On January 28th, a strengthening low pressure system moving northeast across the Dakotas and northern Minnesota brought much above normal temperatures (high temperatures in the 40s) across the Upper Mississippi River Valley Region.  At midnight on January 29th, the temperatures still ranged from the mid 30s to lower 40s.  Then a very drastic weather change came about as a very strong arctic cold front moved across the area during the morning of January 29th.  This brought dangerous winter weather conditions to the region, in the form of snow, strong winds, blowing snow and blizzards, along with bitterly cold temperatures and wind chills. 

During the morning hours on January 29th, the front had moved from eastern Minnesota and eastern Iowa, into eastern Wisconsin and northwest Illinois.  This front brought a switch in wind direction from south to northwest and temperatures began to drop.  However, the coldest air and strongest winds lagged behind the front by about 100 miles.  As the day progressed the entire system moved east and temperatures dropped at a rate of 2 to 5 degrees per hour.  By 10:00 PM, actual temperatures in the local area ranged from around 10 degrees below zero in parts of southeast Minnesota to around zero in southeast Wisconsin.

As the temperatures dropped, northwest winds increased and by mid morning were blowing at 20 to 30 miles per hour.  These winds combined with the cold temperatures to cause wind chills during the day from the teens below zero to around 35 degrees below zero.  The strong winds also caused problems when an area of moderate to heavy snow moved from Iowa across southeast Minnesota and into central Wisconsin.  While accumulations were not significant, generally in the 1 to 4 inch range, blowing snow brought blizzard conditions along a narrow corridor from north central Iowa through parts of southeast Minnesota into west central Wisconsin.  Visibilities in these areas dropped down to zero at times, and combined with the very cold wind chills, created dangerous situations for anyone traveling or just being outside in general.

The winds strengthened even further during the late afternoon as the strong low pressure system moved northeast across northern Illinois and Lake Michigan.  At 4 PM, Chicago reported a barometric pressure reading of  29.06 inches.  This was their lowest pressure reading since January 10, 1975 (33 years).  The tight surface pressure gradient associated with this low pressure area caused the winds to increase into the 25 to 35 mph range from the afternoon of January 29th into the early morning hours of January 30th.  During this same time period, the winds gusted up into the 35 to 50 mph range.

Drastic Temperature Drop

On January 29th, an arctic cold front moved through southeast  Minnesota and northeast Iowa between 1:00 AM and 5:00 AM, and through western Wisconsin between 5:00 AM and 10:00 AM.  The temperatures behind this cold front dropped between 2 and 5 degrees per hour through the morning and afternoon.  By 4 PM, temperatures had dropped between 30 and 45 degrees from their early morning high temperatures.  These temperatures would continue to drop about another ten degrees through midnight.  For the calendar day, the temperature drop ranged from 41 degrees at Oelwein, IA to 56 degrees at Winona State University in Winona, MN.  The last time that the area saw a temperature change this great on a calendar day was January 18, 1996. 

The table below provides the temperature change on January 29th.

          Temperature Change on January 29, 2008

In Northeast Iowa...

                                        Temp   High    Low
Location                    County      Fall   Temp    Temp
--------                    ------      ----   ----    ----
Cresco KIMT                 Howard       53     40     -13
Crestwood AWS               Howard       52     41     -11
Decorah AWOS                Winneshiek   51     43      -8
Turkey Valley AWS           Chickasaw    50     39     -11
Osage - KIMT                Mitchell     49     39     -10
New Hampton AWS             Chickasaw    48     36     -12
Riceville - KIMT            Howard       48     37     -11
Charles City AWOS           Floyd        43     37      -6
Oelwein AWOS                Fayette      41     37      -4

In Southeast Minnesota...

