2011-12 Meteorological Winter Summary

The 2011-12 meteorological winter was exceptionally warm across the Upper Mississippi River Valley.  Temperatures averaged 5 to 8 degrees above normal which made it the warmest winter since 2001-02. Rochester MN tied 2001-02 for their second warmest winter and La Crosse WI had their sixth warmest winter.

The following weather conditions led to this exceptionally warm start:

  1. Lack of Snow - This usually results in temperatures averaging about 11 degrees warmer than normal.
  2. Polar Jet Stream remained generally north of the area - This was a result of the Arctic Oscillation being in its positive phase for much of the winter.  When this occurs, the polar jet stream usually remains north of 60 degrees latitude.  This keeps the arctic air bottled up near the Arctic Circle.
  3. Madden Julian Oscillation (MJO) remained over the tropical Indian Ocean and Western Pacific Ocean - The Madden Julian Oscillation is a tropical disturbance that propagates eastward around the global tropics.  It typically originates over the Indian Ocean and then propagates around the world anywhere from 30 to 60 days.  When this oscillation is located across the Indian Ocean and Western Pacific, temperatures across the eastern half of the United States usually averages above normal. 

Here are more details on the winter for La Crosse WI and Rochester MN...

La Crosse, WI...

During meteorological winter (December 1 through February 29), La Crosse Municipal Airport had their sixth warmest winter.  The winter slightly wetter than normal and snowfall was below normal.  The information below provides more details on these statistics.

Temperatures - 6th Warmest

From December 1st through February 29th, the average temperature at La Crosse Municipal Airport was 27.0 degrees.  This was 6.5 degrees warmer than the 1981-2010 average of 20.5 degrees.  This was the sixth warmest winter and the warmest since 2001-02.  The table below lists the ten warmest winters in La Crosse.

         Warmest Meteorological Winters
                in La Crosse WI
                   1872-2012

                    Average
      Rank        Temperature       Winter
      ----        -----------       ------
        1         34.2 degrees    1877-1878
        2         29.6 degrees    1881-1882
        3         29.2 degrees    2001-2002
        4         28.8 degrees    1997-1998
        5         27.6 degrees    1930-1931
        6         27.0 degrees    2011-2012
        7         26.5 degrees    1931-1932
        8         26.1 degrees    1943-1944
        9         26.0 degrees    1918-1919
       10         25.9 degrees    1991-1992


The average maximum temperature was 34.9 degrees.  This was 5.4 degrees warmer than the 1981-2010 average of 28.7 degrees. The average minimum temperature was 19.0 degrees.  This was 6.8 degrees warmer than the 1981-2010 average of 12.2 degrees.  The table below contains the monthly temperatures and their departures from normal for the winter of 2011-12.

          Winter 2011-12 Temperatures
               in La Crosse WI

                  Average            Departure
   Month        Temperature         from Normal
   -----        -----------         -----------
 December       28.1 degrees        +6.5 degrees

 January        23.8 degrees        +6.4 degrees
 February       29.1 degrees        +6.6 degrees
 
 Winter         27.0 degrees        +6.5 degrees - 6th Warmest


The warmest temperature was 53 degrees on January 5th and January 10th.  The coldest temperature was -11 degrees on January 21st.

The daily average temperatures were above normal on 72 days (79.1 percent), below normal on 18 days (19.8 percent), and normal on 1 day (1.1 percent).

Precipitation  

From December 1st through February 29th, La Crosse Municipal Airport received 3.93 inches of precipitation.  This was four tenths of an inch above the winter normal of 3.53 inches.  The table below contains the monthly precipitation totals and their departures from normal for the winter of 2011-12.

          Winter 2011-12 Precipitation
               in La Crosse WI

                Precipitation         Departure
   Month            Total            from Normal
   -----        ------------         -----------
 December        1.41 inches        +0.05 inches
 January         1.08 inches        -0.04 inches
 February        1.44 inches        +0.39 inches
 
 Winter          3.93 inches        +0.40 inches


Two-thirds of the winter precipitation fell on just 4 days.  The wettest day was on December 3rd when 0.70 inches of precipitation fell.  Measurable precipitation fell on 27 days (29.7 percent) and a trace of precipitation fell on another 16 days (17.6 percent).

Snowfall

From December 1st through February 29th, the snow observer near La Crosse Municipal Airport received 20.3 inches of snow.  This was 9.9 inches below the normal of 30.2 inches.  The table below contains the monthly snowfall totals and their departures from normal for the winter of 2010-11.

           Winter 2011-12 Snowfall
               in La Crosse WI

                  Snowfall            Departure
   Month            Total            from Normal
   -----        ------------         -----------
 December         4.3 inches         -7.0 inches
 January         13.2 inches         +2.5 inches
 February         2.8 inches         -5.4 inches
 
 Winter          20.3 inches         -9.9 inches


Snow fell on 36 days (34.6 percent).  Measurable snow fell on 18 days (19.8 percent) and a trace of snow fell on another 18 days (19.8 percent).  The snowiest day was 5.4 inches on January 12th.

