August 1-6, 2002: A Hot Stormy Start for August.

August began as July ended, with severe weather and heavy rain in the northern tier of the Midwest. The precipitation totals for August 1 to 6 indicate that 1-3 inches of rain fell in eastern Minnesota, northwestern Wisconsin, and northern and western Michigan (Figure 5). The biggest rains, however, fell in the northwestern quadrant of Iowa due to two consecutive nights of training thunderstorms on August 3-4 and August 4-5. Totals over 3 inches were common, with many places receiving 4-6 inches of rain. The southern half of the Midwest, on the other hand, did not receive much rain, with less than 50% of normal levels common in southern Iowa, Missouri, Illinois, Indiana, Ohio, and Kentucky (Figure 6). The period started with a blistering heat wave, but cooled off considerably on the 6th after a strong Canadian cold front penetrated southward to the edges of the Midwest. The average temperatures for the period were still 6-8°F above normal in the southern half of the Midwest, but were cooler than normal by a few degrees in the northwestern Midwest, where the cold air arrived by the 4th (Figure 7). The rain in northwestern Iowa and western Michigan did help alleviate dryness in both areas, but the lack of rain elsewhere in the central and southern Midwest allowed dryness to expand in Kentucky and Ohio (Figure 8, NDMC).

Some of the hottest weather of the summer was felt in the central and southern Midwest from August 2-4. Heat warnings were issued in several of the larger cities, including Kansas City, St. Louis, and Cincinnati. On the 4th, high temperatures reached near 100°F in the southern Midwest (Figure 9), and, combined with dew points in the 70s, experienced heat index values between 105 and 110. Fortunately, only one heat-related death was found in the 3 cities, which each opened cooling centers and activated emergency plans that probably saved some lives.

Strong storms raked across the Upper Peninsula of Michigan on August 1 (Figure 10, National Weather Service - NWS), eventually turning and advancing southward with a cold front through Lower Michigan. The convective rain was especially heavy downwind of Lake Michigan (Figure 11, NWS), relieving drought conditions. The front stalled across the region just north of center. Large complexes of storms developed in Minnesota and northern Iowa several times between the 3rd and the 5th, resulting in a large precipitation totals in northwestern Iowa and southeastern Minnesota (Figure 12, NWS). Finally, on the 5th, the cold front plowed southward vigorously, causing wind damage and power outages in Cincinnati and St. Louis, but otherwise causing no deaths nor widespread damage to buildings. Some crop damage was reported due to hail and straight line winds.