Midwest Weekly Highlights - October 1-7, 2009
Cooler and Wetter
Much cooler than normal weather was the main weather feature the first week of October. Temperatures ranged from 4°F below normal in eastern Ohio to 9°F below normal in extreme western Iowa (Figure 1) . Freezing temperatures have occurred across the northern Midwest, mostly Wisconsin and Michigan. A hard freeze ending the growing season across northern Wisconsin and Michigan on the morning of October 1 as temperatures dropped into the low and mid 20s. The observer at Stambaugh, MI (Iron County) recorded a low temperature of 17°F, a record for the date. Maximum temperatures were as much as 13°F below normal in western Minnesota, and ranged from 4°F to 9°F below normal across the remainder of the region (Figure 2). There were a number of record low maximum and minimum temperatures set in the Midwest the first five days of the month. Persistent cloudiness over the northern Midwest kept minimum temperatures generally above normal during the week. Average daily minimum temperatures across the northern half of Minnesota were 1°F to 3°F above normal, and near normal over southern Minnesota and Wisconsin (Figure 3). Average daily minimum temperatures over the remainder of the region were 1°F to 5°F below normal.
The heaviest precipitation this week occurred in the northwestern half of the region. Precipitation was 500 to 700 percent of normal across the southern half of Minnesota and the northern half of Iowa. In contrast, little precipitation fell in the eastern half of Kentucky (Figure 4). The heavy rain in the upper Midwest did bring some relief to the Severe to Extreme Drought area in the northern half of Wisconsin, and there was a one category improvement across southern Minnesota in the October 6 U.S. Drought Monitor (Figure 5). On October 1 thirty-one counties in Wisconsin were declared to be natural disaster areas by the U.S. Department of Agriculture due to the drought, which has persisted since March. The declaration permits affected farmers, ranchers, and other agricultural producers to apply for low-interest emergency loans from the Farm Service Agency.
Strong Fall Storm in Upper Midwest
As the month began a strong low pressure system was strengthening over the Central and Northern Plains. This storm took almost five days to move through the upper Midwest. Most of the precipitation with this storm fell on October 1 and 2 as the low sat spinning over southern Minnesota (Figure 6). Much of the southern two-thirds of Minnesota received from 1.50 to more than 3.00 inches of rain (Figure 7). In comparison, average rainfall for the entire month of October in Minnesota ranges from 2.00 to 2.75 inches (Figure 8). Rainfall amounts across Wisconsin, were drought has been entrenched since March, were generally 1.50 inches or less with a few locations accumulating around 2.00 inches.
Scattered thunderstorms occurred ahead of the cold front on October 1, with some severe weather reported in southwestern Missouri and one severe storm in Iowa.
Variably cloudy, cool weather persisted over the northern half of the Midwest as the low pressure system moved slowly northeastward. As the storm moved through southern Wisconsin (Figure 9) powerful westerly winds produced gusts topping 50 mph late on October 6. A 63 mph gust was measured at 9:05 p.m. three miles off Chicago's shoreline at the Harrison-Dever Crib. Wind gusts to 40 mph were measured from eastern Iowa south into central Illinois and Indiana.
Rain persisted on October 6 on the back side of the low as it moved to near James Bay in Canada. One and a half to two inches of rain fell from the Michigan Upper Peninsula into northeastern Wisconsin by the morning of October 7 (Figure 10 ).
Next Storm Poised to Hit
Even as the previous storm was moving further into Canada, another storm system (Figure 11) was threatening to spread rain over the southern of the Midwest as the second week of October began.
Agriculture Hoping for Late Freeze
The combination of late planting in parts of the Midwest combined with the unusually cool growing season has put corn development as much as four weeks behind, especially in Illinois, Indiana, Wisconsin, and Michigan. Corn maturity is far behind in these areas (Figure 12), and is vulnerable to damage from an early or even normal freeze. A hard freeze (<=28°F) has already occurred from northeastern Minnesota through the northern two-thirds of Wisconsin and northwestern Michigan (Figure 13).