Midwest Overview - June, 2006

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Cool, Generally Dry

The overall weather pattern during June dominated by a persistent trough over the eastern U.S. and a strong ridge in the western U.S. (Figure 1). The resulting northwesterly flow aloft over the Midwest prevented  moisture from the Gulf of Mexico from interacting with the frontal systems and resulted in generally dry weather across the northern Midwest.  Rainfall was more plentiful to the south where frontal systems tended to stall out (Figure 2).  Rainfall ranged from 50 percent or less of normal from northwestern Minnesota through northern Wisconsin and into southwestern Lower Michigan. Rainfall was also well below normal in west-central Iowa, ranging from 50 percent to less than 25 percent of normal. While the dry weather was not good news for farmers, impacts from the dry weather were mitigated somewhat by the fact that this same pattern resulted in cooler than normal weather across the entire region this month and heat stress did not compound the impacts of lack of rain in the dry areas. Temperatures this month were near to below normal across the region, with the coolest area (1°F to 2°F below normal) extending from eastern Iowa southeastward into most of Ohio (Figure 3).  Northern Minnesota and across northwestern Wisconsin, including the eastern Michigan U.P. experienced temperatures near to slightly above normal.

This was a very active month for severe weather with severe weather was reported somewhere in the nine-state Midwest region on 28 of 30 days this month. Numerous smaller upper level disturbances dove through the Midwest in the northwest flow providing opportunities for thunderstorm development.  The largest outbreak was on June 22, when severe weather was widespread in a band from eastern Missouri through Ohio. Most of the severe weather was in the form of damaging winds and hail, although tornadoes touched down in Missouri, Illinois, and Ohio. There were a number of reports of crop damage due to hail throughout the month. Severe weather in Ohio was compounded by flooding caused by five to seven inches of rain in parts of north and north central Ohio. 

The unseasonably cool weather the second week of June was responsible for numerous low maximum temperature records on June 10, and scattered record low temperatures on June 11-12. Temperatures struggled to reach 60°F in southern Minnesota, Iowa, and northwestern Illinois on June 10, and temperatures averaged 15°F to 25°F below normal from southwestern Minnesota to southern Ohio (Figure 4).

The last week of June was largely representative of the first three weeks of the month, with thunderstorms and severe weather almost every day but only spotty rainfall for much of the region, and temperatures near to below normal across the region.

 
[For more details on weather and climate events during June 2006, please click on the individual weekly report links on the upper right.]

SDH