Hail and Damaging Wind in Minnesota, August 6, 2008

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1127 AM CDT WED AUG 6 2008

.UPDATE...

.DISCUSSION...
GOING FORECAST FOR THIS AFTN LOOKS PRETTY MUCH ON TRACK. GOES WV
LOOP THIS LATE MORNING SHOWING A NICE SHORT WAVE WITH ASSOCIATED
PV ANOMALY DROPPING SOUTHEAST ACROSS NRN MN. NARROW RIBBON OF
SUPPRESSION BETWEEN THIS AND MID-LEVEL FRONTOGENETIC FORCING ACROSS
NRN IA AND SRN MN. THE LIGHT RAIN IN SRN MN SHOULD SCOOT
SOUTHWARD SOON INTO THE AFTN. BUT THE SHORTWAVE UPSTATE MN WILL
LIKELY PROMOTE THE DEVELOP OF SCT SHOWERS AND T-STORMS SOON INTO
THE AFTN ACROSS PRIMARILY ERN MN AND WRN WI. DIAGNOSTIC MODELS
AND ACARS SOUNDINGS INDICATING STEEP LAPSE RATES IN THE 850-500MB
LAYER IN RESPONSE TO THE COOLING MID-LEVELS. THIS YIELDS TALL
NARROW CAPE IN THIS CORRIDOR...APPROX 500-1200 J/KG PREDICTED BY
THE 15Z RUC FOR THIS AFTN FROM ERN MN INTO WRN WI. THIS SEEMS
REASONABLE WITH FORECASTED MAX TEMPS AND TDS THIS AFTN AND
CURRENT TRENDS. SFC RESPONSIVE COLD FRONT SHOWING UP IN THE OBS
UPSTREAM...AIDING A LITTLE MORE IN COVERAGE AND POOLING OF
AFOREMENTIONED CAPE VALUES. SO HAVE BUMPED UP POPS SLIGHTLY IN WRN
WI. THINK WINDOW OF TIME FOR SCT CONVECTION IN OUR FORECAST AREA
SHOULD MAINLY BE 1 PM TO 5 PM. SVR THREAT LOOKS MINIMAL DUE TO THE
MARGINAL INSTABILITY AND MOISTURE. COOL POCKET ALOFT THOUGH
YIELDING WET BULB ZERO HEIGHTS NEAR 10 KFT THIS AFTN IN WRN
WI...PRETTY LOW ESPECIALLY COMPARED TO RECENTLY. SO SOME SMALL
HAIL POSSIBLE WITH ANY T-STORMS. UNIDIRECTIONAL NWRLY PROFILE
WOULD FAVOR SOME WINDS IN T-STORMS...BUT MORE SO ONCE CLUSTERED.
WOULD THINK A LITTLE BETTER CHANCE OF THAT INTO CTRL WI. TEMPS
LOOK ON TRACK FOR THIS AFTN.

&&

.PREV DISCUSSION...
/ISSUED 626 AM CDT WED AUG 6 2008/

A COUPLE OF AREAS OF FORCING WILL AFFECT PARTS OF THE CWA TODAY.
CONVECTION OVER THE DAKOTAS IN A REGION OF MID LEVEL INSTABILITY
WITH THE GRADIENT ACROSS NORTHERN SD. THIS REGION ALSO UNDER THE
RIGHT ENTRANCE REGION OF THE UPPER JET EXTENDING ACROSS ND INTO
CENTRAL MN. SOME OF THIS PRECIP MAY BRUSH OUR FAR SW AREAS THIS
MORNING. SECONDLY...SHORT WAVE IN THE NW FLOW HEADING TOWARD ND
AND NORTHERN MN. NAM SEEMS TO HAVE HANDLE ON THE VORT PATTERN.
BEST FORCING FROM THIS WILL PASS JUST TO OUR NORTH...BUT SHOULD
BE ENOUGH INSTABILITY TO CAUSE A FEW SHOWERS OR TSTMS OVER OUR
AREA THIS AFTERNOON INTO THE EVENING. GFS MOS SEEMS A LITTLE LOW
FOR HIGH TEMPS...SO WILL GO CLOSER TO MET/FWC. SHOULD BE DECENT
SINKING BEHIND THE FRONT AND TROUGH SO THE CURRENT MOSTLY CLEAR
SKY GRIDS LOOK GOOD. WILL BRING CLEARING IN A LITTLE EARLIER
OVERNIGHT THOUGH. REST OF THE WEEK AND INTO THE FIRST PART OF THE
WEEKEND LOOK DRY WITH THE NORTHWEST FLOW PROVIDING TEMPS NEAR OR
JUST A TOUCH BELOW NORMAL. THE END OF THE WEEKEND AND EARLY NEXT
WEEK A LITTLE IN QUESTION. THE ECMWF HAS BEEN SHOWING A TREND OF
THE RIDGE FLATTENING THE LAST FEW RUNS...WITH A WAVE AFFECTING
PARTS OF THE AREA. COULD BE POTENTIAL FOR A SPLIT THOUGH...WITH
BETTER MOISTURE TRANSPORT JUST TO OUR SOUTH. WILL INTRODUCE A
SMALL POP FOR THIS ON SUNDAY. THERE IS ALSO A FAIR AMOUNT OF
SPREAD BETWEEN MIN AND MAX TEMPS IN THE ENSEMBLE OUTPUT FOR SUNDAY
INTO TUESDAY...PROBABLY DUE TO THE UNCERTAINTY IN THE STRENGTH OF
THE RIDGE OVER MIDDLE PART OF THE CONUS.

