The quality controlled Iowa COOP data for February 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. Temperatures averaged 33.8° or 9.8° above normal while precipitation averaged 1.01 inches or just 0.04 inches less than normal. This ranks as the 3rd warmest and 72nd wettest February among 145 years of records. Only 1954 and 1998 brought a warmer February than this year.
Temperatures. Temperatures averaged near seasonal norms for the first nine days of the month. However, warmer than normal weather prevailed for all but one (25th) of the remaining days of February with an exceptionally mild period from the 16th through the 22nd when temperatures averaged 23.7° above normal. A look at the Iowa record books back to 1891 found 62 February dates when temperatures reached 70 degrees or higher somewhere in the state. Prior to this year no single February brought more than four days of 70 degree weather (1930, 1981 and 1996) with the longest streak of 70° weather being three consecutive days in 1996 (24th-25th-26th). However, this February brought eight days of 70° weather with seven of those coming consecutively from the 16th through the 22nd with one more on the last day of the month. Ottumwa recorded the highest temperature of the month with a 79° reading on the 22nd. This reading has been exceeded only three times previously in February in Iowa (82° at Sidney on 2/29/1972 and 80° at Clarinda and Mount Ayr on 2/24/1930). Daily record high temperatures were recorded somewhere in the state every day from the 16th through the 22nd, primarily across the southeast one-half of the state, with Ottumwa setting or tying daily records on each of these seven days. On the other extreme Little Sioux recorded the only subzero temperature of the month with a -3° reading on the morning of the 9th.
Heating Degree Day Totals. Home heating requirements, as estimated by heating degree day totals, averaged 25% less than normal and 19% less than last February. Heating degree day totals thus far this winter season are running 17% less than normal and 5% less than last season through the end of February. A warmer heating season was last recorded in the winter of 2001-2002.
Precipitation. There were only two measureable snow events during the month. The first one on the 8th brought snow to about the southern two-thirds of the state with greatest amounts falling across west central and south central Iowa where Indianola picked up 6.1 inches. The second, and much more intense event, brought snow to all of the state on the 23th-24th. Heaviest snow fell across the northwest where 12.5 inches fell near West Bend and 12.0 inches at Algona. An inch or less of snow fell across east central Iowa and the southern one-quarter of the state. Wind gusts up to 48 mph brought blizzard conditions across about the northwest one-third of the state with this late month storm. Monthly snow totals varied from only 0.3 inches at Manchester to 13.6 inches at Little Sioux. A statewide average of 4.5 inches of snow fell during the month, 2.3 inches less than normal and the lowest February total since 2009. This ranks as the 43rd lowest February snow total among 130 years of records. There were also several rain events during the month with the largest coming on the 20th when rain fell statewide with totals of an inch or more falling over parts of north central and northeast Iowa. Monthly precipitation totals varied from only 0.20 inches at Allerton where this was the driest February since 1970 to 2.78 inches at Nashua or more than 2.5 times their normal amount for February.
Severe Weather. Thunderstorms developed across eastern Iowa during the late afternoon of the 28th and brought one brief tornado in Clinton County and large hail reports from eleven east central and southeast Iowa counties. Only two other February tornadoes have been recorded in Iowa (Feb. 1, 1922 at Monticello and Feb. 23, 1977 at Mason City). Thunderstorms were also fairly widespread on the 6th-7th, 20th and 23rd-24th but with only a few very isolated large hail occurrences on the 7th and 20th.
Winter Summary. Temperatures over the three mid-winters months averaged 26.8° or 4.7° above normal while precipitation totaled 4.17 inches or 0.83 inches above normal. This ranks as the 9th warmest and 31st wettest winter among 144 years of records. Six of the top ten warmest winters have come within the past 20 years.
The following is the number of new daily records set at COOP sites based on data back to 1951.
2017____________2016____________________________ FEB JAN DEC NOV OCT SEP AUG JUL JUN MAY Maximum High: 546 43 40 226 242 225 32 17 238 65 Minimum High: 0 36 44 21 8 15 53 224 17 81 Maximum Low: 154 367 70 125 184 338 83 131 196 21 Minimum Low: 0 23 99 15 6 4 14 82 42 72 Maximum Precip: 55 219 167 85 118 295 196 151 84 92
The following is a table summarizing how well the IEM daily data estimator is working in comparison to the quality controlled data.
2017 2016 FEB JAN DEC NOV OCT SEP AUG JUL JUN High Temp Bias -0.9 0.2 0.3 0.2 0.1 0.1 0.1 0.1 0.2 High Temp STD M 2.0 2.0 2.1 2.2 2.0 1.8 1.9 2.1 Low Temp Bias -0.2 0.0 0.1 0.0 0.2 0.1 0.1 0.2 0.2 Low Temp STD M 2.3 2.3 2.8 2.5 2.3 2.0 2.0 2.3 Precip Bias 0.05 0.01 -0.02 0.00 0.00 -0.01 -0.01 -0.02 -0.02 Precip STD 0.33 0.07 0.07 0.09 0.12 0.27 0.30 0.29 0.25
The standard deviations are missing this month due to some new code that is not behaving as I expected. Will resolve prior to next month.