September 2000
Temperature and Precipitation Anomalies.
During September, the Midwest received approximately normal amounts of precipitation for the region, ranking as the 50th driest September. Average temperature was slightly on the cool side, with the Midwest having its 34th coolest September (Figure 1). However, there were distinct patterns to both precipitation and temperature departures. As in August, precipitation in September was lacking in Minnesota, Iowa, and Missouri, where less than 75% of normal amounts fell. On the other hand, most of the rest of the Midwest received above normal precipitation, especially Indiana, which had its 20th wettest September in 106 years (Figure 2).
Most of the Midwest was dry and warm over the end of August and the first week of September, due to an extension of the strong high pressure ridge over the southern Plains into the southwest quadrant of the Midwest. Some areas were very dry, especially Missouri, Iowa (except for its northwest division), and Illinois, all receiving less than 0.5 inches of rain. It is these states that were also the warmest, with temperatures ranging from 4 to 12 Deg F above normal. Missouri sustained several days of heat warnings, with one death in Kansas City caused by heat-related illness. Iowa and Missouri reached more than 100F maximum temperatures on 5 of the 7 days prior to the 5th (Figure 3).
A strong cold frontal passage through the region on September 12, during which Wisconsin, northern Illinois and Indiana, and southern Michigan were especially hard-hit by heavy rain and storms (Figure 4). Minnesota and southwestern Iowa were dry at mid-month, with less than 50% of normal precipitation throughout and some smaller areas receiving virtually no rain. A strong high pressure center moved into the region from central Canada after the second frontal passage, resulting in the first frosts of the season in northern Minnesota, northern Wisconsin, and the Upper Peninsula of Michigan.
On the 20th and 21st, another strong cold front swept through the area from northwest to southeast, causing heavy rain and severe storms on the evening of the 20th. One person died in Zenia, OH, from the effects of an F-4 tornado, and large amounts of crop damage resulted in the Corn Belt. A second cold front and a low pressure center moved through the same trajectory, dumping 1 to 3 inches of rain on southern Iowa, northern Illinois, southern Wisconsin, and southern Michigan, with moderate rains in surrounding areas. Another low pressure center that caused a winter storm in Colorado and Wyoming roared throughout the Midwest from northwest Missouri all the way through to eastern Ohio, dumping 1 to 2 inches of rain in places along its path during the 25th and early on the 26th (Figure 5). Conditions became seasonably cold with this last storm passage, resulting in numerous locations with morning lows in the lower 30s and upper 20s on September 26th to 28th in Minnesota, Iowa, Wisconsin and Michigan. The month ended with several mild and dry days.
The combination of hot and dry conditions brought an end to the positive grain filling stages of the growing season early in the month to the southern part of the Midwest. Even though this is earlier than normal, the growing season started early, so much of the corn crop reached maturity at this time anyway. The excessive heat at the start of the month made for reduced corn and soybean quality ratings at that time. The latest corn production figures released by the USDA on September 12th still call for a record production level, but many experts continue to question the high yield estimates. The USDA corn yield average for the U.S. is at 141.8 bu/acre, down only 0.1 bu/acre from the August estimate. The USDA yield estimate for soybean is 39.5 bu/acre, down only 1.2 bu/acre from the high August estimate.
Corn crops topped 70% good/excellent quality ratings at the end of
September, with soybeans somewhat behind in the 60-70% rating range.
Since the northern areas of the Midwest are behind in their seasonal
development, there must be some concern for frost having ended the
season prematurely, especially in norther Minnesota, Wisconsin, and
Michigan. Although the eastern Midwest is now quite moist, the western
Midwest soils remains very dry, even in areas of Missouri receiving
1-2 inches of rain (Figure 6). Resurgent
drought in Missouri, western Iowa, and central Minnesota is bringing
an end to the growing season by speeding up crop maturation and providing
excellent conditions for the harvest. A substantial number of locations
experienced crop damage from wind and hail, especially in Wisconsin
and Illinois. The corn this season has proven especially susceptible
to lodging, as dry conditions early in the growing season are now promoting
the development of stalk rot that causes the corn to be blown down
easily. Farmers in the local area close to the MRCC are reporting many
cases of disappointing yields relative to expectations.
