Rare October Deluge in East Central Minnesota
October 4-5, 2005

Summary

For the past four days, a stationary frontal boundary has bisected Minnesota into halves, with cooler and drier air to the north -- warmer and record-breaking muggy air to the south. This created a focal point for the formation of thunderstorms. Upper-level winds paralleled the frontal boundary, directing the thunderstorms over the same landscape over and over again.

Heavy thunderstorms began just before daybreak on October 4 and continued to develop off and on for the next 30-plus hours. A large portion of central and southern Minnesota received over two inches of rain. To put this in perspective, the normal MONTHLY October rainfall in these areas is around two inches.

Central and east central Minnesota received the most rain. Numerous reports of over four inches were reported in this area. Totals exceeding six inches were reported in portions of the following counties: Dakota, Benton, Mille Lacs, Isanti, Chisago, Kanabec, Pine and Washington A six inch rainfall total in 24 hours is considered to be a 1% probability event for a given location in a given year.

A six inch daily rainfall total in October is nearly without precedent, occurring only one other time in the historical record. The 6.61 rainfall report from Wild River State Park (Chisago county) is now the largest single-day October value reported by a National Weather Service Cooperative Observer.

Numerous non-National Weather Service observing location reported rainfall totals topping seven inches. The heaviest rainfall fell upon northern Chisago and southern Pine counties. The heavy band extended into northwestern Wisconsin. The highest total reported by a non-National Weather Service observer was 8.98 inches in Rush City. An automated rain gauge at the Rush City Airport recorded 9.59 inches. Heavy rains over six inches also fell in parts of Washington County as well with a total of 6.46 inches in north central Woodbury and 7.40 inches in southwest Woodbury.

There were sporadic reports of flooding from areas where the pockets of heavy rain were the most intense. Major road closures were common: including southbound I-35E at Highway 70 in Pine County and westbound I-494 at the Wakota Bridge in Newport. Water lapped at the doorstep of at least one home in Rush City while other homes had flooded basements. About a dozen homes were affected by a pond that overflowed in Inver Grove Heights. The lift stations in Hinckley were flooded.

It is interesting to note that a smaller event effected portions of the same area last year on October 28, 2004.

This episode will undoubtedly go down in the record books as one of the most significant October rain events on record, both in terms of spatial extent and intensity.

As always, the State Climatology Office thanks the Soil and Water Conservation Districts, the National Weather Service, and all of the diligent volunteer precipitation observers who make analyses of these events possible.


Listed below are National Weather Service Statements about the heavy rain and the subsequent impacts.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
255 PM CDT WED OCT 5 2005

...RAINFALL TOTALS FROM TUESDAY MORNING THROUGH WEDNESDAY MORNING...

THE FOLLOWING RAINFALL REPORTS ARE THE TOTALS FROM OUR DEDICATED
COOPERATIVE OBSERVERS...TRAINED SPOTTERS...AND AUTOMATED WEATHER
EQUIPMENT.

LOCATION         COUNTY        RAINFALL TOTAL IN INCHES

...IN MINNESOTA...

SPENCER BROOK    ISANTI        9.00
6 W OF CAMBRIDGE ISANTI        8.70
4 W OF CAMBRIDGE ISANTI        7.80
MORRILL          MORRISON      7.00
BURNSVILLE       DAKOTA        6.76
WILD RIVER ST PK CHISAGO       6.61
ST FRANCIS       ANOKA         6.24
MINNETONKA       HENNEPIN      6.20
W OF CAMBRIDGE   ISANTI        6.00
MORA             KANABEC       5.78
INVER GROVE HTS  DAKOTA        5.67
RICE             BENTON        5.57
WOODBURY         WASHINGTON    5.55
SW MINNEAPOLIS   HENNEPIN      5.27
CAMBRIDGE        ISANTI        5.20
STILLWATER       WASHINGTON    5.04
BECKER           SHERBURNE     4.89
ST JOSEPH        STEARNS       4.70
MPLS/ST PAUL APT HENNEPIN      4.62
SAVAGE           SCOTT         4.55
FRIDLEY          ANOKA         4.55
CARLOS AVERY     ANOKA         4.51
CLEAR LAKE       SHERBURNE     4.50
CHANHASSEN 2SW   CARVER        4.48
CHANHASSEN NWS   CARVER        4.40
SPRING PARK      HENNEPIN      4.30
GOLDEN VALLEY    HENNEPIN      4.27
S MINNEAPOLIS    HENNEPIN      4.25
MPLS LOCK/DAM    HENNEPIN      4.24
MAPLEWOOD        RAMSEY        4.18
NEW HOPE         HENNEPIN      4.18
SHERBURNE        SHERBURNE     4.18
CHASKA           CARVER        4.14
PRIOR LAKE       SCOTT         4.10
ONAMIA           MILLE LACS    4.10
ST CLOUD APT     SHERBURNE     4.07
ST PAUL APT      DAKOTA        4.01
WACONIA          CARVER        4.00
EDEN PRAIRIE APT HENNEPIN      3.95
ST CLOUD STATE   STEARNS       3.79
LITTLE FALLS     MORRISON      3.78
MILACA           MILLE LACS    3.58
NORTH ST PAUL    RAMSEY        3.56
FOREST LAKE      CHISAGO       3.52
PLYMOUTH         HENNEPIN      3.50
HIGHLAND PARK    RAMSEY        3.45
LONG PRAIRIE     TODD          2.98
GRANITE FALLS    YELLOW MED    2.97
WATERTOWN        CARVER        2.84
CARLOS           DOUGLAS       2.64
ALEXANDRIA       DOUGLAS       2.58
REDWOOD FALLS    REDWOOD       2.57
MORRIS           STEVENS       2.43
DASSEL           MEEKER        2.35
REDWOOD FALLS    REDWOOD       2.24
ROCKFORD         WRIGHT        2.06
LITCHFIELD       MEEKER        1.81
FARMINGTON       DAKOTA        1.80
HASTINGS         DAKOTA        1.60
MANKATO          BLUE EARTH    1.43
6S GRANITE FALLS YELLOW MED    1.42
MADISON          LAC QUI PARLE 1.28
AUGUSTA          CARVER        1.18
SPRINGFIELD      BROWN         1.11
VESTA            REDWOOD       1.11
MORGAN           REDWOOD       1.10
MONTGOMERY       LE SUEUR      1.10

