On This Date in Iowa Weather History: Dunkerton, Iowa F3 Tornado – May 11, 2000

On May 11, 2000, severe thunderstorms produced large hail and at least seven tornadoes across northeastern Iowa including one that killed one person and injured 25 others as it produced F3 damage near Dunkerton, Iowa.  This would be affecting some of the same areas that would be struck by the EF5 Parkersburg tornado eight years later. The largest reported hail stones were the size of baseballs, falling near Dorchester in Allamakee County.

You can find more information regarding this event from the following sources:

http://www.silverliningtours.com/may-11th-2000-dunkerton-iowa-f3-tornado/

http://cbs2iowa.com/news/local/15-years-since-dunkerton-tornado

http://wcfcourier.com/news/top_story/five-years-later-dunkerton-remembers-tornado/article_c812a6b7-5378-57f8-b14e-f312e62955d9.html

 

 

February 2017 Warmth at Des Moines

February of 2017 was remarkably warm across Iowa, including at Des Moines where it was the warmest February on record and continued a streak of 18 consecutive months in which the average temperature has been above normal, dating back to September of 2015. Several daily records were established for warm temperatures in February, including maximum temperature records on the 17th (75°F), 19th (73°F), 21st (68°F) and 22nd (73°F), and a warm minimum temperature record on the 22nd (47°F). During the 28 days of February there were only 4 days with an average temperature below normal, while there were 16 days that were 10+ degrees above normal and 8 days that were 20+ degrees above normal. Here is where the month stacked up in various Des Moines records (going back to 1879):

Warmest February’s on record

  1. 39.2°F (2017)
  2. 38.1°F (1930)
  3. 37.7°F (1954)
  4. 36.9°F (1931)
  5. 36.4°F (2000)

Warmest February days on record

  1. 78°F (2/24/1930)
  2. 75°F (2/17/2017), 75°F (2/15/1921)
  3. 73°F (2/22/2017), 73°F (2/19/2017), 73°F (2/29/1972)

Most 70+ degree days in February

  1. 3 (2017)
  2. 2 (1930)
    (All other years 1 or 0)

Most 60+ degree days in February

  1. 8 (2017)
  2. 7 (1981, 1930)
  3. 6 (2000)
  4. 5 (1999, 1932)

DesMoinesFeb2017Temps

Blog post by Jim Lee, Meteorologist

Spring and Summer Outlooks for Iowa – 2017

Introduction

Now that we’re finally exiting the winter months and well on our way to spring, you’re probably wondering what might be in store for the remainder of spring and summer.  While seasonal forecasting is far from perfect, we can often times get a feel for what may occur based on teleconnections.  What is a teleconnection you ask?  Good question.  In atmospheric sciences, teleconnections are anomalies that have shown a relation to each other.  A great example of a teleconnection that many have heard about is El Nino, or more properly, El Nino-Southern Oscillation (ENSO).  For those that have seen previous seasonal outlooks from our blog, you are probably already familiar with what ENSO is.  For those that are not, take a peek below.

ENSO refers to a phenomenon that exists along the equatorial Pacific Ocean.  It is categorized as El Nino or La Nina depending on the type of anomaly or Neutral if there is no anomaly or a very weak one.  More specifically, El Nino is characterized by anomalously warm seas surface temperatures that propagate eastward towards the South American coast.  Conversely, La Nina is characterized by anomalously cool sea surface temperatures off of the coast of South America that propagate into the central Pacific Ocean.  The oscillation between the two is ENSO.  Do determine whether or not El Nino or La Nina conditions exist, the Oceanic Nino Index (ONI) is used.  The ONI is a measure of above and below normal sea surface temperatures within specific regions of the equatorial Pacific.  For an event to be declared, 5 consecutive over-lapping 3 month periods must be anomalous one way or another by 0.5 deg C or more.  El Nino would be for positive anomalies and La Nina for negative ones.  Anything that does not meet the 5 consecutive period criteria or is within +/- 0.5 deg C is declared Neutral.  Note the difference between conditions and event.  Conditions exist during any 3 month averaging period, while an event takes the 5 consecutive over-lapping 3 month periods mentioned previously. 

