The statewide monthly average temperature for Iowa in June 2014 was 70.3°F which was 0.6°F above normal. June 2014 ranks 55th warmest June among 141 years of records in the state of Iowa. The average temperature within the NWS Des Moines County Warning Area (DMX CWA) was 70.0°F for June 2014 and the average maximum temperature was 79.8°F and the average minimum temperature was 60.1°F. The DMX CWA is outlined in white in Figures 1-4. Roughly 3 out the 4 weeks in June remained above normal with a cold stretch occurring from June 7 to 13 (See Figure 1).
The coldest temperature across the DMX CWA was 39°F in Emmetsburg on June 9th while the lowest in the state was 38°F at Battle Creek on the 13th. However, much of the departure from normal only ranged about 1 to 5 degrees above normal during the month. In fact, only one day topped 10 degrees above normal, within the DMX CWA, and that occurred on the 1st (See Figure 2). Since no long duration heat wave developed during June, the majority of stations only reach 90°F a couple of times. Des Moines reached exactly 90°F on the 16th, 18th, and 20th while Waterloo’s hottest temperature was only 88°F on the 1st. Typically, Des Moines averages 4.5 days and Waterloo averages 4.1 days with 90°F or greater maximum temperatures during the month of June. The two stations combined for 4. Other ASOS (Automated Surface Observing System) stations such as Lamoni, Ottumwa, Marshalltown, and Mason City never topped 90°F during the month. By the end of the month, Mason City still had not reached 90°F since September 9, 2013 and this streak continued into July.
The statewide monthly average precipitation for June 2014 was 9.94 inches which was a whopping 4.92 inches above normal (See Figures 3 and 4). June 2014 became the 3rd wettest June among 141 years of records and the 4th overall wettest month for Iowa (See Table 1).
Daily precipitation records were set at Mason City, Lamoni, and Waterloo during the month (See Table 2). Waterloo, Iowa had its 3rd highest June precipitation with a total of 9.63” for the month, which was just ahead of the 8.79” total in 2008 (See Figure 5). Most sites across central Iowa reported precipitation for at least two weeks (not consecutively) out of the month of June. For instance, Ottumwa recorded at least a trace of precipitation 19 out of the 30 days in June and 6 days had at least a half inch or more. Des Moines, Waterloo, Lamoni, Estherville, and Marshalltown all had 4 days with 1” or more of precipitation. Ames came in with 5 days with daily totals of 1” or more. All this precipitation led to significant flooding and flash flooding across the DMX CWA during June 2014. The upper Des Moines River and the Cedar River were affected the most as 13 river stations topped flood stage.
A very active severe weather pattern occurred in Iowa during June 2014 with June 3, June 16, and June 30 receiving the most significant and widespread severe weather. On June 16, 9 tornadoes occurred within the DMX CWA, while altogether there were 12 tornadoes in the state. June 29-30, separate systems, but the two-day total for tornadoes was 13 for the state, in which 11 occurred in the DMX CWA. For the entire month, there were 31 tornadoes across the state of Iowa resulting in a total path length of over 107 miles long. The highest rating was EF2 for two tornadoes. The first one occurred on June 3 in Pottawattamie County southeast of Bentley and the second dropped across Tama County northwest of Traer. For more detailed Iowa tornado information, visit our tornado page: http://www.crh.noaa.gov/dmx/?n=iators2014
Tornadoes were not the only severe weather hazards that affected Iowa in June as the aforementioned dates, along with a few other events, produced significant damage from very large hail and damaging winds. On June 3, southwest Iowa was hardest hit with wind-driven hail as it produced significant damage to crops and buildings, where siding was completely shredded off several homes (See Figure 6). June 30 produced similar wind-driven hail that caused major damage across portions of central Iowa and more detailed information the event can be found here: http://www.crh.noaa.gov/dmx/?n=june30event
The Saylorville Reservoir pool height began at 837.84 feet on the 1st and rose over 30 feet to a height of 868.23 feet by the 30th (See Figure 7). The normal pool height is 836 feet. The pool storage monthly maximum was 333,960 Acre-feet on the 30th while the minimum pool storage was 67,068 Acre-feet on the 13th. The Des Moines River downstream of Saylorville Lake fluctuated throughout the month before cresting at 15.25 feet on the 27th with a flow of 19,500 cubic feet per second or CFS (See Figure 8).
Lake Red Rock Reservoir pool height increased from 743.77 feet on the 1st to 752.30 feet by the 30th. The pool storage doubled in volume within two weeks as it rose from a minimum of 189,420 Acre-feet on the 15th to a monthly maximum of 404,370 Acre-feet on the 30th (See Figure 9). The stage height of the Des Moines River downstream of Lake Red Rock Reservoir increased from a low of 86.73 feet on the 1st to a maximum height of 92.50 feet on the 29th. The outflow maxed out at 19,000 CFS on the 28th and 29th while the lowest flow was 3,950 CFS on the 16th.