On September 10th, the first of 2 cold fronts passed through the region. During the first frontal passage, a plume of moist air entered the region from the south (around a large high pressure center) and brought copious rains to southeast Illinois, much of Indiana, and parts of Ohio and Michigan. Flash flood warnings were issued for Mattoon, IL, where more than 4 inches of rain fell on already saturated ground the evening of the September 10-11. The second front entered the region from the north that same evening, bringing large amounts of rain to eastern Minnesota, Wisconsin, Upper Michigan, and northeast Iowa (Figure 4). Eau Claire, WI, received 7.40 inches of rain on the same evening of September 10-11, causing intense flash flooding. During the day on the 11th, most of the rain stayed north of I-80, training from west to east over southern Wisconsin, northern Illinois, and into southern Lower Michigan. In these areas, rainfall totals of 3-6 inches were common during the day. Finally, an intense upper level disturbance kicked the second cold front rapidly to the east, forming a strong squall line extending all the way from eastern Kansas to southern Wisconsin. Meanwhile, strong storms continued training through Chicago, across Lake Michigan, and into Michigan, Indiana, and Ohio. This line of storms collapsed southward, while the cold front moved eastward. Approximately 113 severe hail and 133 severe wind or wind damage reports were received by the Storm Prediction Center (Figure 7, SPC), with the most severe reports coming from northern Missouri, western Illinois, and far eastern Iowa. The strength of the storms died down as the squall line passed through central Illinois, but rain totals of one inch or more were common from central Illinois and points eastward.
The storms on September 10-12 caused quite a few impacts beyond agriculture. In Wisconsin, a person died when they drove into a 15 foot deep sinkhole in an Eau Claire, WI, street and drowned. Power was disrupted throughout the region, with Chicago and Detroit especially hard-hit. In Chicago, 53,000 customers of Com Ed were without power overnight, and the main terminal radar at O'Hare Airport was knocked out. The airport was closed at times and delays were long, with 368 flights canceled. In Detroit, more than 34,000 homes lost power, airport delays were lengthy, and street flooding as deep as 3 feet was prevalent. Many people leaving the Detroit Lions game at the Pontiac Silverdome encountered similar flooding. Detroit and Milwaukee reported the release of millions of gallons of partially treated sewage forced to bypass the treatment plant. Overall, this was the most widespread severe weather event in the Midwest this year.
A very noteworthy severe event occurred on September 20, 2000. At 7:20 PM, the town of Xenia, OH, was struck by an unexpected F-4 tornado that was not detected by weather radar(Figure 8, UIUC Dept. of Atmospheric Science). A severe thunderstorm warning had been issued. Spotters who saw the tornado on the ground provided a few minutes of warning, but only 1 of Xenia's 5 sirens went off during the storm due to the lack of battery power backups when the power failed. One person was killed by a tree falling on his car, 115 were injured (14 requiring hospitalization), and about 250 homes and businesses were seriously damaged or destroyed. Among these were several large buildings, including a grocery store and six churches, two of which were occupied at the time. Preliminary damage estimates by the Ohio Emergency Management agency have reached $40.3 million. Governor Bob Taft declared a state of emergency, and requested a federal disaster declaration for the counties involved in central Ohio. President Clinton declared Greene County to be a federal disaster area on September 26. Weather-related damage was widespread in the western and central Ohio region, not only due to tornadoes, but also due to high winds and hail.
The 2000 tornado struck a section of Xenia that was built since the great F-5 tornado struck the town during the famous Palm Sunday super-outbreak that occurred on April 3, 1974. The paths of the two tornadoes were parallel, but the 2000 tornado produced a narrower damage path just north of the 1974 path that cut a swath several hundred yards wide through the heart of Xenia (Figure 9), Dayton Daily News graphic by John Hancock and Greg DeGroat). The 1974 tornado killed 33, injured more than 1000, and caused over $100 million in damage.