Special Weather Statement, NWS Twin Cities, MN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1040 PM CDT TUE JUN 22 2010

.AVIATION... /06Z TAF ISSUANCE/

CONFIDENCE HIGH THAT A CONVECTIVE COMPLEX WITH DAMAGING WINDS
WILL PASS ACROSS SOUTHERN MN BETWEEN 07Z AND 11Z. THIS WOULD
PRIMARILY AFFECT KRWF. HOW FAR NORTH THE BOW WILL EXTEND IS STILL
IN QUESTION...BUT KMSP AND KRNH WILL LIKELY BE ON THE NORTH END.
HAVE INSERTED A STRONG WESTERLY WIND GROUP IN THE KRWF TAF FOR THE
ANTICIPATED BOW. PROBABILITY FOR STORMS LOWER FOR KSTC AND KAXN.
KEAU WILL ALSO BE ON THE RECEIVING END OF THE POTENTIAL BOW TOWARD
DAYBREAK...BUT STRONG CONVECTION WITH HAIL POTENTIAL MAY PUSH IN
BEFORE FROM SE MN WHICH REPRESENTS STRONG MOISTURE TRANSPORT. IN
THE WAKE OF THE CONVECTIVE COMPLEX...WINDS WILL TURN NW WEDNESDAY
MORNING WITH SPEEDS INCREASING TO 12-15 KNOTS WITH GUSTS IN THE 20
TO 25 KNOT RANGE. CLEARING SKIES BY WEDNESDAY EVENING ALONG WITH
DIMINISHING WIND.

KMSP...CONVECTION ACROSS SD AND NE EXPECTED TO CONSOLIDATE INTO A
FORWARD PROPAGATING COMPLEX IN THE NEXT FEW HOURS AND ADVANCE
ACROSS SOUTHERN MN DURING THE OVERNIGHT HOURS. DAMAGING STRAIGHT
LINE WINDS EXPECTED...BUT HOW FAR NORTH THEY MAKE IT STILL IN
QUESTION. FOR NOW...HAVE INSERTED WEST WINDS AT 25 KNOTS GUSTING
TO 40 KNOTS INTO THE KMSP TAF BETWEEN 09Z AND 11Z. SCATTERED
SHOWERS EXPECTED WEDNESDAY MORNING IN THE WAKE OF THE CONVECTIVE
COMPLEX AS AN UPPER TROUGH PASSES THROUGH. NW WINDS INCREASING AS
WELL IN THE MORNING WITH 15 KNOTS GUSTING TO 25 KNOTS. DIMINISHING
WIND AND CLOUDS WEDNESDAY EVENING.

&&

.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 UNTIL 10 AM CDT WEDNESDAY 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.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1136 PM CDT TUE JUN 22 2010

MNZ091-092-230515-
FARIBAULT-MARTIN-
1136 PM CDT TUE JUN 22 2010

...THUNDERSTORMS DEVELOPING OVER FARIBAULT AND SOUTHEAST MARTIN
COUNTIES THROUGH 1215 AM CDT...

AT 1131 PM CDT...WEATHER SERVICE RADAR WAS TRACKING A STRONG
THUNDERSTORM 11 MILES WEST OF ELMORE. THIS STORM WAS MOVING EAST AT
25 MPH. MORE THUNDERSTORMS...CAPABLE OF BEING SEVERE...ARE EXPECTED
TO CONTINUE TO REDEVELOP THROUGH THE NIGHT OVER SOUTH CENTRAL
MINNESOTA.

HAIL UP TO DIME SIZE IS EXPECTED WITH THIS CURRENT STORM.

* LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  EAST CHAIN.
  ELMORE.
  BLUE EARTH.
  FROST.
  INTERSTATE 90.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS THUNDERSTORM COULD INTENSIFY QUICKLY...SO BE READY TO ACT IF A
WARNING IS ISSUED.

&&

LAT...LON 4359 9446 4382 9366 4349 9366 4349 9445
      4350 9445
TIME...MOT...LOC 0436Z 248DEG 23KT 4353 9427