The quality controlled Iowa COOP data for April 2014 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. Temperatures averaged 47.2° or 1.7° below normal while precipitation totaled 4.83 inches or 1.32 inches above normal.   This ranks as the 43rd coolest and 12th wettest April among 142 years of records.   This was the seventh consecutive cooler than normal month and tenth consecutive wetter than normal April.

Temperatures. April temperatures were much closer to normal than recent months but cooler than typical weather was again predominant with below normal readings outnumbering above normal ones by 18 days to 12.   The year’s first 80 degree readings were recorded in a few western areas on the 9th with a maximum of 83° at Sioux City.   The month’s highest temperatures were recorded just a few days later with Clarinda, Des Moines and Indianola reaching 86° on the 12th.   On the other extreme Sanborn reported a minimum temperature of 11° on the morning of the 15th.   The last remnants of frozen soil finally thawed across northern Iowa about April 22.

Precipitation. Winter-like weather returned to the state after a mild last few days of March with accumulating snow falling across the northwest one-half of Iowa on the 3rd-4th.   Greatest snow totals were reported at Lake Park, Dickinson Co. (9.7 inches) and near Cleghorn, Cherokee Co. (9.0 inches).  For much of the far northwest corner of the state this snow storm was the largest precipitation event of the month and largest snow event of the winter.   Moderate to heavy precipitation covered all but far northwest Iowa from the 12th to the 14th.   Storm total rainfall exceeded four inches in a few areas from south central into northeast Iowa with 5.42 inches at Ladora (Iowa Co.) and 5.20 inches at Pella.   This was the state’s largest precipitation event since late May 2013.   The rain turned to snow over most of the state with light accumulations over the northwest one-half of Iowa.   Finally, a very slow moving storm brought substantial moisture to nearly all of Iowa from the 27th into May 1st.   Rain totals with this late month storm system reached 4.42 inches at Bondurant (Polk Co.) and 4.30 inches at Maxwell (Story Co.).   Snow also accumulated across parts of north central Iowa on the 29th-30th with 2.3 inches at Elma (Howard Co.) and 2.2 inches at Saint Ansgar (Mitchell Co.).   Monthly precipitation totals varied from 1.25 inches at Rock Rapids, their lowest April total since 1996, to 9.10 inches at Pella, their second largest April total among 87 years of record (10.04” in 1991).   The statewide average snowfall was 1.9 inches or 0.3 inches above normal to rank as the 37th snowiest April among 127 years of records.

Heating Degree Day Totals. Home heating requirements, as estimated by heating degree day totals, averaged 17% less than last April but 8% more than normal.   Degree day totals so far this heating season (since July 1, 2013) are running 11% greater than last season at this time and 14% greater than normal.

Severe Weather. There were two severe weather outbreaks during the month.   The most widespread event was on the 12th with large hail or high winds reported from 44 counties across the southeastern two-thirds of the state.   The second event brought high winds to 17 southeastern Iowa counties on the afternoon of the 27th.   This second event brought an EF1 tornado that tracked 46 miles across four counties from just north of Ottumwa to just west of Iowa City and resulted in two fatalities at separate locations in Keokuk County. Chariton.

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

                 2014_____________________2013___________________
                 APR  MAR  FEB  JAN  DEC  NOV  OCT  SEP  AUG  JUL
Maximum High:    118   24   26   79   21   18   31  364  160   13
Minimum High:    174  406  306  219  141  170   60    9  102  204
Maximum Low:      40    7    7   22   14   25   46  213  183   58
Minimum Low:     209  439  379  194  177  241   70   32   96  217
Maximum Precip:  187   29   91   36   41  123  138   82   44   51

The following is some bulk statistics on how well IEM's daily COOP data estimator is performing on a monthly basis versus this QC'd dataset.

                 2014________________________2013_____________
                 APR   MAR   FEB   JAN   DEC   NOV   OCT   SEP
High Temp Bias   0.4   1.3   1.4   0.8   0.7   1.1   0.2   0.2
High Temp RMSE   0.8   1.8   1.7   1.3   1.0   1.3   0.7   0.9
Low  Temp Bias   0.2   2.1   2.7   1.4   1.3   1.2   1.4   1.3
Low  Temp RMSE   1.0   2.4   2.9   1.6   1.6   1.5   1.7   1.8
Precip    Bias   0.14  0.36  0.31  0.49  0.24  0.09  0.18 -0.08
Precip    RMSE   0.63  0.46  0.56  0.59  0.31  0.28  0.59  0.46