Month: May 2016

On This Day in Iowa Weather History – May 21, 2004 Tornado Outbreak

On May 21, 2004, a significant severe weather outbreak began that morning and continued across the state throughout the day/evening and lasted well into the following morning on the 22nd. There were 16 tornadoes that occurred across Iowa including one that injured 15 people in and around the small town of Bradgate, Iowa. The Bradgate tornado was rated an F2 (before the EF scale came into effect).  Another significant tornado just west of Bradgate was a F1 in Rolfe. One thing to note, the Bradgate tornado began just south of the town of Rolfe and in this location was rated F2 (See Survey Map). Below are several damage photos from the NWS survey team along with a few aerial shots courtesy of KCCI and John McLaughlin.  There is also a quick loop of the storm relative velocity data for the Bradgate tornado. In addition to the multitude of tornadoes, large hail was reported across the state including softball sized hail in Spencer.  In fact, there were two separate incidents where softball hail fell, first with a storm around 10 am and then again with another storm around 4 pm. Some of the storms also produced very heavy rainfall and flooding with accumulations of 4.75 inches at Emmetsburg, 5.14 inches at Decorah, and 6.10 inches at Mason City.

NWS Damage Survey from the May 21, 2004 Bradgate/Rolfe F2/F1 tornadoes respectively.

NWS Damage Survey from the May 21, 2004 Bradgate/Rolfe F2/F1 tornadoes respectively.

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Blog post by Kenny Podrazik – NWS Des Moines

 

On This Date in Iowa Weather History – May 6

Iowa certainly has had its extreme weather. May is no exception and today (May 6) has proven that Iowa can experience many different types of weather no matter the season. From snow to tornadoes to extreme heat or bitter cold and not to forget flooding. Below are 6 years of the most extreme weather across Iowa that has occurred on May 6.

  • 1885: A late spring cold spell produced frost and flurries across Iowa from May 6-9, 1885.  On the morning of the 6th it was reported that ice half an inch thick formed on standing water in Muscatine County. Flurries were reported at Sibley, St. Ansgar, and Waukon that morning and at other stations across northern Iowa on the following two days. The cold spell resulted in widespread damage to garden plants, orchards, and other vegetation across the state.
  • 1890: Unseasonably cold weather resulted in light snow mixed with rain and sleet in some areas. At Des Moines the Weather Bureau observer reported a trace of snow, while at Amana the observer wrote that ‘snow fell on the 6th, covering ground to a depth of one inch, but all melted by noon.’
  • 1934: One of the hottest summers on record in Iowa began in earnest as the temperature reached 100 F at Sioux City where this remains the earliest date of triple digit heat on record. This was only the first of a remarkable 11 days that month on which a 100 F or higher temperature was recorded somewhere in Iowa. Other reported high temperatures included 100 F at Alton, 99 F at Le Mars, Storm Lake, and Waterloo, 98 F at Algona and Grinnell, and 97 F at Atlantic, Fayette, and Washington. At Des Moines the month would finish as the warmest May on record with an average temperature of 71.1 F. A couple figures in the slideshow below shows the maximum temperatures and their departure from normal.
  • 1971: Severe weather struck southwestern Iowa for the second consecutive day. After an F3 tornado on the 5th injured 12 people in Taylor County as it passed through the town of Conway, a severe hail storm on the 6th dropped stones 2 inches in diameter in Mills County for such duration that they drifted 2 to 3 feet deep in the ditches and gullies around Glenwood.
  • 1983: A tornado touched down briefly in Pleasant Hill on the eastern edge of Des Moines, producing F2 damage as it destroyed 11 homes and damaged about two dozen more on a path only 8 to 10 blocks long and 50 to 75 yards wide. Several other tornadoes touched down across central and southwestern Iowa that evening but produced only minor damage with no injuries.
  • 1989: Unseasonably cold air settled across Iowa for the first week or two of May. The coldest temperatures were reached on the 6th when flurries were reported at most locations in the state and Hampton measured a tenth of an inch of snow. Temperatures bottomed out in the 20s at most stations north of I-80 and in the low to mid 30s to the south with the lowest readings including 26 F at Allison, Fayette, and Oelwein, 25 F at nine stations including Decorah, Forest City, and Hampton, 24 F at Charles City and Colo, and 23 F at Cresco. The low temperatures across Iowa were 12 to 18 degrees below normal! See the slideshow below for a map of where the coldest temperatures were located on May 6, 1989.

