Flash Flood and Hail in Minnesota, May 21, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
346 AM CDT MON MAY 21 2007

.DISCUSSION...ANOMALOUS SFC HIGH PRESSURE OVER ONTARIO MAINTAINING
WEDGE OF CHILLY AIR ACROSS MOST OF CWA THIS MORNING. A SFC WARM
FRONT IS PUSHING TOWARDS THE REGION FROM SOUTHERN MN. A RAPID
RETURN FLOW IS OCCURRING ABOVE BDRY LAYER WITH MDT/STRONG
FRONTOGENESIS WITHIN THE SFC/85H LAYER. LLJ HAS ASSISTED IN
DEVELOPMENT OF ELEVATED CONVECTION THIS MORNING AS ANIMATION OF
RADAR IMAGERY...COINCIDENT WITH NAM12 85H ISOTACHS...PLACES
CURRENT CLUSTER OF DEVELOPMENT WITHIN LEFT EXIT REGION OF 85H JET.
ACTIVITY IS DEVELOPING EASTWARD ALONG MARINE BOUNDARY ACROSS SOUTH
SHORE. SOME DEEPENING OF 85/70H MSTR LYR INDICATED ON SPC
MESOANALYSIS ACROSS SRN CWA. A VERY WEAK SHORTWAVE IS CURRENTLY
PUSHING ACROSS THE APEX OF THE MID LVL RIDGE OVERHEAD...AT LEAST
ACCORDING TO MDL GUIDANCE.

EXPECT AREA OF LOW/MID LVL FRONTOGENESIS TO PUSH NE THIS MORNING
AND ACTIVITY SHOULD WANE AS OVERALL FORCING/MSTR DEPTH DECEASES.
WILL USE BROAD BRUSH AREA OF LOW POPS FOR FCST TODAY AS SW FLOW
ALOFT CONTINUES...WITH HARD TO LOCATE SHORTWAVES WIGGLING ACROSS
REGION. SOME BREAKS IN CLOUD DECK...ESPECIALLY WRN CWA THIS AFTERNOON.

TUESDAY/WEDNESDAY...SIGNIFICANT INFLUX OF MOISTURE EXPECTED AS SFC/85H FLOW
INTENSIFIES. SLOW MOVING FRONTAL SYSTEM WILL ALLOW 85/70H MSTR
FLUX ANOMALIES TO EXCEED 3 S.D. ABOVE AVERAGE SO LCLY HEAVY RAIN POSSIBLE.
UNIDIRECTIONAL FLOW SFC/85 TUESDAY AFTERNOON OVER MOST OF CWA SO
SHOULD SEE VERY BREEZY CONDITIONS...WITH G35KT AT TIMES. ALTHOUGH
SPC HAS REMOVED AREA FROM SLGHT RISK...STILL NEED TO WATCH FOR
CONVECTIVE DEVELOPMENT AS KINEMATICS SUGGEST SHEAR PROFILE WILL PROVIDE
FAVORABLE BACKGROUND ON WEDNESDAY ALTHOUGH SFC BASED STABILITY PARAMETERS
MAY BE LIMITED.

&&

.AVIATION...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WERE
OCCURRING NORTH OF A WARM FRONT THAT STRETCHED ACROSS SOUTHERN
MINNESOTA SOUTHEAST INTO ILLINOIS EARLY THIS MORNING. AREAS OF
MVFR CEILINGS WERE ALSO PRESENT ACROSS FAR NORTHERN MINNESOTA. THE
WARM FRONT WILL LIFT NORTH AND LIE ROUGHLY FROM SOUTHERN WISCONSIN
INTO NORTHWEST MINNESOTA BY EVENING. THERE WILL CONTINUE TO BE A
CHANCE FOR THUNDERSTORMS TODAY ACROSS MUCH OF THE REGION. MVFR
CEILINGS AND VISIBILITIES CAN BE EXPECTED WITH THE
STORMS...OTHERWISE CEILINGS WILL BECOME VFR THIS AFTERNOON.