At this point, you may be wondering what Pacific Ocean sea surface temperatures have to do with weather in the in the United States, let alone Iowa.  The atmosphere is constantly in flux, responding to various inputs such as ENSO conditions in the Equatorial Pacific in an attempt to reach equilibrium.  Phenomena that last long periods of time and occur regularly can affect atmospheric conditions in ways that lead to tendencies in other areas, teleconnections.  A number of phenomena across the globe have been researched and found to correlate to weather patterns in other locations across the globe, and ENSO is the most researched and well known teleconnection for the United States.  We’ll proceed to take a look at the tendencies for forecasted neutral to El Nino conditions in Iowa for the upcoming Spring and Summer seasons.

For more detailed information about El Nino and La Nina, atmospheric conditions, thresholds, U.S. impacts, global impacts, and more, check out: https://www.climate.gov/enso

For more detailed information about the Oceanic Nino Index, check out: http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

Spring

Currently, Neutral conditions exist within the Nino 3.4 region, having just come out of relatively weak La Nina conditions through winter.  Official ENSO probabilistic forecasts indicate a likely transition towards El Nino conditions within the Nino 3.4 region as spring and summer progresses.  Though focusing on Spring alone, forecasts heavily favor Neutral conditions, which makes sense in the short term considering the region just came out of La Nina conditions.

(Image 1: Official probabilistic ENSO Forecast from the Climate Prediction Center and International Research Institute for Climate and Society)

Noting the heavy lean to neutral conditions within the forecast, we will focus strictly on historical Neutral events for Iowa and surrounding areas during Spring.  It should be noted that with conditions freshly coming off of a La Nina event, atmospheric response, especially as it pertains to the United States, may be in transition throughout Spring as neutral conditions set in.  Historically, temperatures during Neutral conditions have leaned on the cooler side of average for the Upper Midwest and Upper Mississippi Valley’s with Iowa on the southern edge and with only minimal cool departures (Image 2: Temperature Anomalies (F) for previous Neutral events during the Spring).  The analysis for precipitation points towards above average precipitation throughout much of the Mississippi Valley and Upper Midwest, including the entire state of Iowa.  Once again, though, the state finds itself on the lower end of the departures (Image 3: Precipitation anomalies (in) for previous Neutral events during the Spring). For both temperature and precipitation, the largest departures are well away from Iowa, predominantly centered on the south and west. 

Comparatively we’ll take a quick look at the official Climate Prediction Center (CPC) outlooks for Spring as well.  As it pertains to temperatures, the CPC suggests a slightly better opportunity for above normal temperatures versus normal or below normal through Iowa (Image 4: Spring temperature outlook from the Climate Prediction Center).  Looking at precipitation, the CPC indicates a slightly better opportunity for above normal precipitation over northern Iowa, while central and southern Iowa has equal chances for above, below, or normal precipitation (Image 5: Spring precipitation outlook from the Climate Prediction Center).  While the CPC precipitation forecast roughly resembles a nod towards the Neutral analysis, temperatures do not.  Which possibly indicates lingering La Nina influence as the atmosphere continues to respond to incoming Neutral conditions or the influence of other phenomena and atmospheric patterns being taken into consideration.

Summer

Now with summer a couple of months away yet, a bit more uncertainty comes into play for the ENSO forecasts.  Recall the forecast at the beginning showed increasing likelihood of El Nino conditions setting in, but hovered around 40-50%, with Neutral conditions taking up much of the remaining likelihood.  With that in mind, we’ll take a quick look at what both Neutral and El Nino conditions have resulted in historically.  

Examining Neutral conditions first, there is no strong tendency for above or below average precipitation within the state, let alone the surrounding states (Image 6: Precipitation anomalies (in) for previous Neutral events during the Summer). Conversely temperatures do show a tendency to be above average throughout most of Iowa and much of the United States for that matter (Image 7: Temperature anomalies (F) for previous Neutral events during the Summer).   The best tendencies for precipitation reside through the Appalachian region and for temperature the southwest US.  

On the El Nino side of the equation, precipitation tendencies show up within the state and surrounding areas, however they are a bit of a mixed bag of both above and below average (Image 8: Precipitation anomalies (in) for previous El Nino events during the Summer).  On the temperature side, history favors below average temperatures throughout Iowa and surrounding areas, which opposite that of historical Neutral conditions (Image 9: Temperature anomalies (F) for previous El Nino events during the Summer).  In the El Nino case, it is hard to pinpoint the best tendency for precipitation within the United States given the mixed responses, whereas the northern Great Lakes region shows the best tendency for temperatures.   

