Monthly Climate Summaries

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.

Average Temperature Departure from Mean for May 2016.
Average Temperature Departure from Mean for May 1-5, 2016.
Average Minimum Temperature Departure from Mean for May 15, 2016.

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.

Accumulated precipitation from May 9-13, 2016.
Accumulated precipitation percent of mean for entire month of May 2016.

Blog post by Kenny Podrazik, Meteorologist, NWS Des Moines

Iowa Monthly Climate Summary – June 2016

Temperatures

The statewide monthly average temperature was 73.2°F or 3.5°F above normal (See Figure 1). June 2016 ranks as the 14th warmest June among 144 years of statewide climate records. A warmer June was last recorded in 1991. The average temperature at Des Moines and Waterloo was 77.3°F and 71.9°F respectively.  Des Moines was 5.5°F above normal while Waterloo was only 1.9°F above its monthly average. On the 15th, the hottest temperature of 96°F was recorded for the month at Des Moines while the coldest temperature was 56°F on the 2nd. The hottest temperature at Waterloo was 95°F on the 10th while just two days earlier the low temperature dropped to 46°F.

Above normal temperatures prevailed for the majority of month of June across the state. A long hot spell occurred from the 9th to the 20th when the hottest temperature of 100°F was recorded at Little Sioux on the 11th (See Figure 2). This 100°F ended up being the hottest temperature for the entire state during June 2016 and was Iowa’s first triple-digit temperature since September 10, 2013. The state’s second longest streak without a 100°F reading ended on the 11th with 1,004 consecutive days. The longest streak is 1,438 consecutive days from August 3, 1991 to July 9, 1995.  The maximum temperature at Des Moines from the 9th to the 27th was 85°F or higher for 19 consecutive days in June.  This became the longest streak of its kind during the month of June since 1878 at Des Moines. The previous longest stretch was 17 consecutive days set in June 1956.

Precipitation

The statewide average precipitation was 3.69 inches which was 1.33 inches below the state’s normal for June (See Figures 3 & 4). This ranks as the 45th driest June out of 144 years of statewide climate records. The monthly totals at Des Moines and Waterloo were 1.47” or 3.47” below normal and 8.97” or 4.98” above normal. Des Moines recorded its 10th driest June since 1878 and Waterloo recorded its 4th wettest June since 1895. This was common throughout the state as the precipitation was highly variable (See Figure 5). For example, Cedar Falls had a whopping 11.22” while Salem only recorded 0.25” for the entire month. By the end of the month, much of south central to southeast Iowa were placed into Moderate Drought by the U.S. Drought Monitor with much of the southwest to western part of the state classified as Abnormally Dry (See Figure 6). Severe weather was limited throughout the month of June, even though June is Iowa’s peak severe weather month. In fact, the first half of 2016 was fairly “quiet” with respect to severe weather (See Figures 7a/7b).  The most active day came on June 14th when several central to northern Iowa counties reported wind damage. Heavy rain and damaging winds plagued a few counties during the evening of the 25th into the early morning on 26th (See Figure 8). Flooding was also limited during the month with only 1 river reaching flood stage and just a handful of Flash Flood Warnings issued by National Weather Service Office in Des Moines.

The U.S. Drought Monitor issued on June 28, 2016 placed Moderate Drought over south-central to southeast portions of Iowa and Abnormally Dry conditions over central to western Iowa.
Heavy rain fell over southwest to east-central Iowa during the overnight hours from the 25th to the 26th. 24-hour precipitation ending at 7 AM CDT June 26, 2016.
Year-to-Date NWS Severe Thunderstorm Warnings ending on June 29, 2016. NWS Des Moines only issued 60 Severe Thunderstorm Warnings, but from 2005 to 2015, NWS Des Moines averaged 292 Severe Thunderstorm Warnings per season. Image Courtesy of Iowa Environmental Mesonet.
Year-to-Date NWS Tornado Warnings ending on June 29, 2016. NWS Des Moines had only issued 4 tornado warnings up until that point. Image is courtesy Iowa Environmental Mesonet.
Blog post by Kenny Podrazik, Meteorologist, NWS Des Moines

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

September 2015 Iowa Climate Review

Temperatures

The average statewide temperature during the month of September was 68.5°F which was 5.3°F above normal (See Figure 1). September 2015 became the 7th warmest September among the 143 years of state climate records. Des Moines’ average monthly temperature was 71.9°F or 6.3°F above normal. The coldest temperature of the month at Des Moines was 47°F on the 30th while the hottest temperature reached 94°F on the 6th. Waterloo was also well above normal for monthly average temperature with an average of 68.3°F or 5.3°F above normal. The coldest temperature at Waterloo in September was 39°F on the 30th while the warmest temperature was 92°F on the 6th. 90 degree temperatures were fairly common during the first week of September. In fact, the first seven days of the month were the warmest week of the year in the state with temperatures averaging 10.6° above normal (See Figure 2).