A SUBSTANTIAL INVERSION WILL BE PRESENT EARLY THIS MORNING...AND
AREAS OF NON-CONVECTIVE LOW LEVEL WIND SHEAR WILL BE POSSIBLE.

&&

POINT TEMPS/POPS...
DLH  64  50  75  50 /  30  10  30  50
INL  72  55  80  55 /  20  30  60  60
BRD  80  59  79  55 /  20  10  50  60
HYR  75  55  80  57 /  20  10  20  40
ASX  70  54  81  57 /  30  10  10  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...

MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 AM CDT THIS MORNING FOR LSZ140-
     LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147.

CANNON/MELDE

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE DULUTH MN
427 AM CDT MON MAY 21 2007

LSZ121-140>148-162-MNZ010>012-018>021-025-026-033>038-WIZ001>004-
006>009-220930-
BAYFIELD TO OAK POINT WI-GRAND PORTAGE TO GRAND MARAIS MN-
GRAND MARAIS TO TACONITE HARBOR MN-
TACONITE HARBOR TO SILVER BAY HARBOR MN-
SILVER BAY HARBOR TO TWO HARBORS MN-TWO HARBORS TO DULUTH MN-
DULUTH MN TO PORT WING WI-PORT WING TO SAND ISLAND WI-
SAND ISLAND TO BAYFIELD WI-OAK POINT TO SAXON HARBOR WI-
OPEN WATERS OF LAKE SUPERIOR WEST OF A LINE FROM SAXON HARBOR WI
TO GRAND PORTAGE MN-KOOCHICHING-NORTHERN ST. LOUIS-
NORTHERN COOK/NORTHERN LAKE-NORTHERN ITASCA-CENTRAL ST. LOUIS-
SOUTHERN LAKE/LAKESHORE-SOUTHERN COOK/LAKESHORE-NORTHERN CASS-
SOUTHERN ITASCA-SOUTHERN CASS-CROW WING-NORTHERN AITKIN-
SOUTHERN AITKIN-CARLTON/SOUTHERN ST. LOUIS-PINE-DOUGLAS-BAYFIELD-
ASHLAND-IRON-BURNETT-WASHBURN-SAWYER-PRICE-
427 AM CDT MON MAY 21 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST MINNESOTA...
NORTHWEST WISCONSIN AND WESTERN LAKE SUPERIOR.

.DAY ONE...TODAY AND TONIGHT

A SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM GRAND PORTAGE SOUTH
TO THE TWIN PORTS...AND EAST TO SAXON HARBOR. NORTHEAST WINDS OF
10 TO 20 MPH WITH 3 TO 5 FOOT WAVES WILL MAKE BOATING HAZARDOUS.
PLEASE REFER TO THE LATEST MARINE FORECAST FOR ADDITIONAL DETAILS.

SCATTERED THUNDERSTORMS MAY PRODUCE GUSTY WINDS AND SMALL HAIL AT
TIMES...ESPECIALLY EARLY THIS MORNING...NEAR THE TWIN PORTS AND
EAST INTO NORTHERN WISCONSIN. ISOLATED THUNDERSTORMS ARE POSSIBLE
AGAIN THIS AFTERNOON ACROSS THE ENTIRE REGION.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SLOW MOVING FRONTAL SYSTEM WILL APPROACH THE REGION LATE TUESDAY.
VERY GUSTY WINDS...SOME IN EXCESS OF 35 MPH...MAY OCCUR TUESDAY
AFTERNOON FROM ITASCA COUNTY SOUTH TO THE BRAINERD LAKES REGION.
ABUNDANT MOISTURE IS EXPECTED AHEAD OF THE FRONT BY TUESDAY NIGHT.
THE CHANCE FOR LOCALLY HEAVY RAIN WILL INCREASE EARLY WEDNESDAY
OVER WESTERN SECTIONS AND SPREAD EASTWARD DURING THE DAY. IT IS
POSSIBLE THAT DUE TO STRENGTHENING WINDS ASSOCIATED WITH THE
SYSTEM...A FEW STRONG THUNDERSTORMS MAY DEVELOP WEDNESDAY
AFTERNOON. MUCH COOLER AIR WILL RETURN ON THURSDAY AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

CANNON