Accumulated Precipitation - Inches
Average Maximum Temp Departure
Drought Monitor
June 29 Derecho Radar Summary

Midwest Weekly Highlights - June 24-30, 2012

Widespread Below Average Precipitation

Precipitation was minimal across much of the Midwest during the last week of June. Besides two events that brought some precipitation to the upper Midwest and the central Midwest, the rest of the region received little to no precipitation throughout the week (Figure 1). The highest precipitation amounts of 0.75 to 1.5 inches were found in eastern Iowa and western Illinois. A band of precipitation measuring at least 0.5 to 0.75 inches stretched from eastern Iowa to central Ohio. The whole Midwest, with the exception of a small area on the border of Iowa and Illinois, received below average precipitation during the week (Figure 2). The largest negative departures from normal precipitation were found in southern Missouri, southern Illinois, southwest Indiana, and western Kentucky. There were a few precipitation records set throughout the week, with the majority occurring during an event in the central Midwest on June 29th .

Record-Breaking Hot Temperatures

Temperatures were above average across the region during the last week of June (Figure 3). The whole region was at least 1°F above average, except for a small portion of eastern Kentucky, which was near normal. Missouri had the highest departures in the region, with a majority of the state experiencing temperatures that were 7°F to 10°F above normal. Daytime maximum temperatures were unseasonably warm, with southern parts of the region averaging maximum temperatures throughout the week of 95°F to 105°F (Figure 4), which was at least 8°F to 14°F above normal (Figure 5). In contrast to daytime temperatures, overnight temperatures were either near normal or below normal for much of the region (Figure 6). The greatest departures were in eastern Kentucky, where overnight minimum temperatures were 5°F to 6°F below normal. The western Midwest and parts of the upper Midwest experienced above average minimum temperatures.

The unseasonably warm daytime temperatures set or tied several hundred temperature records throughout the week (Figure 7). A majority of the records set were maximum temperatures, but record high minimum temperatures were set as well. Altogether, there were just over 520 daily temperature records set in the region and just over 150 monthly temperature records set. Some locations recorded their highest ever maximum or minimum temperature during the last week of June (all-time records).

Drought Conditions Worsen

The widespread low precipitation during the last week of June exacerbated the already dry conditions in the region. On the latest release of the US Drought Monitor, Extreme Drought (D3) conditions expanded in the southern Midwest and developed in northern Indiana (Figure 8). The regions experiencing extreme drought have only received 25% to 50% of their normal precipitation since April 1, 2012 (Figure 9). According to the Drought Impact Reporter, the extremely dry conditions are severely stressing crops, reducing crop quality, and as a result, a reduction in crop yield is expected in some areas.

Derecho Event - June 29, 2012

On Friday, June 29th, a strong derecho made its way across the eastern Midwest, bringing widespread 60+mph winds to the region (Figure 10). Preliminary reports indicate wind gusts of 90+ mph were recorded in Oswego, Illinois (Kendall County), Fort Wayne, Indiana (Allen County), and Marengo, Iowa (Iowa County). The total path of the derecho event was about 600 miles, stretching from northern Indiana all the way to the Atlantic coast (Figure 11). Across the region, there were several reports of trees and power lines being blown down, damage to buildings, and power outages as a result of the high winds associated with this derecho. To read more about this event, visit the NWS Northern Indiana and NWS Wilmington, OH summaries.


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