Midwest Weekly Highlights - October 22-31, 2009
Not as Cold, but Very Wet
While temperatures moderated the last ten days of the month, several storms systems dropped copious amounts of rain across much of the region, making this one of the wettest Octobers on record for many locations.
It was still cooler than normal across the western half of the region, with temperatures ranging from 1°F below normal near the Mississippi River to 5 °F below normal over western Iowa. To the east, temperatures reached 2°F to 4 °F above normal in Indiana and Ohio (Figure 1). There were only a few temperature records set during the last ten days of the month, all of them on October 24.
Frequent and occasionally heavy rain brought harvest activities to a halt across much of the region. Precipitation the last ten days of the month was two to four times normal across much of the central Midwest, with a band of precipitation from 500 to more than 600 percent of normal from southeastern Missouri to southern lower Michigan (Figure 2). The only two areas to have near normal precipitation were extreme eastern Kentucky and far northwestern Minnesota. The storms and accompanying rainfall this week resulted in 192 locations in the Midwest setting new monthly precipitation records. The rain also brought further improvement to the drought conditions in the northern Midwest (Figure 3).
A Train of Storms
Rain spread across's all of the Midwest except for the northern half of Minnesota on October 22-23 as a strong low pressure system moved from eastern Kansas on October 22 to northern Illinois on the morning of October 23 (Figure 4). This storm dropped a band of 2.00 to more than 3.50 inches of rain from southeastern Missouri into northeastern Illinois (Figure 5). Flash flooding was reported in Missouri and Illinois as saturated soils had no capacity to absorb the rain.
As the storm lifted out to the northeast and pulled cold air southward snow developed from northern Iowa across northern Wisconsin into the Michigan Upper Peninsula. One to five inches of snow accumulated by dawn on October 24 (Figure 6), with the highest amounts from Phillips, WI (Price County) to Ironwood, MI (Gogebic County). Heavy wet snow accumulating on the remaining leaves on tree branches caused them to break and take down power lines. Widespread power outages were reported in western Wisconsin as a result of the snow.
A day of dry weather followed the departure of this storm, but late on October 25 more showers moved into western portions of the region as another cold front pushed through the Midwest. An upper level low swinging out of the southern Plains on October 27 (Figure 7) interacted with Gulf moisture, spreading a shield of moderate to heavy rain northward into Missouri and eastward across the southern halves of Illinois and Indiana, and south through Kentucky (Figure 8).
There was little respite from the rain, especially for the southern half of the region . A major storm in the southern Rockies on October 28 (Figure 9) took aim on the Midwest only a day after the previous storm's departure. An ample supply of moist Gulf air was expected to feed this system, and flash flood watches were issued from the Gulf coast into the southern half of Illinois on October 29 (Figure 10). Rain developed across the southern half of the region by the afternoon of October 29 and continued on eastward. The heavy rain closed schools early in eastern Missouri, and in St Charles, MO fire officials evacuated two apartment buildings because water had submerged two underground power transformers. The rain ended from Illinois westward by the afternoon of October 30, but continued in the eastern half of the region on October 31. The last of the rain exited southeastern Ohio in the early evening hours of October 31 (Figure 11).
Rainfall amounts from this last storm were heaviest from southeastern Missouri into western Illinois (Figure 12) and also over western Kentucky (Figure 13). In Missouri, Shannon County received more than five inches of rain from this system (Figure 14), and that was on top of 3.50 to 4.00 inches from the storm on October 22-23. Oregon County MO received 4.00 to 5.00 inches of rain. A CoCoRaHS observer north of Winona, MO (Shannon County) measured 10.34 inches of rain October 22-31, and 17.15 inches for the month of October. Average October rainfall is 2.96 inches. Poplar Bluff, MO (Butler County) received 7.11 inches of rain for this period and 15.32 inches for the month.
Midwest Rivers Rise
With the ground already saturated in many areas, the rain this week spilled into rivers and streams. Many rivers in the central Midwest rose to flood levels by the end of the month, and were expected to continue to rise into the first week of November (Figure 15). Moderate to major flooding was forecast for a number of rivers in Missouri and Illinois.
Rain Shuts Down Fall Harvest
With only a day to a day and a half between precipitation events, farmers in the Midwest were not able to make any significant progress in harvesting corn and soybeans. Harvest progress at the end of October was well behind normal in most of the Midwest, not only due to the recent wet weather but also to the general delay in crop progress throughout the season (Figure 16). The exception was in Kentucky, where corn harvest is complete. Many fields were left with standing water after the storms this week and it will take a number of days of sunny, dry, and mild weather before field work can resume.