Hail and Damaging Winds in Minnesota, July 20 to 21, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
255 PM CDT TUE JUL 20 2004

.DISCUSSION...
WEAK LOW LEVEL CONVERGENCE ALONG WITH MINIMAL CIN AND CAPE OVER 3000
J/KG HAS ALLOWED SCT CONVECTION TO FIRE IN PTNS OF WRN WI AS
MID/HIGH LVL CLD SHIELD HAS RMND MOSTLY SW OF THIS AREA.  LOW LEVEL
SHEAR RMNS WEAK AND FREEZING LEVEL OVR 14K SO HVY RAIN MAIN PROBLEM
BUT WL NEED TO WATCH FOR WIND OR HAIL THREAT WITH STRONG UPDRAFTS.
MAIN FORECAST CHALLENGE IS CONVECTION THREAT TNGT AND WED MRNG.
FIRST S/W SWIRL PASSING SOUTH OF AREA ACRS NRN IA...WHILE SECOND S/W
TROUGH IN ERN NODAK SLIDES SE ACRS FORECAST AREA TNGT.  LID STRENGTH
WEAKENING ACRS CNTRL MN WITH RETURN OF SUNSHINE.  EXPC SCT ACTIVITY
TO FIRE LTR THIS AFTN AND EVE ACRS THIS AREA AS ENHANCED
FORCING/LIFT MOVES INTO AREA.  HAVE TO BELIEVE THAT BEST CHC FOR STG
CONVECTION AND TORNADOES ACRS SERN SD/NRN IA/NERN NE WHERE DEWPTS IN
THE MID TO UPR 70S POOLING TOWARD SFC LOW PRES IN SOUTH CENTRAL
SD...HOWEVER NEED LID TO WEAKEN THIS EVE.  SPC MESOANALYSIS SHOWS
0.3 0 TO 3KM VGP IN THIS AREA...AND EXPCD TO INCR TO .5 THIS EVE.
ZERO TO 6 KM BULK SHEAR VECTOR OF 25 TO 35 KTS COULD BE STRONGER
HWVR.  BACK TO OUR FORECAST AREA...AXIS OF DIFFERENTIAL THETA-E
ADVECTION AND Q-G FORCING SLIDES THRU CWA DURING THE EVE THROUGH 07Z
IN MN AND LATER TNGT IN WI.  CAP/LID EXPCD TO BE MUCH WEAKER AND
WITH 25 TO 35 KT LOW LEVEL JET DVLPING THIS EVE...WL BUMP UP POPS
SLIGHTLY TO LKLY CATEGORY IN ERN/SRN AREAS.  LOW LEVEL WINDS BCM
MORE WLY ON WED AS FIRST OF TWO CDFNTS MOV THRU RGN.  COOL AIR
LAGGING...SO EXPECT ONE MORE DAY OF HOT AND HUMID WEATHER BEFORE
COOLER AIR SETTLES IN FOR THE REST OF THE WEEK.  CAPE EXPECTED TO
ECLIPSE 3000 J/KG IN SRN/ERN AREAS BUT FORCING MUCH WEAKER WITH LACK
OF SYNOPTIC FORCING.  HENCE WL KEEP SML POPS IN ERN/SRN AREAS PER
PREVIOUS FORECAST.  REINFORCING CDFNT TO PUSH THRU ON THU...BUT
ATMOSPHERIC MOISTURE LIMITED.  HENCE WL CONT DRY FORECAST.

LONGER TERM...FRIDAY NIGHT THROUGH TUESDAY
A LARGE AREA OF SURFACE HIGH PRESSURE IS FORECAST BY THE GFS AND
ECMWF TO SETTLE OVER THE UPPER MISSISSIPPI VALLEY REGION FOR THE
UPCOMING WEEKEND. THE GFS THEN TRIES TO WEAKEN THE HIGH OVER OUR
AREA MONDAY THROUGH TUESDAY AS AN UPPER LOW FORMS OVER IOWA AND AN
INVERTED SURFACE TROF DEVELOPS WELL TO THE SOUTHEAST. LAST NIGHTS
ECMWF PREFERS TO KEEP THE SURFACE HIGH MORE IN PLACE OVER US EARLY
NEXT WEEK AND HAS THE UPPER LOW FORMING MORE TO THE SOUTHWEST IN
KANSAS. THEREFORE...WILL KEEP THE EXTENDED DRY WITH HIGH
TEMPERATURES A LITTLE BELOW SEASONAL NORMALS.

&&

MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.

&&

MBK/RAH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
536 AM CDT TUE JUL 20 2004

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-211030-
ANOKA-BARRON-BENTON-BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-
DOUGLAS-DUNN-EAU CLAIRE-FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-ISANTI-
KANABEC-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-
MILLE LACS-MORRISON-NICOLLET-PEPIN-PIERCE-POLK-POPE-RAMSEY-REDWOOD-
RENVILLE-RICE-RUSK-SCOTT-SHERBURNE-SIBLEY-ST CROIX-STEARNS-STEELE-
STEVENS-SWIFT-TODD-WASECA-WASHINGTON-WATONWAN-WRIGHT-YELLOW MEDICINE-
536 AM CDT TUE JUL 20 2004

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

.DAY ONE...TODAY AND TONIGHT

THE STORM PREDICTION CENTER INDICATES THAT THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER
ALL OF CENTRAL AND SOUTHERN MINNESOTA...TO INCLUDE ALL OF
WEST CENTRAL WISCONSIN. THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING
THE AFTERNOON AHEAD OF A TROUGH OF LOW PRESSURE APPROACHING FROM
THE EASTERN DAKOTAS. LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE WITH
A FEW OF THE STORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THUNDERSTORMS ARE EXPECTED AGAIN BY WEDNESDAY AFTERNOON AND
EARLY EVENING AS A VIGOROUS TROUGH OF LOW PRESSURE ADVANCES FROM
WEST TO EAST ACROSS THE REGION.  A FEW OF THE STORMS MAY BE SEVERE
WITH LARGE HAIL AND DAMAGING WINDS...MAINLY EAST OF A LINE FROM
ONAMIA...TO HUTCHINSON...TO COMFREY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON OR
EVENING...AND AGAIN BY WEDNESDAY AFTERNOON.

AZ