Once again to give some perspective, we’ll take a quick look at the Climate Prediction Center forecast for the summer months.  At first glance, both the precipitation and temperature summer outlooks from the Climate Prediction Center loosely resemble the Neutral conditions depicted above versus the El Nino ones (Image 10: Spring precipitation outlook from the Climate Prediction Center) (Image 11: Spring temperature outlook from the Climate Prediction Center).  Recall once again that the atmosphere takes time to respond to changes such as ENSO.  Should El Nino make an appearance it will have to traverse through Neutral conditions first, remember we just came out of La Nina, on its way to El Nino.  So void of other influences, it would make a degree of sense that the atmosphere may still be responding to Neutral conditions even if El Nino creeps in.  Of course, ENSO is not the only teleconnection that influences our weather conditions.  Others that have been and are continuing to be researched include the North Atlantic Oscillation, the Madden-Julien Oscillation, the Pacific Decadal Oscillation, and more.  In future editions we may explore how some of these other teleconnections can affect Iowa and the United States.  Until then, we will see how spring and summer play out and whether or not ENSO tendencies appear.

Blog post by: Allan Curtis, Meteorologist Intern

February 2017 Warmth at Waterloo

February of 2017 was remarkably warm across Iowa, including at Waterloo where it was the 4th-warmest February on record (going back to 1895). Daily record maximum temperatures were established on the 17th (69°F), 19th (67°F) and 22nd (69°F). During the 28 days of February there were only 5 days with an average temperature below normal, while there were 15 days that were 10+ degrees above normal and 5 days that were 20+ above normal. Here is where the month stacked up in various Waterloo records:

Warmest Februarys on record
1. 35.2°F (1954)
2. 34.9°F (1931)
3. 34.4°F (1998)
4. 33.6°F (2017)
5. 33.0°F (1930)

Warmest February days on record
1. 71°F (2/15/1921)
2. 69°F (2/22/2017)
    69°F (2/17/2017)
4. 67°F (2/19/2017)
5. 66°F (2/17/1981)
    66°F (2/25/2000)

Most 60°F+ degree days in February
1. 7 (1930)
2. 5 (2017)
3. 4 (1981)
4. 3 (2000)
5. 2 (1921)

WaterlooFeb2017Temps

 

Blog post by Jim Lee, Meteorologist

On this Date in Iowa Weather History: 1959 Girl’s State Basketball Winter Storm

On March 14-16, 1959, a major winter storm struck Iowa as a potent low pressure center moved east northeast out of Kansas into central Illinois resulting in 6 deaths and 1 injury. Precipitation began in southern Iowa as rain on the morning of the 14th then started to switch to a heavy wet snow by afternoon. The heaviest snowfall occurred overnight on the 14th-15th, with 4 inches or more falling in a wide swath from southwest to northeast across the state and some areas within that band receiving 8 to 10 inches. The highest reported storm total snowfall accumulations included 12.5 inches at New Hampton, 12.0 inches at Cresco, and 10.0 inches at Clarion, Fayette, and Fort Dodge. Winds gusting to as high as 60 mph caused severe blowing and drifting of the snow, commonly producing drifts up to 10 feet deep. There were even reports in northeastern Iowa with drifts as deep as 15 feet! Across about the southern half of the state, the heavy snow remained very wet and froze to all surfaces. As a result, thousands of trees, utility poles and lines were snapped or heavily damaged. Even after the heavy snow ended on the 15th, frozen surfaces and high winds continued to make travel impossible across most of the state. In fact, Des Moines and Dubuque authorities prohibited any travel to or from their cities. Also in Des Moines, there were 5,000 basketball fans attending the girls state tournament that spent the night in the Veterans Memorial Stadium building.

SnowfallTotals-March14-16_1959

On This Date In Iowa Weather History – 1991 Halloween Storm

1991: A major winter storm pounded the upper Midwest from October 30th into November 2nd with some of the most severe effects occurring on Halloween. Snow moved into southern Iowa on the afternoon of the 30th and changed to mixed precipitation and ice on the morning of the 31st and continuing into late afternoon on November 1st. Total ice accumulations ranged from 1 to 2 inches from southwest into north central Iowa and 2 to 3 inches across southern and southeast Minnesota. In northwest Iowa, the precipitation fell as all snow. Total snow accumulations of 8 inches or more blanketed the area with 15.0 inches falling at Estherville. Stong winds produced blizzard conditions into November 2nd. The damage and hazardous travel conditions were so severe and extensive that 52 of the 99 counties in Iowa were declared disaster areas. Highways and interstates were closed across most of the state and Halloween festivities were cancelled at many locations. As the storm system moved further northeast it dumped 36.9 inches of snow at Duluth which, at the time, was the largest storm total snowfall accumulation on record in Minnesota until it was surpassed in 1994. 