&&

.AVIATION.../18Z TAF ISSUANCE/

SCT SHRA WITH SOME -TSRA EXPECTED IN WRN WI THIS AFTN WITH ISOLD
COVERAGE IN ERN MN. THIS IS IN RESPONSE TO A MID-LEVEL
DISTURBANCE DROPPING SOUTHEAST ACROSS THE FORECAST AREA. STEEP
LAPSE RATES SHOULD FAVOR THE QUICK DEVELOPMENT OF ISOLD TO SCT
SHOWERS BETWEEN 18Z AND 20Z IN CTRL MN TO NWRN WI. THIS WOULD BE
WHERE A SFC TROUGH IS DROPPING SOUTHEASTWARD CAUSING A WIND SHIFT
FROM WRLY TO A MORE PREDOMINATE NWRLY. AS THIS PROPAGATES
SOUTHEAST THERE WILL BE POTENTIAL FOR SOME THUNDER GIVEN
CONVECTIVE INDICES. COVERAGE OF SHOWERS SHOULD BE 20 TO 40
PERCENT FROM RNH TO EAU FROM 19Z TO 22Z OR SO. SOME SMALL HAIL
POSSIBLE ALONG WITH A BRIEF GUSTY WIND UNDER ANY T-STORMS.
DEVELOPMENT FURTHER WESTWARD TOWARDS AXN...RWF...AND STC SEEMS
MINIMAL WITH SUPPRESSION ALOFT...BUT THERE IS A SMALL CHANCE.
WINDS THIS AFTN WILL ALSO OCCASIONALLY GUST TO 15 TO 17 KTS JUST
DUE TO MIXING WITH UNIDIRECTIONAL NWRLY FLOW ALOFT. SKIES SHOULD
BECOME CLEAR THIS EVENING AND ESPECIALLY SO OVERNIGHT. VFR DRY
CONDITIONS WITH GENTLE NRLY FLOW THEN LOOK TO PREVAIL ALL THE WAY
INTO SAT.

&&

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

JPR/MTF

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1208 PM CDT WED AUG 6 2008

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
071100-
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-
1208 PM CDT WED AUG 6 2008

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

IN RESPONSE TO A SURFACE TROUGH MOVING THROUGH MINNESOTA AND
WISCONSIN...ISOLATED TO SCATTERED THUNDERSTORMS WILL TRAVERSE
SOUTHEAST ACROSS EASTERN MINNESOTA AND WESTERN WISCONSIN THIS
AFTERNOON. SMALL HAIL WILL BE LIKELY FROM STRONGER
THUNDERSTORMS...WITH A SMALL CHANCE FOR A SEVERE STORM WITH
QUARTER SIZE HAIL AND GUSTY WINDS. THE THUNDERSTORMS WILL MOVE OUT
OF THE OUTLOOK AREA BY 6 PM.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SHOWERS AND THUNDERSTORMS ARE POSSIBLE LATE SATURDAY NIGHT INTO
THE BEGINNING OF NEXT WEEK AS LOW PRESSURE DEVELOPS FROM THE
NORTHERN PLAINS INTO THE MIDWEST. AT THIS TIME...THUNDERSTORMS ARE
EXPECTED TO REMAIN BELOW SEVERE LIMITS.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION IS NOT ANTICIPATED THIS AFTERNOON...BUT
ANY REPORTS OF HAIL RECEIVED WILL BE APPRECIATED.