The latest Iowa Drought Monitor shows moderate drought conditions have returned to 4.4% of the state, with the rest of Iowa rated as abnormally dry.
Just over half of Fremont County in southwest Iowa is considered to be in moderate drought, along with five counties in the northeast corner of the state. All of Clayton County and most of Fayette County is in moderate drought, along with the northern tip of Dubuque County and southern areas of Winneshiek and Allamakee Counties. The Iowa Drought Monitor is released weekly, on Thursdays, using weather data collected through 8 a.m. Tuesday morning.
During an interview with Radio Iowa early this afternoon, State Climatologist Justin Glisan said rain is in the forecast for the next several days, but Iowa has been abnormally dry this month. “Going back to 1895, when the federal records starts, this is the second driest September through the 18th,” Glisan said. “If you look at the statewide average right now, we’re about at a tenth of an inch and that’s about 5% of normal…In the forecast we do see the potential of an inch and a half to two inches across much of the state with the potential for thunderstorms tonight, but widespread rainfall over the weekend.”
Warm temperatures this month have depleted some moisture in the top soil and, if that isn’t replenished before the ground freezes, it will be a concern heading into spring planting, however Glisan said it’s not a concern right now during harvest season. “Basically the crop is done, so it’s not using a lot of water,” Glisan said. “Stream flows are still near normal or slightly above.”
The storm front that’s moved into the state today is displacing the large ridge of high pressure that prevented thunderstorms from forming.
“Now we’re starting to shift that ridge further east and we’re going to have a low pressure system across the upper Midwest swing a cold front through the state and that’s where you get lift and instability to go along with the moisture that we have readily available,” Glisan said, “and that’s where we’re going to fire thunderstorms off.”
A line of storms stretching from Minnesota, through Iowa and down to Missouri will develop tonight that could be capable of producing large hail. There is the potential for isolated tornadoes as well. Glisan said the longer term weather outlook is for near normal rainfall in Iowa through the end of September.