When temperatures were above normal during September, they were well above normal with some of the warmest stretches occurring from the 3rd to 7th, 15th to 17th, and 22nd to 25th. In fact, Des Moines had more days (13) when the average daily temperature was at least 10°F greater than normal, than it had days when the average temperature dropped below normal (7). Waterloo only had 6 days when the daily average temperatures was below normal and had 11 days when daily average temperature was at least 10°F or greater than normal. A cold front pushed through the state at the end of the month and brought some temperatures in the 30s across northern Iowa. Estherville and Cresco dropped to 33°F on the 30th.

Figure 1: Average temperature departure from normal for the month of September 2015. Map is courtesy of MRCC.

Figure 1: Average temperature departure from normal for the month of September 2015. Map is courtesy of MRCC.

Figure 2: Average temperature departure from normal during the first week of September 2015. Map is courtesy of MRCC.

Figure 2: Average temperature departure from normal during the first week of September 2015. Map is courtesy of MRCC.

















Precipitation

The average statewide precipitation was 4.08 inches or only 0.70 inches above normal (See Figure 3). September 2015 becomes the 50th wettest September among 143 years of statewide records. It was a “hit-or-miss” for precipitation during the month of September with the west to southwest portions of the state receiving the bulk of the rain and the north to east the less amounts (See Figure 4). Typically when it rained in September, it rained in abundance but in isolated areas. Fort Dodge for instance only received 0.90 inches while Glenwood reported 11.63 inches for the month. Des Moines and Waterloo had 5.25 inches and 2.59 inches respectively. Torrential rains fell over portions of central to southwest Iowa during the overnight hours from the 6th to the 7th and caused some significant flash flooding in Carroll, Guthrie, and Greene counties. The towns of Bagley, Coon Rapids, Bayard, Glidden, and Carroll all had significant impacts due to flash flooding (See Figure 5), with major state Highway 141 receiving water over it in multiple locations. Radar estimated rainfall amounts ranged from 3 to 8 inches on the night of the 6th (See Figure 6) with a report of 6.25 inches from a spotter in Bagley. Portions of southeast Iowa also had 2 to 4 inches of rain from the 6th to 7th. On the 23rd, western Iowa received a round of torrential rain and mainly affected the Council Bluffs area. In fact, a storm total of 9.28 inches was reported on the north edge of Council Bluffs. Severe weather was fairly limited across the state during the month of September with a few reports of large hail and damaging winds on the 6th and then again on the 10th to the 11th.

Figure 3: September 2015 total precipitation for the month across Iowa shows the west to southwest received the most significant amounts with the far eastern corners of the state the lowest amounts.

Figure 3: September 2015 total precipitation for the month across Iowa shows the west to southwest received the most significant amounts with the far eastern corners of the state the lowest amounts.

Figure 4: Average precipitation departure from normal for the month of September 2015. Map is courtesy of MRCC.

Figure 4: Average precipitation departure from normal for the month of September 2015. Map is courtesy of MRCC.

Figure 5a: Flash flooding photos from Carroll on September 6, 2015. Photos are courtesy of KCCI and Iowa Storm Chasing Network.

Figure 5a: Flash flooding photos from Carroll on September 6, 2015. Photos are courtesy of KCCI and Iowa Storm Chasing Network.

Figure 5b: Flash flooding photos from Carroll on September 6, 2015. Photos are courtesy of KCCI and Iowa Storm Chasing Network.

Figure 5b: Flash flooding photos from Carroll on September 6, 2015. Photos are courtesy of KCCI and Iowa Storm Chasing Network.

Figure 6: Radar estimated rainfall amounts from September 6-7, 2015 show a very heavy swath of rain from Coon Rapids to Bayard to Rippey Iowa.

Figure 6: Radar estimated rainfall amounts from September 6-7, 2015 show a very heavy swath of rain from Coon Rapids to Bayard to Rippey Iowa.

