Preliminary Weather SummaryWritten by Theresa Rose on May 21, 2019
Preliminary Weather Summary
Provided by Justin Glisan, Ph.D., State Climatologist, Iowa Department of Agriculture and Land Stewardship
Wetter than average conditions continued across much of Iowa with the state’s western extent experiencing drier than normal conditions. Temperatures across the western half of Iowa were slightly warmer than average while the rest of the state was near or slightly below normal. Cooler conditions in eastern Iowa were partially attributed to increased cloud cover and rainfall.
Rain showers associated with a weak low pressure system dissipated late in the day on Sunday (12th). Daytime highs were in the low to mid 50s; highs in southeastern Iowa were generally 15 to 20 degrees cooler than average. Burlington (Des Moines County) observed a daytime high of 47 degrees, 25 degrees below average. Rainfall was generally confined to southern Iowa where totals reported at 7:00 am on Monday (13th) ranged from 0.05 inches in Keokuk (Lee County) to 0.38 inches in Bedford (Taylor County). Daytime temperatures were boosted into the mid 60s, ahead of an expected warming trend across Iowa.
A fast moving complex of showers and thunderstorms moved from northwestern Iowa though southeastern Iowa on Tuesday (14th) leaving behind above average totals in central and southeastern Iowa, ranging from 0.20 to 0.40 inches above climatological expectation. Boone (Boone County) reported 0.63 inches of rain, 0.50 inches above normal. Wednesday (15th) saw morning fog burn off into sunny and warm conditions. Highs reached into the upper 70s and low 80s in western Iowa and remained unseasonably warm overnight. Stations in Cass, Harrison and Montgomery counties observed 82 degrees, nine degrees above average.
Thursday (16th) began a multi-day stretch of thunderstorms and locally heavy rainfall across Iowa. A warm and unstable atmosphere over central Iowa supported severe storms Thursday night. There were multiple reports of large hail, the largest of which was 1.75 inches in Tama County. Severe straight-line winds were also reported from Dallas to Clinton counties. Overall, this was the most widespread severe weather event so far in 2019, with 11 counties affected. Widespread thunderstorm activity occurred Friday (17th) and Saturday (18th) and was associated with a strong low pressure system. Northern and eastern Iowa received multiple waves of showers and thunderstorms with New Hampton (Chickasaw County) observing the highest 24-hour total of 4.25 inches on the 18th, 4.09 inches above average. Three-day rain totals reported at 7:00 am on Sunday (19th) were above one inch at 48 stations. Temperatures remained mild over the weekend with highs 8 to 12 degrees above average in southern Iowa.
Weekly rainfall totals ranged from 0.11 inches in Mapleton (Monona County) to 4.95 inches in Elma (Howard County). The statewide weekly average precipitation was 1.77 inches, 0.72 inches above average. Temperatures also averaged 61.9 degrees, slightly above the climatological normal of 61.5 degrees. The week’s high temperature of 94 degrees was observed at Clarinda (Page County) on the 16th, 21 degrees warmer than average. Chariton (Lucas County) reported the week’s low temperature of 30 degrees on the 13th, 16 degrees below average.