The quality controlled Iowa COOP data for November 2017 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 36.1° or 0.5° below normal while precipitation totaled 0.44 inches or 1.61 inches less than normal.   This ranks as the 68th warmest and 15th driest November among 145 years of records.   A lower precipitation total has not been recorded for any month of the year since November 2007.

Temperatures. The first one-half of November was unusually cold and cloudy with the highest temperature during this period being only 57° at Keokuk on the 15th.   Afternoon high temperatures reached only 23° at Estherville and Spirit Lake on the 9th while the morning low fell to 6° at Swea City on the 10th, this being the lowest temperature recorded in Iowa for so early in the season since 2003.   Sidney finally brought Iowa’s first 60 degree temperature of the month on the 17th.   However, temperatures again fell to 6° on the morning of the 22nd at Estherville and Little Sioux.   Finally, the remainder of the month was unseasonably mild.   Sioux City set a daily record high temperature on the 23rd of 63° while nearly all of the state set records on the 24th with Iowa City Airport the hot spot at 74°.

Heating Degree Day Totals. Home heating requirements, as estimated by heating degree day totals, averaged 1% more than normal and 44% more than seen during the exceptionally mild November of 2016.   Heating degree totals thus far this heating season are running 10% less than normal, but 36% more than at this time last year when Iowa recorded its warmest fall since 1931.

Precipitation. The dry weather pattern that began in mid-October persisted through all of November.   Lost Nation in Clinton County recorded the most precipitation with 1.51 inches, but was still nearly an inch below normal.   Rock Rapids and Hawarden reported the least precipitation with only 0.02 inches.   At Rock Rapids this was the lowest November precipitation total since 1939.     Most of the month’s precipitation fell on the 11th-12th when up to 0.65 inches fell at Muscatine and on the 17th-18th when Keokuk picked up the most rain with 0.83 inches.   The dry weather was great for finishing up the fall harvest.   However, combined with a very dry growing season across southeastern portions of the state, this resulted in subsoil moisture levels being rated 72% short to very short in the south central district with 61% in the same categories across the southeast district according to the final USDA/NASS crop report of the season as of November 26.   Lower season-ending soil moisture levels were last recorded in 2013.   There were three dates (1st, 7th and 12th) when light snow briefly accumulated over very small areas of the state.   Maquoketa and Lowden reported the greatest accumulation with just 0.3 inches.   The statewide average snowfall was a trace, tying with seven other years for the lowest November snowfall total (the others were in 1912, 1914, 1939, 1960, 1963, 2009 and 2012) among 131 years of records.

Fall Summary. Temperatures over the three autumn months averaged 52.0° or 1.8° above normal while precipitation totaled 8.13 inches or 0.10 inches above normal.   This ranks as the 24th warmest and 58th wettest fall among 145 years of records.

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

                 _____2017_______________________________________
                 NOV  OCT  SEP  AUG  JUL  JUN  MAY  APR  MAR  FEB
Maximum High:     84    1  360    0    1   28   36    5   92  546
Minimum High:      9   96   15   41    0    8  189  122   22    0
Maximum Low:       3    2  129    0   12   95   13   43   43  154
Minimum Low:       5    4    3   23    1   59    5   12   42    0
Maximum Precip:    0  150   27   47   38   35   39   97   40   55

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

                      2017                                   
                 NOV   OCT   SEP   AUG   JUL   JUN   MAY   APR   MAR
High Temp Bias  -0.9  -0.4  -0.2  -0.4  -0.2   0.1  -0.2  -0.3  -1.0
High Temp STD    M     M     M     M     M     M     M     M     M
Low  Temp Bias  -0.2   0.1   0.2  -0.3  -0.3   0.1  -0.2  -0.3  -0.4 
Low  Temp STD    M     M     M     M     M     M     M     M     M
Precip    Bias  -0.13  0.09 -0.05 -0.05  0.14  0.08  0.07  0.02  0.05
Precip    STD    0.21  0.64  0.64  0.70  0.75  0.66  0.42  0.49  0.39

The standard deviations are missing this month due to some new code that is not behaving as I expected. Just haven't allocated time to figure out why yet, sorry.