN MINNESOTA WITH A STRENGTHENING WARM FRONT
EXTENDING EASTWARD. THIS FRONT WILL LIKELY PUSH INTO/NEAR THE
FORECAST AREA AND BECOME THE FOCUS FOR CONVECTION AS MOISTURE
TRANSPORT INCREASES. THIS ALSO LOOKS TO BE THE BEST CHANCE FOR
SEVERE WEATHER AS AMPLE CAPE AND 0-6KM SHEAR VALUES IN THE 40 TO
45 KNOT RANGE WILL EXIST. STILL UNCERTAINTIES AS TO HOW THIS WILL
ALL EVOLVE...BUT CERTAINLY WORTH KEEPING AN EYE ON. MODELS HAVE BEEN
RATHER CONSISTENT WITH THIS EVOLUTION AND THUS HAVE GONE WITH 50 TO
60 PERCENT CHANCES FOR MONDAY AND MONDAY NIGHT.

.LONG TERM...TUESDAY THROUGH FRIDAY

UNSETTLED WEATHER WILL CONTINUE TUESDAY THROUGH THURSDAY AS
AFOREMENTIONED UPPER LEVEL SYSTEM TRACKS ACROSS THE FORECAST AREA.
DEPENDING UPON SPEED...STILL COULD BE A SEVERE THREAT ON
TUESDAY WITH SYSTEM STILL JUST WEST OF THE AREA. MODEL
CONSENSUS GIVING HIGH PROBABILITIES FOR TUESDAY AND TUESDAY NIGHT
WHICH SEEMS QUITE REASONABLE GIVEN PROXIMITY OF SURFACE AND UPPER
LOW. RAIN CHANCES WILL CONTINUE INTO THURSDAY BEFORE IT PULLS EAST OF
THE AREA ON FRIDAY.

TEMPERATURES LOOK TO BE BELOW NORMAL THROUGH THE PERIOD WITH HIGHS
MAINLY IN THE 70S.

&&

.AVIATION...

CONSIDERABLE UNCERTAINTY IN THE FCST DURING THE NEXT 24-48 HRS.
A MOIST AND UNSTABLE AIRMASS WILL BE OVER THE AREA/REGION TODAY THRU
SUN. HOWEVER FORCING MECHANISMS FOR CONVERGENCE/LIFT TO INITIATE
CONVECTION ON THE WEAK SIDE...WITH PLENTY OF TIMING/LOCATION
DIFFERENCES SEEN AMONG THE FCST MODELS THIS CYCLE. THIS LEADS TO A
RATHER LOW CONFIDENCE FCST...EVEN IN THE NEAR TERM OF TODAY/TONIGHT.

ONE WEAK SHORTWAVE AND BAND OF -SHRA/SCT TSRA WILL LIFT NORTH-EAST
OF THE TAF SITES EARLY THIS MORNING. GENERAL VFR CONDITIONS EXPECTED
THRU THE MORNING...BUT FOR SOME PATCHY MVFR VSBYS IN BR AROUND
SUNRISE DUE TO THE MOIST BOUNDARY LAYER. LOOSE MODEL CONSENSUS FOR
ANOTHER COUPLE OF WEAK SHORTWAVES TO BE APPROACHING THE AREA THIS
AFTERNOON THEN MOVING OVER THE AREA TONIGHT ALONG WITH A WEAK SFC
TROUGH. PLENTY OF MODEL DETAIL DIFFERENCES OF TIMING/STRENGTH OF
THESE FEATURES...AND RESULTING CONVECTION. OWING TO THE
UNCERTAINTY...WILL BE CONSERVATIVE WITH TSRA MENTIONS IN TAFS AND
LIMIT MENTION TO CB FOR NOW UNTIL A CLEARER TIMING SIGNAL CAN BE
SEEN. IF OR WHEN TSRA DO OCCUR...MVFR CIGS/IFR VSBYS CAN BE EXPECTED
WITH THEM...WITH MVFR VSBYS IN SHRA. FOR NOW APPEARS THE GREATEST
THREAT/COVERAGE OF SHRA/TSRA WOULD BE LATE TONIGHT INTO SUN MORNING
WITH PASSAGE OF THE SHORTWAVES AND A MID LEVEL TROUGH.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

SHORT/LONG TERM...RABERDING
AVIATION..........RRS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI
500 AM CDT SAT JUN 18 2011

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-191100-
ADAMS-ALLAMAKEE-BUFFALO-CHICKASAW-CLARK-CLAYTON-CRAWFORD-DODGE-
FAYETTE-FILLMORE-FLOYD-GRANT-HOUSTON-HOWARD-JACKSON-JUNEAU-
LA CROSSE-MITCHELL-MONROE-MOWER-OLMSTED-RICHLAND-TAYLOR-TREMPEALEAU-
VERNON-WABASHA-WINNESHIEK-WINONA-
500 AM CDT SAT JUN 18 2011

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS WILL BE POSSIBLE TODAY AND TONIGHT. THE GREATER CHANCES
WILL BE OVER NORTH-CENTRAL WISCONSIN TODAY THEN OVER SOUTHEAST
MINNESOTA TONIGHT. THE MAIN THREATS FROM ANY STORMS TODAY AND TONIGHT
WILL BE BRIEF HEAVY RAIN AND LIGHTNING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THUNDERSTORMS CHANCES CONTINUE SUNDAY THROUGH WEDNESDAY...WITH
SHOWERS AND THUNDERSTORMS LIKELY FOR MUCH OF THE AREA MONDAY NIGHT
THROUGH TUESDAY NIGHT. SEVERE STORMS ARE NOT ANTICIPATED SUNDAY.
THERE IS A SLIGHT RISK OF SEVERE STORMS MONDAY AND MONDAY NIGHT...
MAINLY ALONG AND SOUTH OF INTERSTATE 90. A RISK OF SEVERE STORMS
LOOKS TO CONTINUE TUESDAY INTO TUESDAY EVENING. AT THIS TIME THE
MAIN THREATS WOULD BE LARGE HAIL AND DAMAGING WINDS...HOWEVER DETAILS
ARE FAR FROM CERTAIN WITH ANY STORMS MONDAY THROUGH TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY THROUGH SUNDAY.

.EMERGENCY MANAGEMENT COORDINATION...

NO WEBINAR IS SCHEDULED.

RRS