Search Archive:
<< Previous      Next >>
1685 Views November COOP Data Uploaded


The quality controlled Iowa COOP data for November 2015 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 41.8° or 5.2° above normal while precipitation totaled 4.23 inches or 2.18 inches above normal.   This ranks as the 10th warmest and 7th wettest November among 143 years of Iowa records.   A warmer November was last recorded in 2009 and a wetter one in 1992.

Temperatures. Temperatures were above normal during all of the first 19 days of the month, averaging 8.5 degrees above normal for the period.   Much more seasonal temperatures prevailed for the remainder of the month with readings averaging 0.7 degrees below normal for the final 11 days of November.   Daytime highs reached into the mid-seventies somewhere in the state on each of the first five days of the month with Des Moines, Glenwood and Shenandoah recording the highest temperatures of the month with 79° readings on the 2nd.   At the Des Moines Airport the first freeze (32°) of the season was finally recorded on the morning of the 13th.   This was the latest ‘first’ freeze among 138 years of records at Des Moines (old record November 11, 1882).   However, the Des Moines Airport freeze date was not representative of the state as a whole as only two other official measurement points recorded their first freeze of the 2015 fall season in November (the others were NWS-Johnston on Nov. 7 and Keokuk Lock & Dam on Nov.9).   The statewide record for latest first freeze was set in Keokuk on November 24, 1944.   Very cold weather did arrive following the major snowstorm of the 20th with Spencer Airport recording a low of -4° on the morning of the 21st while Waterloo Airport and Stanley recorded lows of -5° on the night of the 21st.

Heating Degree Days. Home heating requirements, as estimated by heating degree day totals, averaged 35% less than last November (which was the 4th coldest November on record) and 19% less than normal.   Heating degree day totals so far this heating season are running 30% less than last year at this time and 21% less than normal.

Precipitation. November began with relatively dry weather until Veteran’s Day when the first of a parade of five storm systems brought widespread precipitation to Iowa.   The Veteran’s Day event saw thunderstorms develop statewide with unseasonably heavy rain over far northwest Iowa and high winds and tornadoes over southern Iowa.   The tail-end of this first storm system also brought the state’s first accumulating snow to portions of west central Iowa.   Additional storm systems came through at about four day intervals on the 16th-18th, 20th-21st, 25th-27th and 29th-30th.   The most widespread rain came with storm #2 on the 16th-18th with a statewide average of 1.31 inches of rain.   The third storm was noteworthy owing to the heavy snow that fell across much of the state.   More than ten inches of snow fell across a wide area of northern Iowa with 15 inches reported at Rock Rapids and 16 inches near Kesley.   This event brought Iowa’s most widespread heavy snowfall for so early in the winter season since November 17-18, 1957.   The fourth storm system brought light snow to northwest Iowa and 1.5 to 2.5 inches of rain to the southeast one-third of the state.   Finally, the last storm brought heavy snow to northwest Iowa with 10 inches reported at Everly and Lake Park and one-half to an inch of rain elsewhere.   Much of the snow on November 30 fell after the final measurements for the month (the daily measurements are made at 7 or 8 a.m. at most locations), thus will be included in the December totals.   Monthly precipitation totals were above normal at all reporting points and varied from 2.63 inches at Zearing to 7.56 inches at Eldridge.   Record maximum precipitation totals for November were set at several locations:

StationNov 2015Old November RecordPeriod of Record
Sanborn6.14 inches4.96 in 1991104 years
Primghar5.87 inches4.16 in 198383 years
Rock Rapids5.62 inches4.77 in 1975113 years
Storm Lake5.57 inches4.20 in 1983124 years
Spencer5.48 inches4.51 in 1896103 years
Sheldon5.37 inches5.05 in 1909104 years
Cherokee4.93 inches4.54 in 198394 years
Shenandoah4.62 inches4.49 in 198383 years
Sibley4.59 inches4.24 in 1905116 years
Sioux City4.55 inches4.41 in 1922134 years

Monthly snow totals varied from only trace amounts at several far southwest Iowa locations to 22.4 inches at Spencer.   The statewide average snowfall was 6.3 inches or 3.6 inches above normal.   This is the 13th highest November snow total among 129 years of record and the highest for the month since 1991.

Severe Weather. The National Weather Service reported a total of 19 tornadoes across southern Iowa on Veteran’s Day with damaging winds reported from 51 counties, mostly in central and southern Iowa.   The tornado total exceeds the previous November record of 12 set on November 12, 2005.

Fall Summary. Temperatures for the three fall months of September, October and November averaged 54.4° or 4.2° above normal while precipitation totaled 10.14 inches or 2.11 inches above normal.   This ranks as the 6th warmest and 22nd wettest fall among 143 years of records.   A warmer fall was last recorded in 1963 and a wetter one in 1992.

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

                 NOV  OCT  SEP  AUG  JUL  JUN  MAY  APR  MAR  FEB
Maximum High:     85   75  130   25   22   69   28   34  182   13
Minimum High:     56   21   13  269  261   88  316   28  102  364
Maximum Low:     171   79  336   38   54   32   82   34   29   25
Minimum Low:      58   20   25  156  139   26   87   76   98  345
Maximum Precip:  316  162  150  158  214  151  155  122   17  113

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

                 NOV   OCT   SEP   AUG   JUL   JUN   MAY   APR   MAR
High Temp Bias   0.3   0.2   0.0   0.1   0.0   0.0  -0.1   0.0   0.3
High Temp STD    2.2   1.8   1.7   1.8   1.7   1.7   2.5   2.2   2.6
Low  Temp Bias   0.2   0.1   0.0   0.2   0.2   0.2   0.1   0.3   0.4
Low  Temp STD    2.7   2.6   2.1   2.1   2.0   2.0   2.0   2.7   2.9
Precip    Bias  -0.00 -0.01  0.01 -0.01  0.00  0.00 -0.01  0.00  0.01
Precip    STD    0.14  0.08  0.26  0.27  0.29  0.33  0.20  0.13  0.13