Heavy Rain in Union County, Iowa

Event total rainfall of 5.11 inches so far. Measured by a personal weather station.

A surface boundary across northwest Iowa in the morning slowly sunk into central Iowa later in the day. By then, daytime heating resulted in sufficient destabilization for for convective development along the boundary. Surface based CAPE of 2000 J/kg was present across central to southern Iowa, though weaker deep layer shear of 25 kts or less prevent better organization of storms. Gusty winds of 60 to 65 mph were observed with storms, especially early on in storm development with dry air in the lowest levels. As deep saturation occurred through the late evening and overnight, the primary hazard of concern transitioned from damaging winds to heavy rain. Repeated heavy rain fell across southern portions of Iowa and deep warm cloud layers allowed for efficient rain production. PWAT values were generally in the 2 to 2.3 range and rain totals through late morning on June 24 were from 4 to 6 inches in a band across southern Iowa with isolated totals of 7 to 8 inches or more. Despite these very high rainfall amounts, very little hydrologic issues were reported. This was likely avoided thanks to rain falling across rural areas with quickly maturing crops able to absorb the heavy rain.