State climatologist calls 2008 weather wet, wild
Harry Hillaker, the State Climatologist with the Iowa Department of Agriculture and Land Stewardship, has released a summary of the weather in 2008. According to Hillaker, 2008 was the fourth wettest year in the 136 years that records exist. (Totals are only through Dec. 29 with preliminary data for the final four months of the year).
Statewide average temperature: 45.8 degrees or 2.0 degrees below normal. This ranks as the 12th coldest year among 136 years of state records and the coldest year since 1996. This ranking could change substantially when complete final data are available (anywhere from 8th to 18th). Only September and November recorded warmer than normal temperatures during the year.
Statewide average precipitation: 43.61 inches or 9.53 inches above normal. This ranks fourth highest among 136 years of records (only 1993, 1881 and 1902 saw more precipitation).
Statewide average snowfall: 48.9 inches or 16.5 inches above normal. This ranks as the seventh highest calendar year snowfall total among 121 years of record. The snowfall ranking could change to anywhere from second to seventh snowiest when complete final data become available. 1983 is the record year for snowfall with 51.0 inches.
Highest Temperature: 100 degrees at Hawarden on Aug. 3.
Lowest Temperature: -30 degrees at Stanley on January 24.
Tornadoes: The National Weather Service reports a preliminary total of 105 tornados in Iowa in 2008. This ties with 2001 as the second greatest annual tornado total (120 in 2004 is the record). The average annual number of confirmed tornadoes since 1995 in Iowa is 56.
Hillaker’s report also included his “Top Weather Stories of 2008” (chronological):
Mid-Winter Cold – Jan. 17 to Feb. 23. The coldest part of the 2007-2008 winter came between mid-January and late February (overall winter ranked 21st coldest among 136 years of records). Actual temperatures bottomed out at -30F at Stanley on the morning of Jan. 24 (lowest official reading in Iowa since -34 at Elkader on Dec. 25, 2000). The lowest Wind Chill Index (WCI) was -45F at Spencer and Estherville on the morning of Feb. 10 (lowest WCI since 1/10/1997). (Note: the Feb. 10, 2008 WCI would have been -69F on the old WCI in use prior to 2001).
Heavy snow – Feb. 2-28. Iowa recorded a statewide average of 15.8 inches of snow during February 2008. This ties for the third highest February total among 121 years of data and 14th highest for any calendar month. Oskaloosa recorded 41.7 inches of snow for the month thanks largely to two big events (11 inches on Feb. 3 and 15 inches on Feb. 6-8). Seasonal snow totals reached record highs at several southern and eastern Iowa locations. Dubuque Lock & Dam reported the most snow for the winter season with 87.6 inches. Seasonal snowfall was actually below normal over parts of west central Iowa. The statewide average seasonal snowfall was 45.1 inches, 12.7 inches above normal, and ranks 10th highest of record (highest since 2000-2001).
Dry Early Spring – Feb. 29 to March 30. Thankfully a period of drier than normal weather prevailed from Feb. 29 through March 30 across Iowa. There were also no rapid warm-ups, thus the deep moisture-rich snow pack that accumulated across Iowa over the winter melted fairly slowly and without substantial added rainfall. Nevertheless significant snow-melt flooding still occurred in parts of the state.
Very Wet Mid Spring – March 31 to May 11. The brief break in the wet weather pattern ended March 31. Rainfall was frequent and plentiful through May 11. The statewide average April precipitation was the second highest for the month among 136 years of records (behind 1999). Several cities set April rainfall records including Fayette where 11.98 inches exceeded their previous April record of 8.02 inches set in 1909 among 119 years of record.
Dry Mid-May – May 11-22. A much needed break in the cool and wet spring season came in mid May when a statewide average of only 0.08 inches of rain fell from May 11 to May 22. This break allowed farmers to get much of their 2008 planting completed before very heavy rains returned.
Parkersburg tornado – May 25. What had been a slow start to the Iowa severe weather season came to an abrupt and devastating end on the afternoon of May 25 when Iowa’s first F5 tornado since 1968 swept through Parkersburg and adjacent areas causing eight fatalities and an estimated $100 million in damage.
