July 25-31, 2005
Midwest Weekly Highlights - July 25-31, 2005
Wisconsin Drought Relief, Missouri Drought Intensification
The last week of July started with the heaviest rain to hit the region since Hurricane Dennis. On the 25th and 26th, a series of disturbances moved along a boundary between hot and humid air to the south and cooler, drier air to the north. The first band of heavy precipitation extended across southern Minnesota and south-central Wisconsin, and the second band of rain brought precipitation across northern Illinois, Indiana, and Ohio (Figure 1). These two tracks received 150-300% of normal precipitation for July 25-31, while dry areas in Missouri and central and southern Illinois received 50-75% of normal (Figure 2). The second batch of rain was associated with the movement of a cold front through the region, leaving air temperatures 1-3°F below normal in the western Midwest, 1-3°F above normal in the Ohio Valley, and near normal elsewhere (Figure 3). This allowed for a full recovery from the previous week's heat wave. The rain and lower temperatures arrested the deterioration of conditions in the northern Illinois drought core, but were insufficient to show improvement except in an area south of Chicago. Wisconsin, Michigan, Indiana, and Ohio all showed some improvement, too. Unfortunately, conditions did deteriorate further in Missouri, leading to a major expansion of the area labeled as being in extreme drought in the U.S. Drought Monitor map (red area in Figure 4, National Drought Mitigation Center). The last four days of the period were completely dry in the drought region, so some of the recent improvements in conditions were beginning to slowly reverse as the month ended. The federal Department of Agriculture declared a state of disaster for agriculture in Illinois on July 27, 2005, and this made farmers in all but one county (Alexander County in far southwestern Illinois) eligible for emergency low-interest loans.
Limited Relief from Severe Storms and Frontal Passage
More than 48 hours of severe weather and heavy precipitation commenced at the start of the period. A low pressure center moved east from the South Dakota/ Nebraska border, bringing heavy rain to southwestern Minnesota and northwestern Iowa, with some narrow bands of heavy rain further east associated with strong thunderstorm clusters (Figure 5, University Corporation for Atmospheric Research - UCAR). The bow echo in Ohio was especially significant, yielding dozens of reports of severe winds and wind damage (Figure 6, Storm Prediction Center - SPC). Nearly 10,000 in northwest Ohio, 30,000 customers in northeastern Ohio, and 24,000 in greater Cincinnati lost power for several hours or more in the midst of continuing high heat and humidity. Many trees where knocked down, damaging homes, parked cars, and other buildings, and three planes tied down at Burke Lakefront Airport in northern Ohio were flipped over and heavily damaged. Winds were measured at 75 mph nearby.
The cold front entered the region late on the 25th and early on the 26th (Figure 7, College of DuPage - COD). Dew points ahead of the front were over 70°F everywhere, and above 75°F in places (Figure 8, COD). Strong thunderstorms formed both ahead of the low center along the stationary front, and ahead of the cold front dragging slowly through the Midwest (Figure 9, UCAR). In Wisconsin, where storm after storm passed over the same locations, rainfall totals of 2-4 inches were common, and exceeded 7 inches in one case (Figure 10, National Weather Service - NWS).
After slowing down overnight, severe storms developed during the afternoon and evening on the 26th (Figure 11, UCAR). The Doppler radar velocities of the line of storms in east-central Illinois exceeded 50 knots (bright red areas in Figure 12, COD). Several tornadoes were spawned in neighboring Indiana, including an F-2 tornado in Miami County with a damage path 4 miles long. Considerable structural damage occurred to rural structures. As on the previous day, long lived storms caused dozens of storm reports for this event (Figure 13, SPC). Once again, trees and power lines were down, and some building damage occurred, especially in Indiana. About 50,000 customers lost power in the Lafayette, Noblesville, and Kokomo, IN, areas, and a person was injured by lightning. The Detroit area was also lashed by high winds, resulting in about 25,000 without power. More than 2,500 lightning strikes hit the southeastern Michigan area, starting several house fires, but there were no reported injuries. Unfortunately, two swimmers at the Indiana Dunes National Lakeshore drowned in rough waters stirred up by the windy storm.
Cooler and Drier
The cold front really did bring seasonably cool air to the west and north portions of the region, with record low temperatures of 52°F in Sioux City, IA, and 48°F in Mankato, MN, on July 27; 56°F in Joplin, MO, on July 28; and 36°F at International Falls, MN, on July 29. Many other locations tied previous low temperature records. Rain was restricted during the last few days of July to a narrow band across the northern border of the Midwest states and Canada, with beneficial rains hitting the drought stricken Upper Peninsula of Michigan, but not much else. At the end of the month, a warm front announced the return of warmer than normal and more humid air. Drought conditions in the areas missed by rain worsened as the soybean crop reached the critical time for yield development.