Heavy Rain in Minnesota, May 6, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
605 AM PM CDT WED MAY 6 2009

.UPDATED FOR AVIATION DISCUSSION BELOW...

.DISCUSSION...
SHORTWAVE TROF MOVING ACROSS CENTRAL MINNESTOA WITH CLEARING IN ITS
WAKE. CONVECTION CONTINUES TO OUR S ACROSS N IA IN BAND OF ELEVATED
INSTABILITY AHEAD OF SHORTWAVE MOVING ACROSS CENTRAL NEBRASKA. THIS
FEATURE MOVES ACROSS IOWA DURING THE DAY SO WILL KEEP POPS GOING
THRU DAY IN SC MN.  RATHER VIGOROUS SHORTWAVE MOVING ACROSS E MT IS
PROGGED TO REACH THE W MN BORDER BY 00Z AND THEN REACH THE WI BORDER
BY AROUND 06Z.  THIS FEATURE CARRIES A SURFACE FRONT INTO W MN THIS
MORNING AND THEN INTO E MN BY 00Z.  NAM AND GFS BOTH DEVELOP AROUND
1000 J/KG SBCAPE E CWA THIS AFTERNOON. 0-6KM BULK SHEAR FAIRLY WEAK
THRU MOST OF THE DAY AND DOESNT SHOW SUBSTANTIAL INCREASE UNTIL
THIS EVENING IN WAKE OF SURFACE TROF. WITH RATHER STRONG MID LEVEL
LAPSE RATES WITH COOL 500 MB AIR WILL PROBABLY SEE SOME HAILERS
AGAIN MAINLY EASTERN CWA.  SHOULD BE ENUF SUN TODAY FOR TEMPS MAINLY
IN THE 70 TO 75 DEGREE RANGE WITH AIRMASS AT LEAST AS WARM AS IT WAS
YESTERDAY. MIXING IN WAKE OF SURFACE TROF SHOULD YIELD SOME GUSTS
AROUND 25 MPH THIS AFTERNOON ACROSS WESTERN AREAS.

SHOWERS/TSTMS WILL END IN ALL BUT THE FAR EAST BY EARLY EVENING WITH
PASSAGE OF UPPER TROF.

ANOTHER FAST MOVING UPPER TROF MOVES ACROSS NEBRASKA AND IOWA ON
THURSDAY BRINGING A SMALL CHANCE OF SHOWERS TO FAR SC MN.  IF CLOUDS
DONT THICKEN UP TOO MUCH COULD BE A BIT INTERESTING FIRE
WEATHER-WISE WITH GUSTY WESTERLY WINDS AHEAD OF APPROACHING COLD
FRONT DROPPING ACROSS N MN BRINGING IN PRETTY DRY AIR OUT OF THE
DAKOTAS ACROSS MN/WI.

SIGNIFICANT DIFFERENCES BETWEEN GFS/NAM FOR FRIDAY WITH GFS STRONGER
AND FASTER ON SPREADING SHOWERS/THUNDERSTORMS ACROSS AREA WITH UPPER
LOW TRACKING FARTHER SOUTH. ECMWF NOT AS AGGRESSIVE AS EITHER U.S.
MODEL WITH LESS QPF OUTPUT...BUT STILL BRINGS A SWATH OF RAIN ACROSS
S AREAS.  BUMPED UP POPS A BIT FOR FRIDAY/FRIDAY NIGHT. MUCH COOLER
IN THE WAKE OF THIS STRONG TROF WITH 850 MB TEMPS DROPPING TO ZERO
INTO S MN. ALSO LOWERED TEMPS SEVERAL DEGREES FOR SATURDAY AND PUT
SMALL POPS IN FOR SATURDAY ACROSS ABOUT N 1/2 CWA UNDER COLD UPPER
TROF.