Blog post by Kenny Podrazik – NWS Des Moines

August 2015 Iowa Monthly Climate Review

Temperatures

The statewide average temperature for Iowa in August 2015 was 69.2°F which was 2.3°F below normal (See Figure 1). August 2015 became the 27th coolest August out of 143 years of records for the state of Iowa. This is the 4th consecutive month with the temperatures being below normal. Actually, throughout the month of August 2015, there were no long duration heat waves, just a few isolated days reaching the lower 90s early in the month. The hottest temperature in the state during the entire month was only 94°F at Sheldon on the 2nd. Des Moines recorded 93°F on the same day and that was 1 of only 2 days in which Des Moines reached 90°F or greater. The 2nd time was on the 7th when it reached 90°F on the nose. The coldest temperature throughout the month was 40°F in Spencer on the 25th. The coldest high temperature at Des Moines was 68°F on the 19th and the lowest temperature was 53°F on the 25th and 26th. Waterloo reached exactly 90°F only once and that occurred on the 2nd and its coldest temperature in August was 45°F on the 26th. On the 18th and 19th, Waterloo had back-to-back days of highs remaining in the 60s and from the 18th to the end of the month, only 2 days had a daily average temperatures that were above normal. Waterloo for the month was 2.4°F below normal for a monthly average temperature while Des Moines was 1.2°F below normal for a monthly average temperature. In Ottumwa, it was 2.7°F below its normal monthly average temperature for August.

Figure 1: Average statewide monthly temperature departure from normal for August 2015. Image is courtesy of High Plains Regional Climate Center (HPRCC).

Figure 1: Average statewide monthly temperature departure from normal for August 2015. Image is courtesy of High Plains Regional Climate Center (HPRCC).

Precipitation

The average statewide precipitation was 5.42 inches or 1.22 inches above normal for the month of August 2015 (See Figures 2 to 4). This is the 21st wettest August among 143 years of records and was the fourth consecutive month with above normal rainfall. The average statewide precipitation during the first half of August was 1.30 inches which was 0.92 inches below normal. A few light rain events occurred during the first couple of weeks with only one significant severe weather event on the 2nd and a heavy rain event that transpired on the evening of the 8th into the early morning on the 9th. On August 2nd, a tornado brought EF1 damage to Adair and Adams Counties as it was on the ground for 36 minutes covering 7.54 miles (See Figures 5 & 6). During the 8th and 9th, a swath of heavy rain fell from Webster County through Story, Boone, and Jasper Counties and southeast into Poweshiek County where roughly 2 to 5 inches of rain fell (See Figure 7). Heavy rain also fell over portions of far southwest Iowa on the 8th. The highest preliminary rainfall report was 7.00” in Otho, Iowa in Webster County on August 8, 2015. More widespread rain events occurred during the final two weeks of the month when the state averaged 4.12 inches or 2.14 inches above normal during that time frame. Heavy rain fell on the 17th and 18th over central to northwest Iowa (See Figure 8). Des Moines picked up 2.46 inches on the 18th, well over half of its monthly total of 4.25 inches. However, the most notable heavy rain event occurred on the 28th when a widespread 3 to 7 inches fell over portions of central Iowa with an isolated amount over 9 inches reported in Dayton, Iowa in Southeast Webster County (See Figure 9). A major flash flood on the Skillet Creek affected much of the town of Dayton as a result of the large amount of rain (See Figures 10 & 11). One other notable event that was related to weather was a lightning strike on August 23 that struck a corn stover bale storage unit near Maxwell and set it on fire (See Figure 12). The fire blazed for roughly a full day before burning out and was seen on radar for a good portion of the day on August 23 (See Figure 13).

Figure 2: Total precipitation for the state of Iowa during August 2015.

Figure 2: Total precipitation for the state of Iowa during August 2015.

Figure 3: Total precipitation departure from normal for the state of Iowa during August 2015.

Figure 3: Total precipitation departure from normal for the state of Iowa during August 2015.

Figure 4: Total precipitation percent of mean for the state of Iowa during August 2015.

Figure 4: Total precipitation percent of mean for the state of Iowa during August 2015.

Figure 5: August 2, 2015 EF1 tornado track in Adair and Adams County.

Figure 5: August 2, 2015 EF1 tornado track in Adair and Adams County.

Figure 6: August 2, 2015 EF1 tornado track in Adair and Adams County. Photo is courtesy of Adam Amdor via Twitter (@Amdor_7).

Figure 6: August 2, 2015 EF1 tornado track in Adair and Adams County. Photo is courtesy of Adam Amdor via Twitter (@Amdor_7).

Figure 7: August 8-9, 2015 observed precipitation.

Figure 7: August 8-9, 2015 observed precipitation.

