A Warmer And Wetter Autumn For La Crosse and Rochester

During meteorological Autumn (September 1 through November 30), both La Crosse Municipal and Rochester International airports were warmer and wetter than normal.  In addition, autumn snowfall was below normal at both locations.  Both the temperatures and snowfall were very typical of La Nina.  Meanwhile the above-normal precipitation is unusual for a La Nina, because they are typically dry.   In both locations, these precipitation values were greatly skewed upward by three to four abnormally wet storm systems.  These storm systems produced around three quarters of the precipitation in just 9 days.  The remainder of the autumn was mainly dry.

The information below provides more details on these statistics in La Crosse, WI and Rochester, MN.

La Crosse WI...

Temperatures...

From September 1 through November 30 2010...La Crosse Municipal Airport had an average temperature of 50.7 degrees.  This was 1.1 degrees above the 1971-2000 normal of 49.6 degrees.  The average high temperature was 60.8 degrees which was 1.3 degrees warmer than 1971-2000 normal of 59.5 degrees.  The average low temperature was 40.6 degrees which was 0.9 degrees warmer than 1971-2000 normal of 39.7 degrees.  The table below contains the monthly average temperatures and their departures from normal for the autumn of 2010.

           Autumn 2010 Temperatures
               in La Crosse WI

                  Average            Departure
   Month        Temperature         from Normal
   -----        -----------         -----------
   September   61.2 degrees        -1.5 degrees
   October     53.6 degrees        +3.0 degrees 
   November    37.2 degrees        +1.7 degrees 
 
   Autumn      50.7 degrees        +1.1 degrees


This autumn/s temperatures were very typical for a La Nina.  September temperatures averaged below normal /-1.5 degrees/.  This has occurred during thirteen of the nineteen /68.4 percent/ La Ninas since 1950.  Meanwhile temperatures averaged above normal during both October /+3.0 degrees/ and November /+1.7 degrees/.  During these two months...the average temperature has been warmer than normal during sixteen of the nineteen /84.2 percent/ La Ninas since 1950.

One of the warmest stretches of weather during the autumn occurred from October 8th through October 12th.  During this stretch of days...high temperatures were 80 degrees or higher.  This was the second longest stretch of 80-degree days during an October.  The record is seven days back in 1997 /October 2 through October 8th/.

Precipitation...

From September 1 through November 30 2010...La Crosse Municipal Airport received 11.04 inches of precipitation.  This was 3.38 inches above the 1971-2000 normal of 7.66 inches.  The table below contains the monthly precipitation totals and their departures from normal for the autumn of 2010.

          Autumn 2010 Precipitation
               in La Crosse WI

                Precipitation         Departure
   Month            Total            from Normal
   -----        ------------         -----------
   September    7.03 inches         +3.63 inches  - 13th Wettest
   October      2.08 inches         -0.08 inches  
   November     1.93 inches         -0.17 inches 
 
   Autumn      11.04 inches         +3.38 inches


Just over 70 percent /70.7 percent/ of the precipitation this autumn fell on just nine days /September 21-23 - 4.49 inches...October 23-26 - 2.08 inches...and November 12-13 - 1.23 inches/.  Above normal precipitation during La Nina autumns are somewhat unusual.  Only seven of the nineteen /36.8 percent/ La Ninas since 1950 experienced above-normal precipitation.

From September 24th through October 22nd...La Crosse Municipal Airport saw measurable rain /0.01 inches or greater/.  This 29-day stretch with no measurable rain was the sixth longest and the longest since a 30-day stretch back in 1980 /April 10th through May 9th/.  The longest stretch without measurable rain was 44 days back in 1979 /October 20th through December 2nd/.

Snowfall...

From September 1 through November 30 2010...La Crosse Municipal Airport received just a trace of snow.  This was 4.6 inches below the normal of 4.6 inches.  This tied 1904...1913...1941...1969...1973...1987...and 2001 for the least amount of snow during an autumn. The table below contains the monthly snowfall totals and their departures from normal for the autumn of 2010.

            Autumn 2010 Snowfall
               in La Crosse WI

                  Snowfall            Departure
   Month            Total            from Normal
   -----        ------------         -----------
   September     0.0 inches           0.0 inches
   October       0.0 inches          -0.2 inches  
   November        Trace             -4.4 inches   2nd Least
 
   Autumn          Trace             -4.4 inches   Least Snow


The below-normal autumn snowfall is very typical of a La Nina.  Fourteen out of the nineteen /73.7 percent/ La Ninas since 1950 have produced below normal autumn snowfall.

Rochester MN...

Temperatures...

From September 1 through November 30 2010...Rochester International Airport had an average temperature of 49.1 degrees.  This was 3.4 degrees above the normal of 45.7 degrees.  This tied 1934...1947...and 1958 for the seventeenth warmest autumn.  The table below contains the twenty warmest autumns.