&&

.AVIATION.../06Z TAF ISSUANCE/
MAIN FORECAST CONCERN TODAY IS TIMING OF CONVECTION OVER FA.  MODELS
IN SOME AGREEMENT IN LIFTING INSTABILITY AXIS OVER EASTERN FA AHEAD
OF INCOMING SURFACE TROUGH OVER THE EASTERN DAKOTAS.  APPEARS KMSP
WILL BE ON THE EDGE OF THIS ACTIVITY...WITH PERHAPS KRNH/KEAU HAVING
BETTER CHANCE OF SEEING -TSRA THIS AFTERNOON.  09Z RUC13 A LITTLE
SLOWER WITH MOVEMENT OF TROUGH THEREBY GIVING KMSP A BETTER CHANCE
OF SEE SCT -TSRA AS WELL.  WILL CONTINUE TREND OF VCSH/CB AND WILL
MENTION PROB30 AT THE WI TAF SITES.  FARTHER WEST...MAY SEE SOME
-SHRA/ISOLD -TSRA DEVELOP HERE DURING THE AFTERNOON...AS MORE
WESTERLY FLOW DEVELOPS.  WILL MENTION VCSH AT THESE SITES AS WELL.
IMMEDIATE CONCERN...IS POSSIBILITY OF MVFR FOG AT A FEW SITES WHERE
TEMP/DP SPREADS ARE LOW. THIS WILL BURN OFF QUICKLY THROUGH 14Z
ACROSS REGION.

&&

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

BAP/DWE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
408 AM CDT WED MAY 6 2009

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
070915-
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-
408 AM CDT WED MAY 6 2009

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

.DAY ONE...TODAY AND TONIGHT

A TROUGH OF LOW PRESSURE WILL MOVE ACROSS MINNESOTA TODAY
ARRIVING IN WESTERN WISCONSIN EARLY THIS EVENING. SCATTERED
THUNDERSTORMS AHEAD OF THE FRONT THIS AFTERNOON AND EARLY EVENING
MAY PRODUCE HAIL AND STRONG WINDS. A SLIGHT RISK OF SEVERE
THUNDERSTORMS INCLUDES SOUTH CENTRAL AND EAST CENTRAL MINNESOTA
INTO WESTERN WISCONSIN. THIS WOULD ENCOMPASS THE TWIN CITIES METRO
AREA AS WELL AS AREAS FROM FAIRMONT TO ALBERT LEA AND EAU CLAIRE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

UNSETTLED WEATHER WILL CONTINUE INTO SATURDAY. AN STRONG AREA OF
LOW PRESSURE MAY PRODUCE A FEW THUNDERSTORMS ON FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EARLY
EVENING.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1100 AM CDT WED MAY 6 2009

MNZ083>085-061745-
BLUE EARTH-STEELE-WASECA-
1100 AM CDT WED MAY 6 2009

...HEAVY RAIN JUST SOUTH OF HIGHWAY 14 IN SOUTHERN MINNESOTA...

AT 1157 AM CDT...RADAR INDICATED THAT THUNDERSTORMS CONTINUED TO
DEVELOP FROM FAR EASTERN BLUE EARTH COUNTY ACROSS CENTRAL WASECA AND
STEELE COUNTIES OR FROM EAST OF MAPLETON TO PEMBERTON TO ABOUT
WASECA TO BETWEEN OWATONNA AND STEELE CENTER. THESE STORMS WERE
MOVING VERY SLOWLY NORTHWARD WITH REPEATED DEVELOPMENT TAKING PLACE
OVER THESE AREAS. RAINFALL RATES OF 0.75 TO 1.25 INCHES IN ONE HOUR
ARE POSSIBLE WITH THESE STORMS AS THE SLOWLY MOVE NORTHWARD TOWARDS
HIGHWAY 14. PONDING OF WATER ON ROADWAYS AND LOW SPOTS IS POSSIBLE.
HEAVY RAIN ON THE ORDER OF ONE INCH PER HOUR HAS BEEN REPORTED SOUTH
OF ST. CLAIR IN BLUE EARTH COUNTY.

PEA SIZE HAIL IS ALSO POSSIBLE WITH THESE STORMS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

RAINFALL AMOUNTS OF 1 TO POSSIBLY 2 INCHES ARE POSSIBLE FROM THESE
STORMS. THIS MAY RESULT IN BRIEF RUNOFF PROBLEMS AND PONDING OF
WATER ON AREA ROADWAYS.

&&

MDB