Figures 10 & 11: Major Flash Flooding on the Skillet Creek affected the Golf course and Campground in Dayton, Iowa. Photos are courtesy of James Hobbs and Jennifer Eckert.

Figure 10: Major Flash Flooding on the Skillet Creek affected the Golf course in Dayton, Iowa. Photo is courtesy of James Hobbs and Jennifer Eckert.

Figures 10 & 11: Major Flash Flooding on the Skillet Creek affected the Golf course and Campground in Dayton, Iowa. Photos are courtesy of James Hobbs and Jennifer Eckert.

Figure 11: Major Flash Flooding on the Skillet Creek affected the Campground in Dayton, Iowa. Photo is courtesy of James Hobbs and Jennifer Eckert.

Figure 8: Q3 radar estimated precipitation from August 18, 2015.

Figure 8: Q3 radar estimated precipitation from August 18, 2015.

Figure 9: The observed significant amount of rain on August 28, 2015.

Figure 9: The observed significant amount of rain on August 28, 2015.

Figure 12: Lightning started a fire of a corn stover storage unit near Maxwell, Iowa on August 28, 2015. Photo is courtesy of Melissa Spencer, Story County EMA.

Figure 12: Lightning started a fire of a corn stover storage unit near Maxwell, Iowa on August 28, 2015. Photo is courtesy of Melissa Spencer, Story County EMA.

Statewide climate statistics courtesy of State Climatologist Harry Hillaker: http://www.iowaagriculture.gov/climatology/weatherSummaries/2015/pms201508.pdf
Blog Post by Kenny Podrazik – NWS Des Moines

July 2015 Iowa Monthly Review

Temperatures

The statewide average temperature for July 2015 was 72.2°F or 1.4°F resulting in the 27th coolest July out of 143 years of statewide climate records (See Figure 1). Unseasonably cool temperatures resulted in below normal values during the first week and a half of July (See Figure 2), which was the primary culprit for the entire month being below normal. Des Moines saw 3 days when the average daily temperature was 10-11°F below normal and Waterloo had 4 days in which the daily average temperature was 11-12°F below normal. Low temperatures dipped into the lower 50s over much of central Iowa through the 10th. 44°F was the coldest temperature during the month and occurred in Cresco and Elkader on the 2nd and then again on the 3rd at Spencer. Lamoni and Ottumwa set new record low temperatures on the 8th with minimums of 57°F and 55°F respectively. Both records were previously set back in 2006 and Lamoni’s previous record was 61°F and Ottumwa’s was 56°F. Summer-like temperatures returned during the middle of the month (13th to 20th). The overnight lows were well above normal and was the main reason this period resulted in being above normal for average temperatures (See Figures 3 & 4). One of the hottest days of the month occurred on the 13th when temperatures rose well into the 90s. Des Moines had the warmest temperature during the month when it topped 97°F on the 13th, but just a few days later on the 17th, Bellevue, Lamoni, and Osceola rose 97°F on the 17th. Hot and humid conditions affected the state during the middle of the month when heat index readings of 105°F to 111°F were reported from the 11th to 13th (See Figure 5). Temperatures through the last 10 days were relatively normal with a couple of hot days occurring on the 24th and 28th when heat index readings jumped back to 100°F to 110°F.

Figure 1: Average Maximum Temperatures Departure from Mean during July 2015 shows maximum temperatures were below normal.

Figure 1: Average Maximum Temperatures Departure from Mean during July 2015 shows maximum temperatures were below normal.

Figure 2: Average Temperature Departure from Mean from July 1 to July 10, 2015.

Figure 2: Average Temperature Departure from Mean from July 1 to July 10, 2015.

Figure 3: Average Maximum Temperature Departure from Mean from July 13 to July 20, 2015.

Figure 3: Average Maximum Temperature Departure from Mean from July 13 to July 20, 2015.

Figure 4: Average Maximum Temperature Departure from Mean from July 13 to July 20, 2015.

Figure 4: Average Maximum Temperature Departure from Mean from July 13 to July 20, 2015.

Figure 5: Maximum Heat Index Forecast for July 13, 2015.

Figure 5: Maximum Heat Index Forecast for July 13, 2015.