Extreme cold followed the crippling Halloween Storm from November 4-8, 1991.  With the fresh snow pack in place, on November 4th nearly every reporting station in the state fell into the single digits and remarkably some western stations reported their earliest subzero temperatures on record, including Sioux City where the low was -3°F. Des Moines and Waterloo both established daily records with a low of 4°F. The lowest temperatures reported on the morning of the 4th included -7°F at Sioux Rapids, -9°F at Hawarden, -10°F at Sheldon, and -11°F at Cherokee. Amazingly, even colder weather would settle across Iowa a few days later with nearly the entire state falling below zero on the mornings of November 7th and 8th.  On the 7th many stations set daily record lows and at numerous locations this is the earliest date on record on which the temperature has fallen below zero, including at Des Moines where the low was -3°F. The lowest reported temperatures in Iowa that morning included -12°F at Audubon, -13°F at Perry, -14°F at Le Mars, -15°F at Sheldon, -16°F at Guthrie Center, -17°F at Cherokee, and -19°F at Hawarden.  On the morning of the 8th reported low temperatures included -2°F at Burlington, -8°F at Bedford and Grinnell, -11°F at Sac City, -12°F at Atlantic and Le Mars, -13°F at Cherokee and Perry, and -14°F at Guthrie Center.

 

Other Stories or Resources on the 1991 Halloween Winter Storm/Blizzard 

https://en.wikipedia.org/wiki/1991_Halloween_blizzard

http://www.startribune.com/25-photos-that-perfectly-capture-the-halloween-blizzard-of-1991/338843092/#1

http://climate.umn.edu/doc/journal/halloween_blizzard.htm

http://www.weather.gov/dlh/1991halloweenblizzard (NWS WFO Duluth)

http://www.weather.gov/arx/halloween1991 (NWS WFO La Crosse)

https://www.ncdc.noaa.gov/news/month-climate-history-halloween-blizzard-1991

On this Date in Iowa Weather History – 1997

October 25-26, 1997

A major winter storm moved into western Iowa just before midnight on October 25th and spread across about the southeastern two thirds of the state on the 26th. Two bands of heavy snow developed, one extending from Council Bluffs northeast through Boone and the other extending from northern Ringgold County northeast to around Cedar Rapids. The heaviest snowfall accumulations included 11.3 inches at Knoxville and an amazing 13.0 inches southwest of Mineola in Pottawattamie County. Electricity was lost to tens of thousands of homes and businesses in central and southern Iowa as snow laden trees fell onto power lines. This was the most significant heavy snow so early in the season in Iowa since the storm of October 16-17, 1898. On the morning of the 27th temperatures plummeted, with the aid of the fresh snow pack on the ground, bottoming out at 9 F at Atlantic and Guthrie Center which was the coldest Iowa temperature recorded so early in the season since 1972. While this system produced nearly all of the snow that fell during the month of October 1997, it was still enough to make it the third-snowiest October on record in Iowa only behind those of 1898 and 1925.

Fall and Winter Outlooks for Iowa

Introduction

The talk all winter and spring was El Niño and how it would affect large portions of the United States.  As spring ended and summer took over, El Niño conversations were quickly replaced with La Niña thoughts as conditions began to transition.  Taking a step back, for those that are unfamiliar with the terms El Niño or La Niña, they are phenomena that exist along the equatorial Pacific Ocean.  An El Niño event is characterized by anomalously warm sea surface temperatures that propagate eastward towards the South American coast.  Conversely, a La Niña event is characterized by anomalously cool sea surface temperatures off the coast of South America that propagate into the central Pacific Ocean.  The oscillation between the two is called the El Niño-Southern Oscillation (ENSO).  For an event to be categorized as an El Niño or La Niña, the Oceanic Niño Index (ONI) is used.  The ONI is a measure of above and below normal sea surface temperatures within a specific region of the equatorial Pacific.  Anomalous values of 0.5 C or greater for 5 consecutive over-lapping seasons would be an El Niño.  Conversely, values of -0.5 C or less for 5 consecutive over-lapping seasons would be a La Niña.  In between 0.5 C and -0.5 C or for periods that do not meet the 5 consecutive over-lapping seasons, would be categorized as neutral.

