Midwest Weekly Highlights - May 25 - 31, 2007

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The Memorial Day Mix

The final week of May ended with storms and warmer than normal temperatures across the much of the Midwest. The average daily temperature departures across the region were indicative of moderately warmer than normal temperatures. Eastern sections of the Midwest saw their temperatures 4° to 8° F above normal (Figure 1). The warmest state was clearly Ohio where over three quarters of the state was 8° warmer than normal. Minnesota and Iowa were contrasted from the warmer states. The extreme northwest corner of Minnesota saw temperatures 8° below normal while the rest of the state, including the state of Iowa, recorded average daily temperatures slightly below to near normal.

Precipitation struggled to fall across Kentucky, Ohio and sections of Indiana but fell in plentiful, but somewhat widespread, amounts across Missouri, Illinois, Iowa and northern Minnesota. Sections of northern Minnesota and Wisconsin, which have been classified in drought from the Drought Monitor, had much needed relief occur from storms that emanated from the Great Plains. Much of northern Minnesota is no longer classified as category D3 Drought - Extreme (Figure 2). This is in contrast to the previous week (Drought Monitor 05/24/2007) where most of the area was included in the D2 Drought - Severe to D3 Drought - Extreme categories. The southern half of Kentucky failed to see any real precipitation over the last week. Most of the state has only seen 0 to 5% of the normal precipitation for this time period. Southern Ohio, primarily from Columbus south, has seen the same fate as Kentucky with only 0 to 25% of the normal precipitation expansively covering this area (Figure 3). This lack of precipitation and increased temperatures downgraded sections from category D0 - Abnormally Dry to D1 Drought - Moderate. If precipitation fails to fall in early June, further downgrading will be in the works.

High pressure off of the east coast primed the area for the mix of Memorial Day weather. The majority of the surface wind flow was from the south where copious amounts of heat and humidity worked their way into the region. Then an area of surface low pressure formed in the Northern Plains and slowly skirted across Minnesota and Wisconsin through the weekend. A warm front extended from New Jersey to the low in North Dakota early on Saturday, bringing up temperatures across the area. By Sunday the cold front from this low had stalled out across the Great Lakes down through Missouri. During the beginning of the week, Illinois acted as the fulcrum of the hypothetical atmospheric lever (Figure 4). Showers and thunderstorms occurred daily near the vicinity of the fronts. A few isolated tornadoes were reported in Iowa, Minnesota and Wisconsin on May 26th and May 28th. The tornadoes were all preliminarily rated as EF0 or less and damage was minor. As the low and its associated front slowly drift to the East, the hope is that many rain deprived areas finally receive their much needed precipitation.

 

Records for May 25 - 31, 2007

Date	Location	Record Type	New Record	Old Record & Year
May 30	Muskegon, MI	Max	86°	86°/2006

 

MCP/SSS