Precipitation

The statewide average precipitation was 5.71 inches or 1.21 inches above normal which made July 2015 the 19th wettest July out of 143 years of statewide precipitation records (See Figures 6 & 7). However, dry conditions affected the state during the first couple of weeks as the statewide average precipitation was 1.64 inches (See Figure 8). Normal value is 2.28 inches during this time frame. In fact, the first half was so dry that ‘abnormally dry’ conditions crept into northwest Iowa by July 14 according to the Drought Monitor (See Figure 9). The last half of the month however was much more active and the statewide average precipitation was 4.07 inches (See Figure 10). Normal during that period is 2.22 inches. There were a few days during the first half the month where with locally heavy rain occurred. The 6th and the 15th all had locally heavy rain over portions of southern to southeast Iowa, while on the 11th more widespread rain cause some flash flooding over southern Iowa (See Figure 11). The most active week for rainfall was from July 24th to the 28th, with southern Iowa receiving the majority of the rain (See Figure 12). However, northern Iowa had its share of heavy rain on the 24th when Mason City picked up 4.13 inches. Spring Hill, in Warren County, received the month’s heaviest rain on the night of the 28th with 6.32 inches. The monthly rainfall totals ranged from a low of 1.20 inches in Dubuque to a whopping 13.33 inches in Knoxville. Des Moines totaled 7.17 inches which was 2.70 inches above normal and Waterloo totaled 5.56 inches or 1.29 inches above normal. In fact, Des Moines had 7 days with measurable precipitation from July 15-28 and had 3 consecutive days with 1 inch or more from 26-28.

Severe weather was limited during the month of July with just a handful of localized areas that were impacted over central Iowa. In fact, the NWS Des Moines office did not issue a Severe Thunderstorm Warning until July 13! One notable event occurred on July 16 when several reports of funnel clouds were received late in the afternoon in Story County (See Figures 13 & 14).

Figure 6: Accumulated Precipitation during the month of July 2015.

Figure 6: Accumulated Precipitation during the month of July 2015.

Figure 7: Accumulated Precipitation Percent of Mean during the month of July 2015. Southern received the bulk of the rainfall.

Figure 7: Accumulated Precipitation Percent of Mean during the month of July 2015. Southern received the bulk of the rainfall.

Figure 8: Accumulated Precipitation Department from Mean from July 1 to July 14, 2015.

Figure 8: Accumulated Precipitation Department from Mean from July 1 to July 14, 2015.

Figure 10: Accumulated Precipitation Department from Mean from July 15 to July 31, 2015.

Figure 10: Accumulated Precipitation Department from Mean from July 15 to July 31, 2015.

Figure 9: U.S. Drought Monitor showed drought conditions creeping into northwest Iowa.

Figure 9: U.S. Drought Monitor showed drought conditions creeping into northwest Iowa.

Figure 11: Radar estimated precipitation on July 11, 2015 over southern Iowa. A widespread swath of 3-5 inches accumulated with a few locally higher amounts.

Figure 11: Radar estimated precipitation on July 11, 2015 over southern Iowa. A widespread swath of 3-5 inches accumulated with a few locally higher amounts.

Figure 12: 5-Day radar estimated precipitation ending 10:41 p.m. on July 29, 2015 where the most of the heavy rain fell over southern Iowa.

Figure 12: 5-Day radar estimated precipitation ending 10:41 p.m. on July 29, 2015 where the most of the heavy rain fell over southern Iowa.

Figures 13 & 14: Reports of funnel clouds on July 13 near Ames, Iowa were shown on Twitter.

Figures 13: Reports of funnel clouds on July 13 near Ames, Iowa were shown on Twitter.

Figures 13 & 14: Reports of funnel clouds on July 13 near Ames, Iowa were shown on Twitter.

Figures 14: Reports of funnel clouds on July 13 near Ames, Iowa were shown on Twitter.

A few statewide climate statistics were courtesy of State Climatologist Harry Hillaker: http://www.iowaagriculture.gov/climatology/weatherSummaries/2015/pms201507.pdf
Blog Post by Kenny Podrazik – NWS Des Moines

Iowa Monthly Climate Summary – May 2015

Temperatures

The statewide (Iowa) average temperature for May 2015 was 60° which was only 0.1° below normal (See Figure 1). May 2015 ranks as the 69th warmest May out of 143 years of statewide records. The month of May witnessed several big temperature swings with the first third of the month (2nd to 10th) beginning well above normal before an extended period of chilly weather (11th to 22nd) settle into Iowa during the middle of the month. The coldest days were from the 18th to 21st where most stations ranged from 10 to 15 below their respective normal values (See Figure 2). Waterloo on the 20th had an average temperature of 45° which was 17 degrees under its normal. There were a couple additional days at the end of the month when the daily average temperature dipped to near 10 below normal. However, prior to the aforementioned two days, temperatures generally ranged slightly above normal. The coldest temperature at Des Moines and Waterloo was 39° (19th) and 34° (1st) respectively. The coldest temperature in the state throughout May was 31° at Elkader and Lowden on the 1st while the hottest temperature was 89° at Little Sioux on the 3rd. In fact, the last time when temperatures did not reach 90° during the month of May was in 1995.

