April 2012 was Cooler than March 2012 (530 AM 5/1/12)

On the minds of many weather enthusiasts lately, was whether we would end up with a cooler average temperature for April 2012 compared to our "Hot" March 2012 average temperature.  Now that April is in the books, the answer to this is yes, April was cooler.  This is a feat that was accomplished in Milwaukee only one other time (1907) and was tied at Madison that same year (i.e. March and April had the same average temperature in 1907).  Madison had never had a cooler April than the preceding March until this year.   

 

 1907 Average Temperatures

2012 Average Temperatures

 ( °F )

March

April

 March

 April

 Milwaukee

38.5

37.2

 48.8

 46.3

 Madison

37.6

37.6

 50.1

 47.9


 For Milwaukee:

The average temperature for March 2012 was 48.8 °F which was 13.8 degrees above normal. The average in April was 46.3 °F ,  2.5 degrees cooler than March! Even so, April was near normal for Milwaukee, finishing 0.7 °F above the average temperature of 45.6 °F

 Temperature Graphs For March and April 2012 in Milwaukee

 March 2012

 April 2012

 

 

 

For Madison: 

The average temperature for March 2012 was 50.1 °F which was 16.1 degrees above normal. The average in April was 47.9 °F,  2.2 degrees cooler than March! April was also near normal for Madison, finishing 1.3 °F above the average temperature of 46.6 °F

 Temperature Graphs For March and April 2012 in Madison

 March 2012

 April 2012

 

 

Why such a big flip flop in temperatures?

The weather pattern in March was driven in large part by an upper level jet stream that was nearly stationary for an extended period of time to our west, then flowing well north into Canada.  The strength and persistence of that pattern was uncharacteristic for March.  High pressure dominated from the Great Lakes to the southeast U.S.   As a result, we stayed warm and mostly dry.  Low pressure held over the western United States, bringing the West Coast a very cool, wet and sometimes snowy March. (see image below)

The weather pattern in April shifted to a pattern more typical for Spring.  Low pressure was much more persistent to our north, with high pressure over the western U.S.  This put the upper level jet stream over or south of the Great Lakes, allowing cooler air from Canada to penetrate into the region.  (see image below)

So what does this mean for this summer?

At this point, we are unable to determine what we have in store for this summer. However, we can tell you what happened in the summer of 1907. Milwaukee and Madison were both cooler than normal for each summer month. See the table below for the breakdown of normal average summer temperatures, and the average temperatures that occurred in the summer of 1907.

  Milwaukee Normal Average Temps 1907 Milwaukee Average Temps Madison Normal Average Temps

1907 Madison Average Temps

June 66.6 63.3 67.3 64.6
July 72.1 70.1 71.6 70.9
August 71.0 67.0 69.5 67.4
Entire Summer 69.9 66.8 69.5 67.6

 

Steve Davis/Ed Townsend/J. J. Wood

National Weather Service Milwaukee/Sullivan, WI (MKX)



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