Hail and Heavy Rain in Minnesota, June 22 to 23, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
705 PM CDT TUE JUN 22 2010

.AVIATION... /00Z TAF ISSUANCE/

SURFACE TROUGH MEANDERING FROM NEAR KDLH TO KSTC...KRWF AND KPQN
WILL DRIFT SLOWLY ESE OVERNIGHT AS LOW PRESSURE OVER NEBRASKA
MOVES TO SOUTH CENTRAL MN. THUNDERSTORM CHANCES WILL BE ON THE
INCREASE LATE THIS EVENING AND THROUGH THE EARLY MORNING HOURS FOR
PRIMARILY KRWF...KMSP AND KEAU ON SOUTHWARD AS A LARGE COMPLEX OF
STORMS IS EXPECTED TO ROLL THROUGH. INITIATION FOR THE STORMS
LOOKS TO BE UNDERWAY IN WESTERN NEBRASKA AND SOUTH CENTRAL SD ATTM
AS A STRONG UPPER LOW OVER WYOMING SHIFTS EAST. TIMING AND
INTENSITY REMAINS IN QUESTION. IT'S POSSIBLE THE COMPLEX COULD
PASS ACROSS IA AND MISS THE TAF SITES. HOWEVER...IF IT DOES MOVE
ACROSS SOUTHERN MN THERE COULD BE A PERIOD OF VERY STRONG STRAIGHT
LINE WESTERLY WINDS ALONG WITH TORRENTIAL RAIN. INCREASING NW
SURFACE WINDS ON WEDNESDAY IN THE WAKE OF THE TROUGH. SPEEDS NEAR
15 KNOTS WITH GUSTS IN THE LOW 20 KNOT RANGE FORECAST AS THE DAY
PROGRESS FROM WEST TO EAST. IT WILL REMAIN UNSTABLE TOMORROW WITH
SHOWER CHANCES AS HEATING OCCURS DURING THE DAY.

KMSP...SHOWERS WEST AND NORTH OF THE AIRPORT HAVE BEEN WEAKENING AS
BETTER THREAT FOR CONVECTION SHIFTS TO NORTHERN WI. STILL CAN'T
RULE OUT A BRIEF SHOWER POPPING UP THIS EVENING AHEAD OF THE
SURFACE TROUGH. POTENTIAL FOR STORMS MUCH BETTER AFTER MIDNIGHT.
POTENTIAL FOR A LINE TO PUSH THROUGH DURING THE EARLY MORNING
HOURS...BUT CONFIDENCE NOT HIGH. NORTHWEST WINDS INCREASING TO
12-15 KNOTS WEDNESDAY MORNING WITH GUSTS TO 20 TO 25 KNOTS.
INSTABILITY SHOWERS STILL A THREAT THROUGH MUCH OF THE DAY.

&&

.DISCUSSION... /ISSUED 114 PM CDT TUE JUN 22 2010/

THERE IS AN INCREASE POTENTIAL OF SVR WX LATER TODAY...AND INTO
THE OVERNIGHT HRS AS INSTABILITY BECOMES STRONG AND A DISTURBANCE
MOVING ACROSS THE NORTHERN PLAINS/UPPER MIDWEST INTERACTS WITH
THIS INSTABILITY TO CAUSE TSRA TO DEVELOP. AT THE PRESENT
TIME...NUMEROUS SFC BOUNDARIES HAVE FORMED DUE TO EARLY MORNING
CONVECTION ACROSS THE DAKOTAS. THIS BOUNDARY...WHICH IS ILL
DEFINED WITH MAINLY A CUMULUS FIELD BUILDING ACROSS
CENTRAL/SOUTHERN MN/EASTERN SD AS INSTABILITY INCREASES THIS AFTN.
SIGNIFICANT CAP...WHICH IS IN PLACE EARLY THIS AFTN...HAS INHIBIT ANY
RE-GENERATION OF SHRA/TSRA AS OF 1 PM. HOWEVER...LATEST SHORT TERM
MODELS DOES SHOW THE CAP ERODING ACROSS EASTERN SD/WEST CENTRAL MN
WHERE THE CURRENT 85H MAXIMUM CONVERGENCE IS NOTED.