AvgTemp_DfM_May_2015 Figure 1: Average temperature departure from mean during the month of May 2015.

AvgTemp_DfM_May18-21_2015 Figure 2: Average temperature departure from mean during the stretch from May 18 to May 21, 2015.

Precipitation

The statewide average precipitation tallied 5.13 inches or 0.57 inches above normal (See Figures 3 & 4). May 2015 became the 35th wettest May among 143 years of statewide records. The rain fell quite regularly throughout the month as measurable precipitation fell on an average of 16.3 days for any single location. This was 39% more frequent than a typical May. Here’s a list of some of the stations that recorded at least 0.01” or more throughout the month:

Stations across central Iowa that recorded several days with measurable precipitation during the month of May 2015.

Stations across central Iowa that recorded several days with measurable precipitation during the month of May 2015.

Monthly rainfall totals ranged from 2.58 inches in Newton to 9.21 inches near Denison. Des Moines ended up 0.41 inches below normal for month even though the station recorded 16 days of measurable precipitation. Waterloo was 0.34 inches above normal for the month, while Mason City was 1.35 inches below its normal for May. The heaviest rainfall fell over west-central to southwest Iowa where 7 plus inches of rain was fairly common (See Figure 5). From the 23rd to the 27th, a statewide average precipitation of 1.56 inches was the wettest period throughout the month of May. Even with the persistent rainy pattern during the month, Iowa remained below normal precipitation for the year (See Figure 6).

may2015precipDFM Figure 3: Accumulated precipitation departure from mean for the month of May 2015.

may2015precipPOM Figure 4: Accumulated precipitation percent of mean for the month of May 2015.

iowa_mrms_q3_monthMay Figure 5: Radar estimated total precipitation throughout the month of May 2015.

Figure 6: Year-to-Date (ending May 31, 2015) accumulated precipitation departure from mean. Figure 6: Year-to-Date (ending May 31, 2015) accumulated precipitation departure from mean.

Several statistics were courtesy of Iowa State Climatologist Harry Hillaker:
http://www.iowaagriculture.gov/climatology/weatherSummaries/2015/pms201505.pdf

Blog post by Kenny Podrazik – NWS Des Moines

Just Another ‘Near Normal’ April 2015

Temperatures

The statewide average temperature for the month of April 2015 was 50.8°F which was 1.9°F above normal (See Figures 1 and 2). April 2015 now ranks as 38th warmest out of 143 years of records. Well above normal temperatures affected the state on the 1st of the month, placing high temperatures across the western two-thirds of Iowa into the 80s (See Figure 3). Temperatures throughout the rest of the month were up-and-down resulting in near normal temperatures (See Figures 4 & 5). Hence, the very warm first of the month added at least an additional 0.5°F onto the monthly average for April (See Figure 6). A brief cold snap occurred on the 3rd and 4th with another extended cold snap lasting from the 20th to the 27th. In between these two cold snaps were a couple of weeks of near to slightly above normal temperatures for central Iowa. During the second cold snap, several locations received a hard freeze on the 22nd and 23rd when low temperatures dropped into the 20s. The warmest temperature in April for the state was 88°F in Little Sioux on the 1st and then 3 days later on the 4th, the coldest temperature in Iowa of 19°F occurred in Elkader and Belle Plaine, Iowa. The most significant temperature gradient across the state set up on April 9th, when highs rose into the middle 80s over southeast Iowa and the northwest portion of the state remained in the lower 40s (See Figures 7 & 8).

Figure 1: Average temperature for the month of April 2015 across Iowa. Figure 1: Iowa average temperature for April 2015.

Figure 2: Average temperature departure from mean for the month of April 2015 across Iowa. Figure 2: Iowa average temperature departure from mean for April 2015.

Figure 3: Average temperature departure from mean for April 1, 2015. Figure 3: April 1, 2015 average temperature departure from normal.

Figure 4: Temperature trend graph for Des Moines during April 2015 shows the wide range of temperatures throughout the month.

Figure 4: Temperature trend graph for Des Moines during April 2015 shows the wide range of temperatures throughout the month.

Figure 5: Temperature trend graph for Waterloo during April 2015 shows the wide range of temperatures throughout the month.

Figure 5: Temperature trend graph for Waterloo during April 2015 shows the wide range of temperatures throughout the month.

