Midwest Weekly Highlights - July 1-7, 2009
July started on a cool and relatively quiet note across the Midwest. Unseasonably cool temperatures spread across the Midwest during the first week of July. A trough of low pressure over the Great Lakes drifted slowly to the East, while counter-clockwise circulation around the system brought in cooler air from Canada (Figure 1). Temperatures across the region ranged from 2°F to 10°F below normal over the entire region (Figure 2). Numerous record for lowest maximum temperature were set across the Midwest this week, with every state in the region setting at least one record (Figure 3).
Precipitation varied widely across the region this week. A surface low crossed the southern portion of the region on July 4th and 5th, raining out fireworks displays across Iowa, Illinois, Missouri, Indiana, Kentucky and Ohio while leaving the northern portion of the region dry. Precipitation was 200 to 300 percent of normal across central Missouri this week, while portions of Minnesota and Wisconsin saw only 2 percent of normal precipitation (Figure 4). The July 7 US Drought Monitor showed an expansion of drought conditions in Minnesota and Wisconsin (Figure 5). Most of Minnesota is now is the Abnormally Dry category, and Severe Drought has expanded across much of northern Wisconsin.