MAIN FORECAST DILEMMA REMAINS WHERE THE MAIN CONVECTIVE COMPLEX
WILL DEVELOP THIS AFTN...AND WHERE THE LLJ/0-1KM SHEAR IS
MAXIMIZED OVERNIGHT. THIS WILL PLAY AN IMPORTANT ROLE IN THE
OVERALL SVR WX WHICH IS LIKELY TO EVOLVE OVERNIGHT ACROSS THE
PLAINS/MIDWEST. AS WITH THE CURRENT MODELS /GFS & NAM/ THE
DEPICTION OF THE SFC LOW LATER TONIGHT AND 85H JET...WILL BE THE
MAIN DILEMMA AS TO WHERE THE COMPLEX WILL DEVELOP. EVEN IF YOU
SPLIT THE DIFFERENCE BETWEEN THE TWO MODELS...FAR SOUTHERN MN
REMAINS THE MOST PROBABLE PLACE TO RECEIVE SVR WX OVERNIGHT.
CURRENT 14Z HRRR REMAINS ACTIVE IN TERMS OF RE-GENERATION OF
HIGHER REFLECTIVITY MODELING ACROSS WEST CENTRAL MN BY 21Z...WITH
THE MOVEMENT GENERALLY TO THE SOUTHEAST ACROSS EAST CENTRAL MN BY
05Z. IN ADDITION...HRRR RE-DEVELOPS A COMPLEX ACROSS WESTERN SD
WHICH MAY BE THE MAIN PLAYER OVERNIGHT AS THE AFTN TSRA SET OFF A
BOUNDARY THAT WILL LAY ACROSS FAR SOUTHERN MN OVERNIGHT. THIS
SHOULD SET THE STAGE FOR VERY HEAVY RAINFALL/STRONG WNDS AND HAIL
ALONG THE IA/MN BORDER DURING THE LATE EVENING/OVERNIGHT PERIOD.
THIS IS ALSO WHERE THE HIGHEST POPS WILL REMAIN IN THE CURRENT
FORECAST GRIDS.

AFT WEDNESDAY AFTN...THE MAIN UPPER WAVE SHOULD PAST TO THE EAST...
ALLOWING FOR STRONG SUBSIDENCE TO DEVELOP IN THE WAKE OF IT.
THEREFORE...WEDNESDAY NIGHT THRU THURSDAY LOOK TO BE THE BEST DAYS
IN TERMS OF DRY AND RELATIVELY SEASONABLE TEMPERATURES.

LATE IN THE WEEK...AND INTO THE WEEKEND...MODELS CONTINUE TO
DISPLAY A VERY UNSETTLED PATTERN WITH NUMEROUS SHRT WAVES MOVES
ACROSS THE UPPER MIDWEST. TIMING WILL REMAIN THE
PROBLEM...ESPECIALLY WITH CONVECTIVE COMPLEXES INTERFERING WITH
SFC BOUNDARIES AND ASSOCIATED INSTABILITY PARAMETERS.
THEREFORE...WILL CONTINUE HIGH CHC POPS FOR FRIDAY NIGHT...THRU
SUNDAY...BEFORE A SUBSTANTIAL UPPER RIDGE BECOMES MORE PRONOUNCED
ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST BY NEXT WEEK. ..JLT..

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH FROM 10 PM CDT THIS EVENING THROUGH WEDNESDAY
     MORNING FOR BLUE EARTH-FARIBAULT-FREEBORN-MARTIN-STEELE-
     WASECA-WATONWAN.

WI...NONE.
&&

RAH/JLT

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
719 PM CDT TUE JUN 22 2010

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
240030-
DOUGLAS-TODD-MORRISON-MILLE LACS-KANABEC-STEVENS-POPE-STEARNS-
BENTON-SHERBURNE-ISANTI-CHISAGO-LAC QUI PARLE-SWIFT-CHIPPEWA-
KANDIYOHI-MEEKER-WRIGHT-HENNEPIN-ANOKA-RAMSEY-WASHINGTON-
YELLOW MEDICINE-RENVILLE-MCLEOD-SIBLEY-CARVER-SCOTT-DAKOTA-
REDWOOD-BROWN-NICOLLET-LE SUEUR-RICE-GOODHUE-WATONWAN-BLUE EARTH-
WASECA-STEELE-MARTIN-FARIBAULT-FREEBORN-POLK-BARRON-RUSK-
ST. CROIX-PIERCE-DUNN-PEPIN-EAU CLAIRE-
719 PM CDT TUE JUN 22 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTHERN MINNESOTA...AND WEST CENTRAL WISCONSIN.

.DAY ONE...TONIGHT

THUNDERSTORMS ARE POSSIBLE ACROSS THE OUTLOOK AREA TONIGHT AS A
LOW PRESSURE SYSTEM APPROACHES FROM THE WEST. THE STORMS MAY
PRODUCE A SEVERE WIND EVENT DURING THE LATE EVENING THROUGH THE
OVERNIGHT HOURS ACROSS SOUTHERN MINNESOTA AND WEST CENTRAL
WISCONSIN AS THEY MOVE THROUGH. TORRENTIAL RAINFALL IS ALSO
POSSIBLE WITH STORMS ACROSS SOUTHERN MINNESOTA. A FLASH FLOOD
WATCH IS IN EFFECT ACROSS FAR SOUTH CENTRAL MINNESOTA.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THUNDERSTORMS REMAIN POSSIBLE ACROSS THE OUTLOOK AREA ON WEDNESDAY
WITH ANOTHER CHANCE FOR THUNDERSTORMS FRIDAY INTO SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NEEDED TONIGHT.