                                        Temp   High    Low
Location                    County      Fall   Temp    Temp
--------                    ------      ----   ----    ----
WSU Campus                  Winona       56     43     -13
Rochester Kellogg - KIMT    Olmsted      55     40     -15
Willow Creek - KIMT         Olmsted      55     41     -14
Century High School AWS     Olmsted      54     37     -17
Preston KIMT                Fillmore     54     41     -13
Rochester Lincoln AWS       Olmsted      54     38     -16
Plainview AWS               Wabasha      53     37     -16
St Charles 4W RWIS          Olmsted      53     40     -13
Grand Meadow - KIMT         Mower        52     37     -15
Preston AWOS                Fillmore     52     41     -11
Rochester ASOS              Olmsted      52     40     -12
Winona AWOS                 Winona       52     43      -9
Austin KIMT                 Mower        51     37     -14
Byron/Kasson RWIS           Dodge        50     37     -13
West Concord - KIMT         Dodge        50     35     -15
Austin AWOS                 Mower        48     39      -9
Albert Lea - KIMT           Freeborn     48     38     -10
Dexter RWIS                 Mower        48     36     -12
Dodge Center AWOS           Dodge        48     37     -11

In Western Wisconsin...

                                        Temp   High    Low
Location                    County      Fall   Temp    Temp
--------                    ------      ----   ----    ----
Richland Center AWS         Richland     55     42     -13
Wisc Dells AWOS             Sauk         54     43     -11
Alma AWS                    Buffalo      53     37     -16
Fennimore Elementary AWS    Grant        53     41     -12
Friendship AWS              Adams        53     39     -14
La Crosse ASOS              La Crosse    53     43     -10
Prairie Du Chien AWS        Crawford     53     43     -10
Riverdale School AWS        Grant        53     42     -11
Arcadia Hill RWIS           Trempealeau  52     40     -12
Black River Falls RAWS      Jackson      52     40     -12
La Crosse - NWS             La Crosse    52     40     -12
Loyal School AWS            Clark        52     38     -14
Tomah 4N RWIS               Monroe       52     43      -9
Jackson Pass 5W Tomah RWIS  Monroe       51     42      -9
Mount Sterling 1S RWIS      Crawford     51     41     -10
Necedah RAWS                Juneau       51     42      -9
Dickeyville RWIS            Grant        50     45      -5
Boscobel ASOS               Grant        49     43      -6
Prairie Du Chien AWOS       Crawford     49     41      -8
Sparta AWOS                 Monroe       49     41      -8
Stanley 1 SE RWIS           Chippewa     49     37     -12
Medford AWOS                Taylor       48     37     -11

La Crosse, WI saw the temperature drop from a high temperature of 43 degrees at 2:03 AM to a low temperature of -10 degrees at 11:49 PM.  This 53 degree temperature change tied February 17, 1874 for the largest temperature change during a calendar day.

Rochester, MN fell from 40 degrees at 12:01 AM to -12 degrees at 11:13 PM.  This 52 degree drop tied January 20, 1937 and February 23, 1918 for their sixth largest temperature change in a calendar day.  It was their largest change in temperature since January 18, 1996 when the temperature fell 50 degrees.  Their largest temperature difference ever recorded was 58 degrees on May 5, 1909.

The image below provides the hourly temperature fall at Rochester International Airport, La Crosse Municipal Airport, and Necedah Wildlife Reserve.

Strong Winds

Behind the arctic cold front during the morning of January 29th, the northwest winds increased into the 20 to 30 mph range.  This caused considerable blowing and drifting of the snow in southeast Minnesota and parts of northeast Iowa and west central Wisconsin.  Blizzard conditions existed in these areas during the late morning and afternoon.  These winds increased into the 25 to 35 mph range during the late afternoon and continued into the early morning hours of January 30th.  It was during this time that many of the peak wind gusts were reported.  The table below lists the peak wind gusts from the afternoon of January 29th through the morning of January 30th.

                                                Peak Wind Gusts

IN NORTHEAST IOWA...

STATION                   COUNTY             TIME     GUST
-------                   ------             ----     ----
OELWEIN AWOS              FAYETTE           255 PM   47 MPH
CHARLES CITY AWOS         FLOYD             715 PM   45 MPH
DECORAH AWOS              WINNESHIEK        755 PM   36 MPH

IN SOUTHEAST MINNESOTA...