Figure 6: Average temperature departure from mean from April 2 to 30, 2015. Compared to Figure 1, April 1st resulted in a significant increase in the monthly average temperature. Figure 6: Average temperature departure from mean from April 2 to 30, 2015. Compared to Figure 1, April 1st resulted in a significant increase in the monthly average temperature.

Figure 7: Average maximum temperature on April 9, 2015 ranged in the lower to middle 80s in southeast Iowa to the lower 40s over the northwest. Figure 7: Average maximum temperature on April 9, 2015 ranged in the lower to middle 80s in southeast Iowa to the lower 40s over the northwest.

Figure 8: Average maximum temperature departure from mean on April 9, 2015 showed the sharp gradient in temperatures across Iowa. Figure 8: Average maximum temperature departure from mean on April 9, 2015 showed the sharp gradient in temperatures across Iowa.

Precipitation

The statewide average precipitation totaled 3.39 inches which was 0.12 inches above normal (See Figures 9 & 10). This resulted in the 49th wettest April among 143 years of statewide climatological records. The highest monthly total at any location was 6.88 inches in Lake Mills, Iowa while the lowest monthly total was 1.18 inches at Rock Valley. The most active periods for precipitation were from the 7th and 9th, from the 18th to 20th, and 24th to 25th. There were a few severe weather events throughout the month, with the most significant event occurring on the 9th when two tornadoes touched down in east-central Iowa. In fact, the 9th had a multitude of different weather; from fog in the morning to severe weather in the southeast to snow over the northwest portions of the state (See Figure 11). In Schleswig, Iowa, 4 inches of snow was reported as a band of 1 to 4 inches set up of west-central to northwest Iowa (See Figure 12). Additional severe weather events materialized on the 7th, 8th, and 18th of the month over portions of southern Iowa.

The statewide average snowfall was just 0.3 inches for the month while the normal for April is 1.6 inches. The seasonal snowfall total now sits at 26.6 inches which is 5.6 inches below the average. April 2015 ranks as the 47th lowest seasonal snowfall total among 128 years of snowfall records for the state. In fact, there have been only 4 years (since snowfall records began at Des Moines in 1884) when Des Moines recorded no measurable snow (greater than a trace) during the entire months of March and April. The 4 years include 1889, 1908, 1981, and 2015. Des Moines last trace of snow in 2015 occurred on March 5.

Figure 9: Accumulated precipitation for the month of April 2015. Figure 9: Accumulated precipitation for the month of April 2015.

Figure 10: Accumulated precipitation departure from normal during April 2015.

IowaSpringWeatherApril 9-2015Figure 11: This graphic shows the various weather across Iowa on April 9, 2015.

Figure 12: Visible satellite imagery showing the 1 to 4 inch snow band that fell over west-central to north-central Iowa on April 9, 2015.Figure 12: Visible satellite imagery showing the 1 to 4 inch snow band that fell over west-central to north-central Iowa on April 9, 2015.

Visible Satellite image on April 9, 2015 depicts the ling of strong to severe thunderstorms developing over southeast Iowa and northern Missouri.

Visible Satellite image on April 9, 2015 depicts the ling of strong to severe thunderstorms developing over southeast Iowa and northern Missouri.

The statewide statistics and a few other statistics were courtesy of Iowa State Climatologist Harry Hillaker and you can find a more extensive statewide summary here: http://www.iowaagriculture.gov/climatology/weatherSummaries/2015/pms201504.pdf

Blog post by Kenny Podrazik – NWS Des Moines

A Very Dry March 2015

Temperatures

For March 2015, the statewide average temperature for Iowa was 36.8°F which was 0.9°F above normal and becomes the 53rd warmest March on record out of 143 years of statewide climatological records (See Figure 1). In fact, a sharp gradient set up across Iowa for the month of March where the northwest ended up being 2°F below normal while the far eastern edges of the state averaged 5°F above normal (See Figure 2). A temperature swing from -17°F to 90°F was the 4th largest temperature extreme for the state. The 3 prior Marches with larger temperature swings were in 1943, 1959, and 1962.

