News and Notes

The quality controlled Iowa COOP data for November 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. Iowa temperatures averaged 29.1° or 7.5° below normal while precipitation averaged 0.82 inches or 1.23 inches below normal.   This ranks as the 4th coldest and 33rd driest November among 142 years of records.   A colder November was last recorded in 1991 and a drier one in 2007.

Temperatures. Unseasonably cold weather was persistent during the month with below normal temperatures prevailing for 21 days in November.   Temperatures failed to climb above freezing anywhere in the state between 9 a.m. November 11 and 1 a.m. November 19.   At Des Moines a streak of 252 consecutive hours below freezing began at midnight on the night of the 10th.   This streak was 48 hours longer than recorded in any other November among 137 years of records.   The season’s first subzero temperature was recorded at Little Sioux with a -2° reading on the morning of the 14th.   There were another six days in the month with temperatures falling to zero or below.   Swea City reported the lowest temperature with a -16° reading on the morning of the 27th.   However, despite the prevalence of unusually cold weather there were some brief, but sizable, warms spells.   Keosauqua reported the highest temperature of the month with a 72° maximum on the 10th where temperatures fell fifty degrees by the next morning.   A late month warm spell on the 29th pushed temperatures up to 66° at Glenwood, Lamoni and Castana and melted most of the state’s snow cover.

Heating Degree Day Totals. Home heating requirements, as estimated by heating degree day totals, averaged 25% greater than normal and 14% greater than last November.   Heating degree day totals so far this heating season (since July 1) are running 13% greater than normal and 10% greater than last year at this time.

Precipitation. The relatively dry weather pattern that began in mid-October continued through November.   November’s monthly precipitation totals varied from only 0.17 inches at Battle Creek (Ida County) to 2.43 inches at Brighton (Washington County).   Brighton was the only location in Iowa to report above normal precipitation during the month.   The season’s first accumulating snow arrived on the night of the 10th and brought one-half to two inches of snow to the northwest one-half of the state.   The month’s largest snow event brought snow statewide on the 15th-16th with amounts up to 5.5 inches at Ringsted (Emmet County).   The month’s largest precipitation event began with rain statewide on the 23rd and transitioned to snow across the east by late that night.   Northwest Iowa received only very light precipitation while several locations in Clinton County picked up more than 1.7 inches of rain.   Finally, snow fell over much of Iowa on the 26th with 6.0 inches reported at Emmetsburg, Britt and Rose Hill while Brighton recorded 6.8 inches.   Monthly snow totals varied from one inch at Keokuk and Shenandoah to 11.4 inches at Emmetsburg.   The statewide average snowfall was 5.0 inches or 2.3 inches above normal.   This was the snowiest November since 1991 and ranks 21st most snow among the past 128 Novembers

Fall Summary. Temperatures over the three autumn months of September, October and November averaged 47.4° or 2.8° below normal while precipitation totaled 8.39 inches or 0.36 inches above normal.   This ranks as the 12th coldest and 49th wettest fall among 142 years of records.   This was the coolest fall since 1993 although this was nearly all a result of the unseasonably cold November.   This was also the wettest fall in five years with the first half of the season much wetter than the second half.

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

                 __________2014__________________________________
                 NOV  OCT  SEP  AUG  JUL  JUN  MAY  APR  MAR  FEB
Maximum High:     24   97   25   25    4   27   79  118   24   26
Minimum High:    634   89  267  161  399   37  235  174  406  306
Maximum Low:       5   56   86  113    8  122  102   40    7    7
Minimum Low:     550   22  180   33  330   58  171  209  439  379
Maximum Precip:   67  149  176  182  134  342   92  187   29   91

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_______________________________
                 NOV   OCT   SEP   AUG   JUL   JUN   MAY   APR
High Temp Bias   0.4   0.4   0.2   0.0   0.2   0.1   0.2   0.4
High Temp RMSE   0.8   0.8   0.8   0.7   0.8   0.7   0.8   0.8
Low  Temp Bias   0.1   0.2   0.2   0.1   0.2   0.1   0.1   0.2
Low  Temp RMSE   0.9   0.9   0.9   0.8   1.0   0.8   0.9   1.0
Precip    Bias   0.15  0.26  0.33  0.39  0.2   0.13  0.20  0.14
Precip    RMSE   0.25  0.51  0.75  1.11  0.92  1.39  0.64  0.63