Snow Depth

From December 1st through February 29th, the official snow observer near La Crosse Municipal Airport had an average snow depth of 2.0 inches. This was 2.2 inches less than the average of 4.4 inches. This was the lowest average snow depth since the winter of 2002-03 (1.7 inches).

The greatest snow depth was 7 inches on January 21st, January 22nd, January 24th, and January 25th.

There was snow on the ground on 60 of 91 days (65.9 percent) this winter.  Measurable snow was on the ground on 50 days (54.9 percent) and trace amounts of snow were on the ground another 10 days (10.9 percent). 

Rochester, MN...

During meteorological winter (December 1 through February 29), Rochester tied 2001-02 for the second warmest winter.  Precipitation was slightly wetter than normal and snowfall was below normal.  The information below provides more details on these statistics.

Temperatures...Tied for 2nd Warmest

From December 1st through February 29th, Rochester International Airport had an average temperature of 25.5 degrees.  This was 7.0 degrees warmer than the 1981-2010 normal of 18.5 degrees. This tied the winter of 2001-02 for the second warmest winter.  The table below lists the ten warmest winters in Rochester MN.

         Warmest Meteorological Winters
                in Rochester MN
                   1886-2012

                    Average
      Rank        Temperature       Winter
      ----        -----------       ------
        1         26.0 degrees    1930-1931
        2         25.5 degrees    2011-2012
                  25.5 degrees    2001-2002
        4         24.5 degrees    1997-1998
        5         23.5 degrees    1986-1987
        6         23.3 degrees    1918-1919
        7         23.1 degrees    1991-1992
                  23.1 degrees    1931-1932
        9         22.6 degrees    1959-1960
       10         22.5 degrees    1982-1983


The average maximum temperature was 33.4 degrees.  This was 7.2 degrees warmer than the 1981-2010 average of 26.2 degrees. The average minimum temperature was 17.5 degrees.  This was 6.7 degrees warmer than the 1981-2010 average of 10.8 degrees.

The table below contains the monthly temperatures and their departures from normal for the winter of 2011-12.

          Winter 2011-12 Temperatures
               in Rochester MN

                  Average            Departure
   Month        Temperature         from Normal
   -----        -----------         -----------
 December       26.1 degrees        +6.4 degrees - 9th Warmest
 January        22.8 degrees        +7.1 degrees - 7th Warmest
 February       27.7 degrees        +7.4 degrees - 7th Warmest
 
 Winter         25.5 degrees        +7.0 degrees - 2nd Warmest


The warmest temperature was 53 degrees on January 5th. The coldest temperature was -11 degrees on January 21st.

The daily average temperatures were above normal on 72 days (79.1 percent), below normal on 18 days (19.8 percent), and normal on 1 day (1.1 percent).

Precipitation

From December 1st through February 29th, Rochester International Airport received 3.41 inches of precipitation.  This was nearly a half inch (0.49 inches) above the seasonal normal of 2.92 inches.  The table below contains the monthly precipitation totals and their departures from normal for the winter of 2011-12.

          Winter 2011-12 Precipitation
               in Rochester MN

                Precipitation         Departure
   Month            Total            from Normal
   -----        ------------         -----------
 December        1.21 inches        -0.02 inches
 January         0.57 inches        -0.29 inches
 February        1.63 inches        +0.80 inches
 
 Winter          3.41 inches        +0.49 inches


Nearly forty percent (39.3 percent) of the winter precipitation fell on the last two days of the winter.  This was enough to push the seasonal precipitation from below normal to above normal. The wettest day was on February 28th when 0.83 inches of precipitation fell.  Measurable precipitation fell on 26 days (28.6 percent) and a trace of precipitation fell on another 18 days (19.8 percent).

Snowfall

From December 1st through February 29th, the snow observer near Rochester International Airport received 20.5 inches of snow.  This was 12.5 inches below the normal of 33.0 inches.  This was the least snow total since the winter of 2005-06 (21.1 inches).  The table below contains the monthly snowfall totals and their departures from normal for the winter of 2011-12.

           Winter 2011-12 Snowfall
               in Rochester MN

                  Snowfall            Departure
   Month            Total            from Normal
   -----        ------------         -----------
 December         8.4 inches         -4.1 inches 
 January          8.1 inches         -3.9 inches
 February         4.0 inches         -4.5 inches
 
 Winter          20.5 inches        -12.5 inches


Snow Depth

From December 1st through February 29th, the official snow observer near Rochester International Airport had an average snow depth of 1.1 inches.  This was 4.3 inches less than the average of 5.4 inches. This was the lowest average snow depth since the winter of 2002-03 (1.1 inches) and this tied the winters of 1943-44, 1959-60, and 2002-03 for fifth lowest average winter snow depth.  The lowest average snow depth was 0.9 inches during the winters of 1967-68 and 1994-95.

The greatest snow depth for the winter was 5 inches from January 23rd through January 26th.



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