Sweltering conditions blanketed the state on multiple days during the reporting period as dewpoint temperatures soared into the 70 to low 80-degree range. The statewide average temperature was 76.9 degrees, 6.2 degrees above normal. Showers and a few severe thunderstorms brought rainfall to most of the state's rain gauges with isolated pockets of two to three inches of above-average totals in central and north-central Iowa. Stations in the northwest and southeast observed deficits of up to two inches.
Thundershowers dissipated in eastern Iowa before noon on Sunday (12th) as clouds cleared across the state. Sunshine and a shifting southerly wind boosted afternoon temperatures into the 90s in western Iowa while mid to upper 80s were observed at the remaining reporting stations. Cloud cover increased as a disturbance approached Iowa from the west, producing a strong cluster of thunderstorms over northwestern Iowa prior to sunrise on Monday (13th). Five stations in Lyon County measured at least an inch, ranging from 1.26 inches at Larchwood to 2.00 inches in Rock Rapids. A few severe thunderstorms fired in northeastern Iowa later in the morning as a shield of moderate rainfall spread to the Iowa-Wisconsin border. Stations from north-central to eastern Iowa reported 0.25 -- 0.75 inch in their gauges with 1.25 inches falling at Cresco (Winneshiek County). Afternoon conditions were unseasonably hot with temperatures rocketing into the mid to upper 90s south of a warm front, signaling a stretch of heat and humidity. Clouds pushed out of Iowa overnight as southerly winds picked up through Tuesday (14th) afternoon. Hazy conditions developed as wildfire smoke from Kansas filtered in ahead of a cold front with afternoon highs in the mid to upper 90s over much of Iowa; the statewide average high was 94 degrees, 13 degrees above normal. Heat and instability fueled strong to severe thunderstorms from southwest to central Iowa during the late evening hours. Ample atmospheric moisture produced heavy downpours in numerous cells leaving behind a narrow swath of flooded fields and streets across multiple counties. Thirty-five stations reported at least 2.00 inches with nine gauges in Story County measuring more than 3.00 inches; the National Weather Service co-op station in Story City (Story County) observed 4.60 inches. Rain was observed in Iowa's northwestern half with a statewide average rainfall of 0.60 inch. Hail and high wind damage was also reported over Pottawattamie and Cass counties.
Thunderstorms continued to track over northern Iowa on Wednesday (15th) morning before dissipating after moving across the Minnesota border. Thunderstorms refired in eastern Iowa through the late afternoon and evening hours with multiple severe and tornado-warned cells racing east. Severe straight-line winds reports occurred from Muscatine (Muscatine County) to Mason City (Floyd County) along with a handful of 2.75-inch hail reports in Buchanan County. The line pushed out of southeastern Iowa just after midnight on Thursday (16th) with clearing skies and temperatures in the low to mid 60s. Rain totals from the previous day were highest across a swath of north-central Iowa where several stations reported over 1.50 inches with 2.03 inches in Dakota City (Humboldt County). Moderate rainfall was also observed in southeastern Iowa with many stations measuring at least 0.50 inch. Afternoon temperatures reached into the upper 80s north to low 90s southwest. Isolated thunderstorms fired in extreme southwestern Iowa just after sunset and skirted the Iowa-Missouri border early into Friday (17th). Totals were generally a few tenths of an inch though a handful of stations in Appanoose and Wayne counties picked up from 1.01 to 1.30 inches. Sunshine and variable winds persisted through the afternoon with 80s returning. Southeasterly winds returned on Saturday (18th) along with 90s in western Iowa under a cloudless sky. Spotty clouds moved into central Iowa overnight into Sunday (19th) with balmy morning temperatures ranging from the low 70s northwest to the upper 50s southeast.
Weekly precipitation totals ranged from no accumulation at several south-central stations to 4.70 inches at Story City. The statewide weekly average precipitation was 0.84 inch while the normal is 1.36 inches. Little Sioux (Harrison County) reported the week's high temperature of 102 degrees on the 13th, 19 degrees above normal. Bellevue Lock and Dam (Jackson County) reported the week's low temperature of 51 degrees on the 19th, nine degrees below normal.
Categories: Iowa, Weather