Midwest Weekly Highlights - June 24-30, 2008
The Rain Returns
Heavy rain hit the flood-ravaged Midwest again this week, sustaining and even increasing water levels on the Mississippi River. The heaviest rain this week fell in Iowa, northern Missouri, and western Illinois. Rainfall was 300 to 500 percent from southern Iowa through northern Missouri and western Illinois (Figure 1). Heavy rain also fell in Ohio, where rain was two to three times normal for the week. Dry weather was found from northern Minnesota across northern Wiconsin and Michigan, and in the lower Ohio Valley.
The week started with a continuation of the cooler than normal weather, but southerly winds brought increasing temperatures and dewpoints by the middle of the period. Average daily temperatures were from 3°F to 4°F below normal in Iowa and Missouri, where overcast skies and heavy rain dominated the early part of the period (Figure 2). Temperatures were near normal to as much as °F above normal in the far northern and eastern portions of the region.
Iowa Soaked Again
What began as a small cluster of thunderstorms over southwestern Iowa and eastern Nebraska during the late afternoon of June 24 was the beginning of the first major rain this week (Figure 3). By 10:00 p.m. CDT a mesoscale convective system (MCS) was moving across southern Iowa and northern Missouri, and by midnight CDT two intense lines of thunderstorms were in progress over northern Missouri (Figure 4). This complex of thunderstorms moved slowly eastward, and training thunderstorms poured more than 8 inches of rain on northern Missouri (Figure 5). Linn County in north-central Missouri was the hardest hit, with the cooperative observer in Linneus, MO reporting 8.61 inches of rain, and the observer southeast of Linneus reporting 7.42 inches. The Missouri Department of Transportation and local law enforcement reported numerous roads closed due to flooding. Rivers in the region experienced rapid rises and there was widespread river flooding.
Further to the east, 3 to 5 inches of rain fell in the Mississippi River valley in eastern Missouri and western Illinois. The excessive rain caused forecasts of Mississippi River levels south of Quincy, IL (Adams County) to be revised, delaying the fall or forecasting secondary crests.
The next round of storms began late in the afternoon of June 25 with a small area of thunderstorms in northern Iowa (Figure 6). This developed into a line of strong to severe thunderstorms which moved south over saturated areas of central and eastern Iowa and western Illinois. By the morning of June 26 the storms had spread south to near St. Louis and back to the west over north-central Missouri (Figure 7), dumping more rain on the areas that had received 5 to 8 inches of rain the night before (Figure 8). Heavy rain was reported in central Iowa on June 26 which resulted in flash flooding. Three to four inches of rain were reported northwest of Des Moines in Polk County, IA in the 24-hour period ending at 7:00 a.m. on June 26.
And Further to the East...
While most attention was focused on the Mississippi River Valley, strong to severe thunderstorms soaked central Ohio with more than 4 inches of rain during the early morning hours of June 26 (Figure 9). Widespread flash flooding occurred in northern Fairfield, Franklin, and Licking counties. Rivers and streams spilled out of their banks into farm fields and roads. in Licking County the heavy rain caused an automated system to trigger and discharge water from the Buckeye Lake spillway to avoid topping the dam. This caused the South Fork of the Licking River to rise 9 feet and flood the adjoining Interstate 70. A three-mile section of Interstate 70 was closed in both directions just north of Buckeye Lake for 15 hours and traffic had to be re-routed. Additional severe storms fired during the afternoon from Indiana eastward through Ohio and north into southern Michigan. The storms resulted in flash flooding in Lorain, Huron, and Stark counties in northern Ohio. Three people had to be rescued from their vehicles in Wellington, OH (Lorain County) when their cars became submerged. In Toledo lightning started a fire that destroyed a strip mall near the University of Toledo. Strong winds downed power lines and trees, knocking out power was to about 10,000 utility customers in northwest Ohio and southeast Michigan.
More Rain in Iowa
A cold front dropping into the northern Midwest provided yet another opportunity for heavy rain to develop. While thunderstorms moved eastward into western Iowa during the early morning hours of June 27, a smaller cluster of thunderstorms began to develop over southeastern Iowa (Figure 10). The storms moved slowly eastward over the next four to six hours, dropping two to four inches of rain on causing flash flooding in Keokuk and Washington counties (Figure 11).
Thunderstorms erupted again in during the afternoon and evening of June 27 as the cold front pushed southeast. Severe storms occurred through most of the region, with the greatest concentration in Iowa, Missouri, and the southern half of Illinois. There were several reports of weak tornadoes in Illinois and Indiana. In Council Bluffs, IA (Pottawattamie County), two people were killed and one was injured when high winds caused a tree to fall on their vehicle. Golf ball to baseball-size hail fell in Madison County, IA during the afternoon. Heavy rain in southwestern Missouri prompted flash flood warnings for Greene, Dallas, Polk, and Webster Counties. The heavy rain also cause a rapid rise in the water level in Lake Taneycomo near Branson, MO early on June 28. Firefighters evacuated a campground and went door-to-door in some neighborhoods in Branson advising residents to consider evacuating. Several motorists and mobile home residents had to be rescued when Turkey Creek surged out of its banks. The flash flooding also caused some damage to roads and flooded parts of Interstate 44.
On June 28 storms were concentrated ahead of the front in Ohio and underneath the strong upper level low pressure system in southern Wisconsin, northern Illinois, and Michigan (Figure 12). Severe storms moving through the Chicago area blew down tents at an Evanston, IL (Cook County) art festival, injuring ten people. A wind gust of 74 mph was reported in DeKalb, IL (DeKalb County). The storms also knocked out power to 28,700 utility customers in the Chicago area.
A Quiet End
A sprawling high pressure system brought quiet weather to the region the last two days of June, with only scattered showers popping up in some areas during the heating of the day. Temperatures were generally below normal for late June, and dew points were back to comfortable levels in the 40s and 50s (Figure 13).
June 30 flood status: Indianapolis
June 30 flood status: St. Louis
On June 27 the southern end of Pin Oaks River Levee was breeched, flooding Winfield, MO. According to the U.S. Army Corps of Engineers, the levee simply sustained water levels higher than it was designed for and for a much longer period of time than anyone had hoped. Officials suspect muskrats tunneling into the levee contributed to the breech.