The very cold stretch to end February continued into the first week of March with the first 6 days below normal for the state (See Figure 3). Northern and eastern portions of Iowa recorded minimum temperatures below zero, at least once, during the aforementioned stretch. The coldest day of the month came on the 5th (See Figure 4). For stations within the Des Moines CWA (County Warning Area), the coldest maximum temperature on the 5th was 11°F at Waterloo while the lowest temperature was -14°F at Grundy Center. However, for much of the state, minimum temperatures were 25 to 30 degrees below normal on March 5th (See Figure 5). For the state, the coldest temperature of the month was -17°F on the 5th in Stanley (Buchanan County). Temperatures quickly rebounded across Iowa beginning on the 7th and the warm or above normal pattern persisted through the 22nd. The hottest day of the month occurred on the 16th when much of the state rose well into the 70s and 80s for maximum temperatures (See Figure 6). Des Moines International Airport topped out at 84°F but the hottest temperature on the 16th was 90°F in Sioux City, Iowa. In fact, this is the earliest 90°F temperature reading (calendar year) in Iowa, shattering the previous record by 6 days. The old record was 92°F at Clarinda on March 22, 1910. The second cold snap occurred from the 23rd through the 28th (See Figure 7), even though northeast Iowa was below normal for average temperatures on the 22nd, the statewide average ended up just above normal for the 22nd. The last couple days of March warmed back to above normal to end the month.

March2015AvgTempFigure 1: Average temperature across Iowa for March 2015.

March2015AvgTempDFMFigure 2: Average temperature departure from mean in Iowa for March 2015.

March1-6_2015-DFMTempsFigure 3: Average temperature departure from mean from March 1 to March 6, 2015.

March5-AvgMinTempFigure 4: Average minimum temperature for March 5, 2015.

March5-AvgMinTempDFMFigure 5: Average minimum temperature departure from mean for March 2015.

March16-2015AvgHighTempFigure 6: Average maximum temperature across Iowa for March 2015.

March23-28_2015-DFMavgTempFigure 7: Average temperature departure from mean from March 23 to 28, 2015.

Precipitation

A very dry March for Iowa in 2015 as the statewide average precipitation was a mere 0.59 inches or 1.56 inches below normal (See Figures 8 and 9). March 2015 becomes the 7th driest March out of 143 years of statewide records. If fact, much of the region remained dry and recorded top 10 driest Marches on record (See Figure 10). The statewide average snowfall was 0.9 inches which is 3.8 inches below normal (4.7 inches) for March. Not since 1994 that Iowa had a lower statewide average snowfall for the month of March and 2015 now ranks 9th lowest among 128 years of snowfall records.

Some light snow flurries or snow showers periodically fell over portions of the state between the 1st and the 4th, but the bulk of what little precipitation that did accumulate occurred between the 22nd and 24th of the month. A very dry period from March 4th to March 21st occurred across the state. During this time frame, the statewide average precipitation was only 0.01 inches (See Figure 11) resulting in some fire weather concerns during the middle of the month when temperatures were well above normal. In fact, Des Moines and Waterloo crept into the top 10 driest Marches for their respective stations (See Tables 1 and 2). Precipitation fell in the form of snow or freezing rain across portions of north-central to northeast Iowa as several shortwaves tracked over this area between the 22nd and 24th. Widespread heavy rain fell over the state on the 24th (See Figure 12). The highest amount was 1.32 inches in New Market (Taylor County) and the highest snowfall amount was 12.5 eight miles east-northeast of Decorah on the 22nd.

Figure 8: Average accumulated precipitation departure from mean from March 2015. Figure 8: Average accumulated precipitation departure from mean from March 2015.

Figure 9: Accumulated precipitation March 2015. Figure 9: Accumulated precipitation March 2015.

Figure 10: March 2015 precipitation total ranks by Climate District. Image is Courtesy of Iowa Environmental Mesonet. Figure 10: March 2015 precipitation total ranks by Climate District. Image is Courtesy of Iowa Environmental Mesonet.

Figure 11: March 4 to 21, 2015 accumulated precipitation shows how sparse precipitation was during the middle portion of the month. Figure 11: March 4 to 21, 2015 accumulated precipitation shows how sparse precipitation was during the middle portion of the month.

Figure 12: March 21, 2015 observed precipitation was the most widespread rainfall for the month. Figure 12: March 21, 2015 observed precipitation was the most widespread rainfall for the month.

Des Moines PrecipTop10DryMarch Table 1: Top 10 Driest Marches for Des Moines, Iowa since 1878. 2015 ranks 10th driest March.

WaterlooPrecipTop10DryMarch Table 2: Top 10 Driest Marches for Waterloo, Iowa since 1895. 2015 ranks 9th overall driest.

Statewide climate statistics are courtesy of Iowa State Climatologist Harry Hillaker: http://www.iowaagriculture.gov/climatology/weatherSummaries/2015/pms201503.pdf

Blog post by Kenny Podrazik – NWS Des Moines