Major Floods – late May to mid June. An exceptionally wet 15 day period from May 29 to June 12 brought a statewide average of 9.03 inches of rain (normal 2.45 inches for the period). This was probably the wettest 15 days in state history and followed six months of unusually cold weather and an extended period of excessive precipitation dating back to August 2007. Record flooding resulted over much of eastern Iowa. Cedar Rapids was hardest hit with a June 13 crest on the Cedar River rising more than 11-feet higher than the previous record. Statewide flood damage has been estimated to be in the range of $10 billion in 2008. The first one-half of 2008 was the wettest January to June period on record in Iowa and followed the second wettest August to December period on record in 2007. June 2008 ranked second wettest June among 136 years of state records (behind June 1947).
Little Sioux tornado – June 11. An F3 tornado struck the Little Sioux Scout Ranch in west central Iowa on the evening of June 11 killing four Boy Scouts. This was one of 48 tornadoes recorded in Iowa during the month and pushed the statewide tornado fatality toll to its highest annual level since 1968. Severe storms were reported from all of Iowa’s 99 counties during June with the exception of Audubon County.
Heavy Rain in July, but more isolated in extent. Rainfall amounts returned to more seasonable levels in July with the exception of south central Iowa where torrential rains on the 17th, 24th and 28th brought major flooding, but on a much more limited geographic scale than seen earlier in the summer.
A Dry August. Nearly all of Iowa enjoyed a drier than normal August. However, parts of western and northern Iowa were in need of rainfall with Creston recording a record dry August (only 0.36 inches, previous record 0.46” in 1984 among 107 years or record).
Just a Little Summer Heat – Aug. 3-4. Hawarden recorded the only official 100F reading of the year on Aug. 3, while the heat index reached 112F on Aug. 4 at Burlington. Overall, there were very few hot days in 2008. Many locations across northeastern Iowa never reached 90 degrees during the year. While summertime temperatures averaged only 42nd lowest among 136 years of records there were few extremes of heat. Statewide there was an average of only five days with temperatures reaching 90 degrees. Only 1915 and 1992 saw fewer hot days than in 2008.
First Fall Freeze Comes Late – Sept. 15 to Oct. 28. Sibley recorded the first 32F reading of the fall on the morning of Sept. 15. A few northeastern Iowa locations recorded a hard freeze on Oct. 4-18; however, most of northern and western Iowa avoided a killing freeze until the unusually late date of Oct. 21 while southeastern Iowa did not have a hard freeze until Oct. 28. This late end to the growing season was extremely welcome as crops were late to mature owing to delayed planting and/or excessive wetness. Growing season temperatures averaged very close to normal from June through October, unlike in the 1993 flood year when very cool weather persisted through the entire growing season and greatly reduced crop yields.
Very Mild Early November – Nov. 1-5. Temperatures soared far above normal for the first five days of November with much of the state reaching the 70’s from Nov. 2-5. Sioux City recorded the highest temperature with 80F on Nov. 3.
Cold Late Year – Nov. 7 to Dec. 25. Temperatures averaged below normal on 35 days out of this 49 day period. Spencer Airport recorded the first subzero reading of the fall on Nov. 21. Cresco recorded the lowest temperature with -22F on Dec. 22. Estherville and Iowa Falls reported the lowest wind chill indices with -39F readings on the morning of Dec. 21.
Very Snowy Late Year – Nov. 29 to Dec. 27. The 2008-2009 snowfall season got off to a fairly slow start in October and November but made up for lost time beginning in late November. The first widespread snow event of the season arrived on Nov. 29-30 at the end of the Thanksgiving holiday weekend. Light to moderate snowfall events crossed the state an average of every other day from Dec. 3-25. The largest of these events came on December 18-19 when six to 12-inches of snow fell across much of northern Iowa while freezing rain and sleet fell over southern Iowa. The preliminary December statewide snowfall averaged 16.0 inches through the 30th. This ranks fourth highest snowfall for December among 122 years of snow records. December snow has been especially heavy across the northeastern Iowa where Decorah reported 35.2 inches of snow. Meanwhile, parts of southwest Iowa saw less snow than usual with only 3.5 inches at Glenwood.
