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878 Views August COOP Data Uploaded


The quality controlled Iowa COOP data for August 2016 has been uploaded to the IEM. These observations are kindly provided by Harry Hillaker, our state climatologist, who passes along these notes on the month:

General Summary. August temperatures averaged 72.3° or 0.8° above normal while precipitation totaled 6.05 inches or 1.85 inches above normal.   This ranks as the 58th warmest and 14th wettest August among 144 years of records.   A warmer August was last recorded in 2010 and a wetter one in 2007.

Temperatures. August temperatures fluctuated rather regularly throughout the month with no extended periods of either unusually warm or cool weather.   The hottest weather came on the 4th, 10th and 11th when actual temperatures reached into the mid-nineties and heat indices reached 110° or higher somewhere in the state each day.   As is typical as the day length slowly shortens during the month the lowest temperatures came during the second one-half of August with morning lows dipping into the forties in some locations on the 21st, 22nd and 26th.   Overall temperature extremes varied from a high of 97° at Lamoni on the afternoon of the 11th to lows of 46° on the morning of the 21st at Battle Creek, Sheldon and the Spencer Airport.

Cooling Degree Days. Home air conditioning requirements, as estimated by cooling degree day totals, averaged 44% more than last August and 9% greater than normal.   Thus far this year air conditioning requirements are running 13% more than normal and 33% greater than last year at this time.

Precipitation. Rain was frequent throughout the month and greater than normal over most of Iowa.   Below normal rain totals were mostly confined to far northwest Iowa and small areas of the west central and south central portions of the state.   The most widespread rains of the month came on the 11th-12th when a statewide average of 2.21 inches fell.   Greatest rains with this event fell along of the U.S. Highway 30 corridor from Boone County eastward to Clinton and Scott Counties with Swisher in Johnson County reporting a storm total of 7.05 inches.   However, the worst flooding of the month came as a result of a prolonged period of heavy rain over the night of the 23rd across far northeastern Iowa where a location five miles southeast of Decorah reported a storm total of 8.46 inches.   Record flood crests were established along some reaches of the Upper Iowa and Turkey Rivers on the 24th.   Monthly rain totals varied from 1.73 inches at Rock Rapids to 13.84 inches at Decorah.  This was the second highest August total among 131 years of records at Decorah (15.11 in 2007).

Summer Summary. Temperatures over the three summer months averaged 72.8° or 1.2° above normal while precipitation totaled 15.63 inches or 1.92 inches above normal.   This ranks as the 50th warmest and 20th wettest summer among 144 years of records.   This was the hottest summer since 2012.   Despite the high precipitation ranking this summer’s total was less than recorded during the past two summers.

The following is the number of new daily records set at COOP sites based on data back to 1951.

                 AUG  JUL  JUN  MAY  APR  MAR  FEB  JAN  DEC  NOV
Maximum High:     32   17  238   65   84  135  213   29  244   85
Minimum High:     53  224   17   81   72    5   59   98   13   56
Maximum Low:      83  131  196   21   63  268  159   89  467  171
Minimum Low:      14   82   42   72   53   10   19   63    5   58
Maximum Precip:  196  151   84   92   72  124  141  156  439  316

The following is a table summarizing how well the IEM daily data estimator is working in comparison to the quality controlled data.

                      2016                                    2015
                 AUG   JUL   JUN   MAY   APR   MAR   FEB   JAN   DEC
High Temp Bias   0.1   0.1   0.2  -0.1   0.2   0.4   0.6   0.3   0.2
High Temp STD    1.8   1.9   2.1   2.0   2.5   2.6   2.4   2.1   2.0
Low  Temp Bias   0.1   0.2   0.2   0.2   0.2   0.3   0.2   0.2   0.1
Low  Temp STD    2.0   2.0   2.3   2.5   2.4   2.7   2.4   2.5   2.2
Precip    Bias  -0.01 -0.02 -0.02  0.00  0.00  0.00  0.01 -0.01 -0.01
Precip    STD    0.30  0.29  0.25  0.17  0.11  0.09  0.07  0.27  0.14