At this point, you may be wondering what Pacific Ocean sea surface temperatures have to do with weather in the United States, let alone Iowa.  The atmosphere is constantly in flux, responding to various inputs such as El Niño or La Niña conditions in the Equatorial Pacific, in an attempt to reach equilibrium.  Phenomena that last long periods of time and occur regularly can affect atmospheric conditions in ways that lead to tendencies in other areas, known as teleconnections.  A number of phenomena across the globe have been researched and found to correlate to weather patterns in other locations across the globe, and El Niño and La Niña are probably the most researched and well known teleconnections.  We’ll proceed to take a look at the tendencies in Iowa during neutral and La Niña conditions and how they compare to the current seasonal outlooks from the Climate Prediction Center.

For more detailed information about El Niño and La Niña, atmospheric conditions, thresholds, U.S. impacts, global impacts, and more, check out: https://www.climate.gov/enso

For more detailed information about the Oceanic Niño Index, check out: http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

Fall

As hinted at above, El Niño conditions existed through the winter and spring months, but weakened into summer and are forecast to continue into at least neutral conditions and possibly transition into La Niña conditions through the fall months (Image 1)

(Image 1: Official probabilistic ENSO Forecast from the Climate Prediction Center and International Research Institute for Climate and Society)

Image 1: Official probabilistic ENSO Forecast from the Climate Prediction Center and International Research Institute for Climate and Society.

First, focusing on neutral conditions, when looking at previous historical neutral events that occurred during the fall months, temperatures have a tendency to be cooler throughout the state (Image 2).  On the other hand, precipitation does not have a strong tendency state wide, and instead is a mixed bag, indicating a weaker correlation (Image 3).

Should La Niña conditions set in, once again the strongest tendency is seen in temperatures, however this time it is for warmer temperatures throughout the state (Image 4).  Then similarly to neutral, precipitation does not show a strong tendency, but does lean toward slightly drier conditions (Image 5).

While all of that is well and good, how does all of it compare with the Climate Prediction Center’s (CPC) official fall outlook?  For their most recent fall outlook, temperatures nationwide show an increased chance for above normal temperatures (Image 6).  The precipitation outlook shows no tendency for above or below normal precipitation for much of the United States, including Iowa (Image 7).  When comparing to the neutral and La Niña tendencies above, the outlooks do not closely resemble either, possibly indicating low confidence or another teleconnection playing a significant role.

Winter

Shifting towards winter, forecasts show a likely probability of La Niña conditions setting in and that’s what we will focus on here.  La Niña has a pretty strong signal across the United States, however Iowa is caught in the transition zone of above normal temperatures to the south and below normal temperatures to the north (Image 8).  Precipitation, also has a decent signal across the United States, but once again Iowa does not fall within an area of anomalies one way or another (Image 9).  Instead, the best signals are found through the Ohio River valley, Pacific Northwest, the Southeast, and California.

When compared to the CPC outlook for winter, striking resemblances are immediately seen. The strongest resemblance is seen within temperatures, where the CPC highlights the Southeast and South for above normal temperatures and the North for below normal temperatures (Image 10).  Strong resemblances are also seen in the CPC outlook for precipitation, where the Ohio River Valley and Pacific Northwest are highlighted for above normal precipitation, and the Southeast, South, and California for below normal precipitation (Image 11).  Unfortunately for Iowa, with the seeming strong tendency for the CPC outlooks to lean towards La Niña conditions this winter, the CPC does not depict strong feelings one way or the other for precipitation or temperatures. 

Blog post by Allan Curtis, Meteorologist Intern, NWS Des Moines

 

Iowa Monthly Climate Summary – July 2016

Temperatures

The statewide average temperature for July 2016 was 73.0°F which was 0.6°F below normal (See Figure 1). July 2016 ranks as the 50th coolest July on record out of 144 years of statewide climatic records.  The monthly average temperature at Des Moines was 76.8°F or 0.5°F above normal with the highest temperature coming in at 97°F on the 21st and lowest temperature at 58°F on the 1st.  Waterloo’s monthly average temperature was 72.8°F or 0.8°F below normal.  The highest temperature in Waterloo for the month of July was 93°F on the 21st and 52°F on the 3rd.