STATION                   COUNTY             TIME     GUST
-------                   ------             ----     ----
DEXTER RWIS               MOWER             726 PM   53 MPH
BYRON/KASSON RWIS         DODGE             259 PM   46 MPH
ST CHARLES 4W RWIS        OLMSTED           621 PM   46 MPH
ROCHESTER ASOS            OLMSTED           654 PM   46 MPH
PRESTON AWOS              FILLMORE          715 PM   44 MPH
DODGE CENTER AWOS         DODGE             515 PM   38 MPH
WINONA AWOS               WINONA            217 PM   33 MPH

IN WESTERN WISCONSIN...

STATION                   COUNTY             TIME     GUST
-------                   ------             ----     ----
VOLK FIELD                JUNEAU           1123 PM   43 MPH
MOUNT STERLING 1S RWIS    CRAWFORD         1008 PM   43 MPH
PRAIRIE DU CHIEN AWOS     CRAWFORD          455 PM   41 MPH
STANLEY 1 SE RWIS         CHIPPEWA         1003 PM   39 MPH
TOMAH 4N RWIS             MONROE            907 PM   39 MPH
ARCADIA HILL RWIS         TREMPEALEAU       710 PM   38 MPH
NECEDAH RAWS              JUNEAU            848 PM   38 MPH
MEDFORD AWOS              TAYLOR            755 PM   38 MPH
DICKEYVILLE RWIS          GRANT             803 PM   36 MPH
LA CROSSE ASOS            LA CROSSE         853 PM   36 MPH
BOSCOBEL ASOS             GRANT             817 PM   36 MPH
JACKSON PASS 5W TOMAH     MONROE            909 PM   35 MPH
WISC DELLS AWOS           SAUK             1035 PM   35 MPH
SPARTA AWOS               MONROE            835 PM   33 MPH

KEY TO OBSERVATION TYPES
AWS - SENSORS FROM AWS INCORPORATED. OFTEN LOCATED AT SCHOOLS.
RWIS - ROAD WEATHER INFORMATION SYSTEMS. LOCATED ON MAJOR ROADS AND BRIDGES.
RAWS - FIRE WEATHER OBSERVATIONS. OFTEN LOCATED IN FORESTS.
ASOS/AWOS - AVIATION WEATHER OBSERVATIONS. LOCATED AT AIRPORTS.
OBSERVATIONS ARE COLLECTED FROM A VARIETY OF SOURCES WITH VARYING EQUIPMENT
AND EXPOSURE.  NOT ALL DATA LISTED IS CONSIDERED OFFICIAL.

Very Dangerous Wind Chills

Very dangerous wind chills developed across southeast Minnesota, northeast Iowa, and western Wisconsin during the early evening of January 29th and continued through the morning of January 30th.  Wind chills generally ranged from 30 to 45 degrees below zero.  The table below provides the lowest wind chills from the afternoon of January 29th through the morning of January 30th. 




                                                Lowest Wind Chills

IN NORTHEAST IOWA...

STATION                   COUNTY             TIME   WIND CHILL
-------                   ------             ----   ----------
MFL MARMAC ES/HS MONONA   CLAYTON           859 PM    -43 F
NEW HAMPTON AWS           CHICKASAW        1114 PM    -37 F
TURKEY VALLEY AWS         CHICKASAW         844 PM    -37 F
RICEVILLE - KIMT          HOWARD            816 PM    -36 F
CRESTWOOD AWS             HOWARD           1014 PM    -35 F
CHARLES CITY AWOS         FLOYD             955 PM    -35 F
OELWEIN AWOS              FAYETTE           835 PM    -33 F
OSAGE - KIMT              MITCHELL          756 PM    -32 F
DECORAH AWOS              WINNESHIEK        955 PM    -30 F

IN SOUTHEAST MINNESOTA...

