Midwest Overview - April 1-8, 2003

The first eight days of April were quite eventful in the Midwest. Conditions varied from warm and humid with severe convective storms to cold and icy with major winter storms. The turbulent weather did bring some useful amounts of precipitation for some dry areas of the region, including more than 1.5 inches of water equivalent from Chicago eastward to Cleveland and northward into much of Lower Michigan (Figure 1). Southeastern Missouri and Kentucky also received more rain than normal, staving off incipient drought in that area (Figure 2). Only central Minnesota and Wisconsin, and central Indiana really missed out on precipitation this week. For much of the week, a quasi-stationary boundary separated the northern three states of the region from the rest of the region. Temperatures were 6-10°F below normal in northern Wisconsin and Michigan, and 2-6°F above normal in the southern third of the Midwest (Figure 3). The distribution of precipitation helped to ameliorate drought conditions in northeastern Illinois, northern Indiana and Ohio, and much of lower Michigan (Figure 4).

During the April 1-8 period, two major winter storms affected the region, bringing 6-10 inches of snow to areas of northern Iowa, southern Minnesota, Wisconsin and northern Michigan (Figure 5). On April 4-5, the first strong low pressure center moved eastward along a stationary front (Figure 6, U of Illinois Department of Atmospheric Science). On the afternoon of the 4th, severe weather broke out in the warm sector of the system, with small bow echoes and clusters of super cell thunderstorms stretching from Missouri to Ohio (Figure 7, NWS). Tornadoes were spotted in Illinois and Indiana, but did not cause much damage. However, straight line winds exceeding 70 mph heavily damaged or destroyed several mobile homes and a small apartment building in Lincoln, IL, near the central Illinois NWS office. The winds also cut power to 6,600 and knocked down the 911 emergency communication tower for that area. The rotation in that particular storm was well idenitified in NEXRAD doppler radar reflectivity (Figure 8a, UI DAS) and storm relative velocity (Figure 8b, UI DAS)Most of the 200 or more severe weather sightings were for severe hail and wind in the central Midwest (Figure 9), Storm Prediction Center).

The snow on April 4-5 (Figure 10), while causing some transportation problems, was accompanied by substantial freezing rain exceeding 0.5 inches of accumulation in much of southern Michigan. Consumers Energy reported 173,000 customers without power on the 5th in southwestern and south-central Lower Michigan, while Detroit Edison had more than 370,000 without power in their area of service in southeastern Lower Michigan. Northern Oakland County northwest of Detroit was the location of most of the damage. The total of more than half a million without power made this the worst ice storm in Michigan in 27 years, and will lead to very substantial economic costs. In the Detroit Edison area alone, more than 3000 separate power line failures occurred over 44 miles of service lines. Winds made the situation worse, flexing heavily weighted lines and tree limbs until they failed. Five people died in Michigan due to direct effects of the storm, including carbon monoxide poisoning from back-up power generators, falling limbs, and accidents. About 185,000 in Michigan were still without power on April 7, 3 days later. Parts of eastern Wisconsin also had some icing, leading to power outages for about 11,000 and one traffic death on slick roads.

The second snow storm on April 7-8 brought another large dose of snow to the same zone, as another low moved along the stationary front (Figure 11). Up to 10 inches of snow fell in southern Wisconsin, where two died in a snow-related traffic fatality. One man in southern Minnesota died of a snow removal heart attack. Both the Chicago Cubs and the Cleveland Indians baseball home openers were postponed due to several inches of snow on the field. The addition 4-5 inches of snow in southern Michigan slowed progress on power restoration efforts, and caused additional outages due to tree limbs and power lines still burdened with ice being exposed to more snow weight and winds. About 25,000 more customers experienced power outages with the April 7 snow in southeastern Michigan.