September 18-24, 2004
Midwest Weekly Highlights - September 18-24, 2004
Another Tropical Week in the Midwest
The remnants of Hurricane Ivan brought tremendous rains and floods to the far eastern Midwest
on September 17-18. Most of the rain recorded on the weekly map of Midwest precipitation for
September 18-24 (Figure 1) is from Ivan, although there was another distinct area of wetness in
western Minnesota and northwestern Iowa. Both of these sections of the Midwest recorded 2-6
inches of rain, although flooding was more severe in the Ohio Valley due to previous rains from
Frances saturating the ground prior to the arrival of Ivan. In the central two-thirds of the
Midwest, however, it was very dry, with most of the region receiving 0-25% of normal
precipitation for the week (Figure 2). This coincided with a strong ridge of high pressure and
maximum temperatures in the 80s throughout the period (Figure 3), more befitting August than
September. In the northwestern portion of the Midwest, the weekly temperature departures from
normal exceeded +10°F over a broad band, and most of the Midwest was at least +4-8°F above
normal (Figure 4). Only the southeastern Midwest, under Ivan’s shadow, remained near-normal
in temperature. The path of Ivan, the precipitation in the far west, and the warmth in the
Midwest all were the result of a stationary upper level ridge that steered low pressure centers and
cold air to the north of the region and allowed Ivan to approach from the south (Figure 5, Climate
Diagnostic Center).
Ivan the Terrible
Precipitation totals of 3-6 inches fell on September 17-18 in eastern Kentucky and southern and eastern Ohio (Figure 6). Precipitation totals exceeded 4 inches at 13 recording stations in Ohio and 28 recording stations in Kentucky that reported in real time. The low pressure center of the remnants of Ivan traveled north along the spine of the Appalachians (Figure 7, College of DuPage - COD), slinging a huge precipitation shield into the western side of the mountains (Figure 8, COD). Localized flash flooding and small stream flooding occurred in many places in Kentucky and Ohio (Figure 9, US Geological Survey - black dots indicate record flows for the day of year). Unfortunately, copious amounts of rain also fell upstream of Ohio in Pennsylvania and West Virginia, swelling the Ohio River to tremendous levels not seen in many years in some locations. The gauge at Racine Dam, along the Ohio south of Marietta, OH, achieved an all time highest flood level of 50.2 ft (Figure 10, NWS), about 2 feet above the old record. The river at Marietta was also very high, at almost 10 feet above flood stage (Figure 11, NWS).
Conditions in Kentucky and parts of Ohio were actually less severe than forecast, as the remnants of Ivan moved more quickly than expected. This being said, all 33 counties in eastern Kentucky reported flash flooding or stream flooding, and many roads were closed by high water or mud slides. The small town of Salt Lick, KY, was half covered by flood waters, and many isolated homes were also damaged by floods. One person died in eastern Kentucky when they drove into high water and were swept away.
In Ohio, 115 students spent the night in Amesville Elementary, as flood waters surrounded the
school and flooded much of the town. The 126-year old Rinard Covered Bridge on the Little
Muskingum River near Bloomfield was completely destroyed. About 1700 people evacuated
low lands near rivers in the region. The worst flood effects occurred at Marietta, OH, where the
Ohio River rose more quickly than expected, requiring about 40 water rescues of people living in
low lying areas of town. The Muskingum River and Duck Creek had flooded much of downtown
when the precipitation fell, and then water backed into town again as the Ohio River flooded the
next day. Hundreds of people abandoned their flooded homes, and most of downtown was under
several feet of water. About 400 homes and 600 businesses were damaged, some severely.
Town officials installed snow plows on dump trucks to scrape the mud and debris off the city
streets. A federal disaster declaration was issued for 15 counties in eastern Ohio on the 19th
(Figure 12, FEMA). Fortunately, no deaths were ascribed to the flooding in Ohio.
The Heat was Tropical Too
With such unusual steering currents and such a strong ridge (Figure 5, CDC), the heat in the region began to set records towards the end of the week. Green Bay, WI, had 14 days during September with a maximum temperature of 80°F or above through the 23rd, setting an all-time record for the month of September with one week to go. Marquette, MI, set new records of 79°F and 82°F on September 22 and 23, respectively. Alpena, MI, also set a new record on the 22nd of 86°F, and Flint, MI, set a record of 85°F on the 23rd. Minneapolis and Milwaukee NWS forecast offices indicated that temperatures in those cities were lining up to produce a top ten warmest September in both places. Along with the warmth came more reports regarding increasing dryness in the Midwest. Through the 24th, the precipitation deficit since July 1 had reached -5.47 inches at Green Bay,WI, while in much of eastern Wisconsin and western lower Michigan, total rain amounts for September were well below one inch and could also lead to a place within the bottom 10 September precipitation totals. Some of the northern Midwest crops ceased growth this year not because of cool temperatures, but because they ran out of water during this warm and dry September. Even in the core of the Corn Belt, problems were reported in some areas with soybeans drying too fast, leading to problems with shattering. However, the warmth was still a great benefit, allowing many crops to mature that otherwise could have been caught short by an early frost due to the lack of growing degree days in August.
Lack of precipitation will not be a problem under the active jet stream in the far western Minnesota/Iowa region. The town of Spencer, IA, has already set a new record for month of September precipitation total, of 12.44 inches, even though this total includes rain only through the 21st. A number of locations exceeded 2 inches of rain with the system this week. The last week of September seems likely to remain fairly dry, probably resulting in an increase in abnormally dry areas on the U.S. Drought Monitor (Figure 13, National Drought Mitigation Center). The only exception may occur in the far eastern Midwest if Hurricane Jeanne (Figure 14, NWS) becomes the third tropical system to reach the Midwest this month.