Through the 4th of July weekend, cooler than normal temperatures prevailed across the state (See Figure 2).  In fact, a few locations recorded low temperatures in the 40s on the morning of the 3rd (See Figure 3).  Estherville, Elkader, and Cresco all had low temperatures at 47°F on July 3rd.  Then the hot and humid conditions developed and dominated throughout much of the remainder of the month.  There were a few days peppered into the last 3 weeks of the month when cloud cover and thunderstorms kept temperatures below normal.  Regardless, the hottest stretch occurred from the 17th to the 27th. The hottest temperature of the month throughout the entire state was 97°F on the 20th at Sioux City and at Des Moines and Lamoni on the 21st.  Much of the state had heat index readings well over 100°F between the 20th and 23rd (See Figures 4 & 5) due to the high humidity and dew points.

Precipitation

The monthly statewide precipitation total for Iowa during the month of July 2016 was 6.13 inches (See Figure 6).  This was 1.63 inches above normal, resulting in the 16th wettest July on record among 144 years of statewide climatic records.  Des Moines totaled 6.98 inches for the month, with the bulk of that total occurring on the 19th when 3.53 inches of rain fell. This daily total nearly doubled its monthly total up to that point. In fact, only 0.02 inches of additional rainfall accumulated the remainder of the month, but Des Moines was still 2.51 inches above normal for the entire month.  Waterloo had a different outcome with 4.01 inches or 0.90 inches below normal for July.

After a dry first five days of the month, an active weather pattern developed and brought a multitude of precipitation through the 20th.  The statewide average from July 6th to the 20th was 4.86 inches or 2.63 inches above normal during that stretch (See Figure 7 & 8). The heaviest rainfall occurred from the southwest to north central to northeast portions of the state. Enough rain fell over central and southern Iowa to relieve some of the drought conditions except for a small area in far south central Iowa (See Figure 9).

Iowa Monthly Climate Summary – May 2016

Temperatures

The statewide average temperature in May 2016 was 59.5°F which was 0.6°F below normal (See Figure 1). This ranks as the 65th coolest May on record out of 144 years of statewide climate statistics.  Des Moines’s average temperature was 63.0°F or 0.7°F above normal while Waterloo’s monthly average temperature 59.9°F or 0.6°F below normal.

A cold snap occurred during the first five days of May as a few spots reported light frost on the mornings of the 2nd, 3rd, and 5th (See Figure 2).  However, by the second week of May, temperatures were above normal with a few locations topping 90°F for the first time in 2016 in Iowa. Marion, Guttenberg, and Hawarden reached 90°F on the 6th. More cool temperatures filter into the state from the 12th to the 21st.  In fact, freezing temperatures were recorded on the 14th, 15th, and 18th with the coldest day and most widespread frost occurring on the 15th (See Figure 3). Cresco, Decorah, and Elkader all recorded 27°F low temperatures on the morning of the 15th.  The remainder of the month, temperatures finished above normal with a string of 10 consecutive warmer than normal days. The hottest temperature was 89°F in Little Sioux and Lamoni on the 30th.

Precipitation

The statewide average precipitation for May 2016 was 4.64 inches or 0.08 inches above normal. This ranks as the 52nd wettest May among 144 years of statewide climate records. Des Moines was 0.62 inches below normal for the location’s monthly precipitation as it totaled 4.12 inches. Waterloo totaled 3.24 inches of rainfall for the month of May, which was 1.29 inches below normal.

The first day of May was cool and wet before generally dry weather prevailed from the 2nd to 8th.  From the 9th to the 13th, a wet period settled into the state with several weak systems that brought light to moderate rainfall. The highest precipitation accumulated over southwest Iowa (See Figure 4).  A couple of brief tornadoes were spotted in Davis and Guthrie Counties County on the 9th, mainly damaging crops and trees. Another relatively dry period dominated the middle of the month from the 14th to the 22nd before a fairly active weather pattern developed to finish off the month. Severe weather plagued the state every day during the final week of the month with the most active night occurring on the 25th. Widespread damaging winds along with some large hail were reported in 19 counties across the northern two-thirds of Iowa. The dries weather was found over central to southeast Iowa, while the bulk of the monthly precipitation accumulated over northwest to southwest Iowa (See Figure 5).  The highest monthly precipitation was 10.75 inches at Atlantic while the lowest monthly total was 2.19 inches in Albia. In fact, Atlantic’s total was its 2nd highest total out of 130 years of records. The highest total is 12.37 inches set in 1903.

Blog post by Kenny Podrazik, Meteorologist, NWS Des Moines