               Warmest Autumns
               in Rochester MN
                  1886-2009

                  Average
    Rank        Temperature         Year
    ----        -----------         ----
      1         52.7 degrees        1963
      2         50.7 degrees        2007
                50.7 degrees        2005
      4         50.6 degrees        1953
      5         50.4 degrees        1914
      6         50.1 degrees        1998
      7         50.0 degrees        2001
                50.0 degrees        1994
                50.0 degrees        1971
     10         50.0 degrees        1948
     11         49.8 degrees        2004
     12         49.4 degrees        1941
                49.4 degrees        1913
     14         49.3 degrees        2009
                49.3 degrees        1973
                49.3 degrees        1944
     17         49.1 degrees        2010
                49.1 degrees        1958
                49.1 degrees        1947
                49.1 degrees        1934


The average high temperature during autumn of 2010 was 59.3 degrees which was 4.3 degrees warmer than 1971-2000 normal of 55.0 degrees.  The average low temperature was 38.9 degrees which was 2.4 degrees warmer than 1971-2000 normal of 36.5 degrees.  The table below contains the monthly average temperatures and their departures from normal for the autumn of 2010.

           Autumn 2010 Temperatures
               in Rochester MN

                  Average            Departure
   Month        Temperature         from Normal
   -----        -----------         -----------
   September   59.5 degrees        +0.6 degrees
   October     52.6 degrees        +5.6 degrees - 11th Warmest
   November    35.1 degrees        +3.9 degrees
 
   Autumn      49.1 degrees        +3.4 degrees - 17th Warmest


This autumn/s temperatures were very typical for a La Nina.  During the nineteen La Ninas since 1950...seventeen /89.5 percent/ of them have averaged above normal. 

One of the warmest stretches of weather during the autumn occurred from October 8th through October 11th.  During this stretch of days...high temperatures were 80 degrees or higher.  This along with a similar stretch back in 1947 /October 14-17/ was the longest stretch of 80 degree days in an October.  On October 9th...the high temperature at Rochester International Airport was 90 degrees.  This was the warmest temperature so late in the year.  The previous record was 88 degrees on October 8 1916.  This was also the latest 90 degree temperature recorded in a year.  The previous record was 93 degrees on October 3 1997.

Precipitation...

From September 1 through November 30 2010...Rochester International Airport received 13.60 inches of precipitation.  This was 6.27 inches above the normal 7.33 inches.  This was the second wettest autumn.  The only other autumn which was wetter was 1986 when 14.91 inches of precipitation fell.  The table below contains the ten wettest autumns in Rochester MN.

               Wettest Autumns
               in Rochester MN
                  1886-2009

                Precipitation
    Rank            Total          Year
    ----        ------------        ----
      1         14.91 inches        1986
      2         13.60 inches        2010
      3         13.48 inches        1911
      4         12.21 inches        1970
      5         11.81 inches        1973
      6         11.73 inches        1934
      7         11.64 inches        1972
      8         11.50 inches        1983
      9         11.33 inches        1931
     10         11.09 inches        1938


The table below contains the monthly precipitation totals and their departures from normal for the autumn of 2010.

          Autumn 2010 Precipitation
               in Rochester MN

                Precipitation         Departure
   Month            Total            from Normal
   -----        ------------         -----------
   September    9.95 inches         +6.83 inches - 2nd Wettest
   October      0.79 inches         -1.41 inches - 16th Driest
   November     2.86 inches         +0.51 inches
 
   Autumn      13.60 inches         +6.27 inches - 2nd wettest


Nearly 80 percent /77.8 percent/ of the precipitation this autumn fell on just six days /September 15 - 1.94 inches...September 21-23 - 6.48 inches...and November 12-13 - 2.16 inches/.  Above normal precipitation during La Nina autumns are somewhat unusual.  Only seven of the nineteen /36.8 percent/ La Ninas since 1950 experienced above-normal precipitation.

Snowfall...

From September 1 through November 30 2010...Rochester International Airport received 1.3 inches of snow.  This was 6.8 inches below the 1971-2000 normal of 8.1 inches.  The below-normal autumn snowfall is very typical of a La Nina.  Eighteen out of the nineteen /94.7 percent/ La Ninas since 1950 have produced below normal autumn snowfall.

The table below contains the monthly snowfall totals and their departures from normal for the autumn of 2010.

            Autumn 2010 Snowfall
               in Rochester MN

                  Snowfall            Departure
   Month            Total            from Normal
   -----        ------------         -----------
   September     0.0 inches           0.0 inches
   October       0.0 inches          -1.0 inches 
   November      1.3 inches          -5.8 inches 
 
   Autumn        1.3 inches          -6.8 inches



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