...IN WISCONSIN...

MIKANA           BARRON        9.80
BIG FALLS HYDRO  RUSK          8.55
LADYSMITH APT    RUSK          6.29
CUMBERLAND       BARRON        5.75
2S LADYSMITH     RUSK          5.47
RIDGELAND        BARRON        3.61
AMERY            POLK          2.65
BALDWIN          ST CROIX      1.88
SPRING VALLEY    PIERCE        1.50
BLOOMER          CHIPPEWA      0.84
MENOMONIE        DUNN          0.60
EAU CLAIRE       EAU CLAIRE    0.45

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DULUTH MN
1020 AM CDT WED OCT 05 2005

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0220 AM     FLOOD            DULUTH                  46.78N 92.12W
10/03/2005                   SOUTHEAST ST. LOUI MN   NWS EMPLOYEE

MILLER CREEK IS OUT OF ITS BANKS AND WATER IS 2 INCHES
OVER SWAN LAKE ROAD

1115 AM     FLOOD            3 W ASHLAND             46.58N 90.94W
10/04/2005                   BAYFIELD           WI   PUBLIC

WATER ONE FOOT OVER ROADS AT COUNTY G AND HWY 2 NEAR THE
GREAT LAKES VISITOR CENTER. WATER IS ALSO BACKING INTO
THE VISITOR CENTER PARKING LOT.

0845 AM     FLOOD            MOQUAH                  46.57N 91.08W
10/04/2005                   BAYFIELD           WI   LAW ENFORCEMENT

SEVERAL ROADS BARRICADED AROUND AREA DUE TO FLOODING

0250 AM     FLOOD            ROCK CREEK              45.76N 92.97W
10/05/2005                   PINE               MN   LAW ENFORCEMENT

SOUTH BOUND LANE OF I-35 CLOSED FROM ROCK CREEK IN PINE
COUNTY TO HARRIS IN CHISAGO COUNTY. A FEW OTHER ROADS IN
PINE COUNTY ARE ALSO CLOSED DUE TO FLOODING.

0253 AM     FLOOD            GRANTSBURG              45.78N 92.68W
10/05/2005                   BURNETT            WI   LAW ENFORCEMENT

MANY ROADS CLOSED INCLUDING SECTIONS OF HWY 48.

0257 AM     FLOOD            RADISSON                45.77N 91.22W
10/05/2005                   SAWYER             WI   LAW ENFORCEMENT

HWYS H AND 27/70 CLOSED NEAR RADISSON. SECTIONS OF HWY 48
CLOSED IN SOUTH PARTS OF COUNTY.

0732 AM     FLOOD            MOQUAH                  46.57N 91.08W
10/05/2005                   BAYFIELD           WI   LAW ENFORCEMENT

COUNTY HWY G CLOSED

0732 AM     FLOOD            1 W WASHBURN            46.67N 90.91W
10/05/2005                   BAYFIELD           WI   LAW ENFORCEMENT

PORTIONS OF HWY 13 DOWN TO ONE LANE NEAR CHERRYVILLE

0845 AM     FLOOD            HINCKLEY                46.01N 92.94W
10/05/2005                   PINE               MN   CO-OP OBSERVER

HINKLEY LIFT STATIONS FLOODED

0745 AM     FLOOD            GRANTSBURG              45.78N 92.68W
10/05/2005                   BURNETT            WI   LAW ENFORCEMENT

MANY FLOODED ROADS IN GRANTSBURG AND AROUND COUNTY. SOME
CULVERTS WASHED OUT

0745 AM     FLOOD            SPOONER                 45.82N 91.89W
10/05/2005                   WASHBURN           WI   LAW ENFORCEMENT

PART OF HWY 253 WASHED OUT. LOCALIZED FLOODING ON OTHER
ROADS. RISING WATERS ON LAKE HAS CAUSED A PONTOON BOAT TO
FLOAT INTO A YARD.

0745 AM     FLOOD            RADISSON                45.77N 91.22W
10/05/2005                   SAWYER             WI   LAW ENFORCEMENT

SEVERAL ROADS FLOODED WITH UP TO A FOOT OF WATER AROUND
COUNTY.

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URL: http://climate.umn.edu/doc/journal/flash_floods/ff051004-05.htm
Last modified: November 10, 2005