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For more On this Date in Iowa Weather history, please visit our website at: http://www.weather.gov/dmx/wxHistory

 

Iowa Monthly Climate Summary – April 2016

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Temperatures

The statewide average temperature was 49.9°F or 1.0°F above normal (See Figure 1). April 2016 became the 57th warmest April out of 144 years of statewide climate records.  The monthly average temperature at Des Moines was 54.2°F or 2.5°F above normal which was the 22nd warmest March for that station since records began in 1878. At Des Moines, the highest temperature was 83°F on the 3rd and the lowest was 25°F on the 9th.  Waterloo’s monthly average temperature was 49.1°F or 0.2°F above normal. The highest temperature at Waterloo was 80°F on the 16th while the coldest was 16°F on the 9th.

At the beginning and end of the month, temperatures were generally below normal. During the middle weeks of April is when the above normal temperatures prevailed. The warmest period occurred from the 13th to the 26th (See Figure 2). A pair of hard freezes occurred on the 9th and 12th of the month where the 9th was the coldest day across the state (See Figure 3). The coldest temperature of the month was 13°F in Audubon on the 9th. Sheldon, Spencer, and Webster City all recorded 16°F low temperatures on the morning of the 12th.  The month’s highest temperature was 85°F at Little Sioux on the 3rd and then Donnellson reached the same temperature on the 25th. Dreary and damp weather set in across the state during the final four days of the month and kept temperatures well below normal, especially maximum temperatures (See Figure 4).

Precipitation

The statewide precipitation total was 3.07 inches or 0.44 inches below normal. For the entire month, precipitation totals were above normal across western Iowa while the north central to northeast had the lowest amount of precipitation (See Figure 5). April 2016 became the 68th wettest April among 144 years of climate records.  The total precipitation at Des Moines was 3.37 inches or 0.49 inches below normal while Waterloo totaled 2.60 inches or 1.11 inches below normal for the month.

Abnormally dry weather conditions reigned during the first 18 days of April when no measurable precipitation occurred over west central to southwest Iowa (See Figure 6). During the last 12 days of the month, a more active and wet pattern developed across the state (See Figure 7). In fact, the statewide average precipitation during the first 18 days was 0.57 inches, while the final 12 days averaged 2.50 inches.  The hardest hit area was western Iowa the last 2/5 of the month and caused several rivers and streams to become bank full or even reached minor flood stage by early May. April 2016 totals ranged from 0.75 inches at Marquette to 7.52 inches at Alta.  Another comparison, Guttenberg had its driest April since 1942 while Sioux City recorded its wettest April since 1998.  A cold, dreary, and soggy end to the month plagued the entire state, but the precipitation totals were recorded on the morning of the 1st of May and will be recorded in the May 2016 precipitation total.

There was very little severe weather throughout the month as the first 18 days were fairly inactive. Only 2 days had severe weather which were the 24th and 27th of April. Northwest Iowa had high winds and large hail on the 24th while on the 27th had 5 tornadoes that occurred in southwest Iowa, including an EF1 in Stanton, Iowa. For a summary of the event, visit: http://www.weather.gov/dmx/160427summary. As far as non-thunderstorm activity, there were several high wind events that occurred during the first 8 of 9 days of the month.  This is not uncommon as early April is typically the windiest time of year in Iowa.

Blog post by Kenny Podrazik – NWS Des Moines