A relatively dry pattern has established itself across much of the Upper Mississippi River Valley region over the past 3 weeks, which looks to persist at least into Thursday. As this stretch of dry weather continues through the normally hottest time of the year, more stress is put on vegetation if not watered.
This is a big change from May and June when much of the region was wet. Many locations saw record amounts of rain during these months.
The switch to the drier pattern is a result of the region now more under the influence of high pressure, versus numerous low pressure systems that moved through the area during May and June.
Below are graphs showing how much precipitation has accumulated at La Crosse, WI and Rochester, MN between May 1 and July 14, compared to last year (pink) and the normal amount (brown) for that period. Notice that there has been little accumulation since June 25th, allowing the normal amount to start catching up.
Click the images below for a larger size.