STATION                   COUNTY             TIME   WIND CHILL
-------                   ------             ----   ----------
CENTURY HIGH SCHOOL AWS   OLMSTED          1014 PM    -46 F
GRAND MEADOW - KIMT       MOWER             855 PM    -46 F
DEXTER RWIS               MOWER             721 PM    -45 F
ST CHARLES 4W RWIS        OLMSTED           856 PM    -43 F
WEST CONCORD - KIMT       DODGE             835 PM    -42 F
PRESTON KIMT              FILLMORE          915 PM    -40 F
JOHN ADAMS - KIMT         OLMSTED           936 PM    -40 F
PRESTON AWOS              FILLMORE         1135 PM    -40 F
AUSTIN AWOS               MOWER             756 PM    -39 F
AUSTIN KIMT               MOWER             756 PM    -39 F
DODGE CENTER AWOS         DODGE             755 PM    -38 F
ROCHESTER LINCOLN AWS     OLMSTED           900 PM    -37 F
WSU CAMPUS                WINONA           1144 PM    -37 F
PLAINVIEW AWS             WABASHA           914 PM    -36 F
WINONA AWOS               WINONA            957 PM    -33 F
3N LA CRESCENT APRS       HOUSTON           232 AM    -29 F

IN WESTERN WISCONSIN...

STATION                   COUNTY             TIME   WIND CHILL
-------                   ------             ----   ----------
FRIENDSHIP AWS            ADAMS             559 AM    -44 F
MEDFORD AWOS              TAYLOR           1255 AM    -44 F
STANLEY 1 SE RWIS         CHIPPEWA          403 AM    -43 F
LOYAL SCHOOL AWS          CLARK            1229 AM    -43 F
VOLK FIELD                JUNEAU            130 AM    -41 F
NECEDAH RAWS              JUNEAU            248 AM    -39 F
ALMA AWS                  BUFFALO           944 PM    -39 F
ARCADIA HILL RWIS         TREMPEALEAU       710 AM    -38 F
BUFFALO LUTHERAN AWS      BUFFALO           244 AM    -38 F
RICHLAND CENTER AWS       RICHLAND          314 AM    -38 F
FENNIMORE ELEMENTARY AWS  GRANT             129 AM    -37 F
MOUNT STERLING 1S RWIS    CRAWFORD          208 AM    -37 F
TOMAH 4N RWIS             MONROE           1107 PM    -35 F
LA CROSSE ASOS            LA CROSSE        1253 AM    -35 F
RIVERDALE SCHOOL AWS      GRANT            1214 AM    -35 F
PRAIRIE DU CHIEN AWOS     CRAWFORD         1235 AM    -35 F
PRAIRIE DU CHIEN AWS      CRAWFORD          814 PM    -33 F
SPARTA AWOS               MONROE            135 AM    -33 F
MAUSTON APRS              JUNEAU            232 AM    -30 F
LA CROSSE 1S GUND LUTH    LA CROSSE         146 AM    -30 F
BOSCOBEL ASOS             GRANT            1253 AM    -29 F
DICKEYVILLE RWIS          GRANT            1103 PM    -28 F
1 SE DOWNTOWN ONALASKA    LA CROSSE         342 AM    -28 F

KEY TO OBSERVATION TYPES
AWS - SENSORS FROM AWS INCORPORATED. OFTEN LOCATED AT SCHOOLS.
RWIS - ROAD WEATHER INFORMATION SYSTEMS. LOCATED ON MAJOR ROADS AND BRIDGES.
RAWS - FIRE WEATHER OBSERVATIONS. OFTEN LOCATED IN FORESTS.
ASOS/AWOS - AVIATION WEATHER OBSERVATIONS. LOCATED AT AIRPORTS.

OBSERVATIONS ARE COLLECTED FROM A VARIETY OF SOURCES WITH VARYING EQUIPMENT
AND EXPOSURE.  NOT ALL DATA LISTED IS CONSIDERED OFFICIAL.

Snowfall

Moderate to heavy snow developed behind the arctic cold front across southeast Minnesota and west central and north central Wisconsin on the morning of January 29th and continued into the afternoon.  Snow rates up to an inch per hour were reported at times.  Between 2 and 5 inches of snow fell northeast of a Grand Meadow, MN to Neillsville, WI line.  This snow, combined with strong winds resulted in blizzard conditions developing across much of southeast Minnesota and Buffalo County in west central Wisconsin.  Another band of snow move across the area from the mid afternoon through the evening of January 29th, which produced amounts generally less than an inch across northeast Iowa and the remainder of western Wisconsin.  The map below illustrates how much snow fell across the region.