Excessive precipitation in nine months of 2008 produced the second wettest year on record in Illinois. Annual precipitation amounts across the entire state were well above normal, ranging from 43 to 60 inches. Amounts in parts of central Illinois were the highest on record. Precipitation was especially heavy in February, March, and September. All three monthly amounts were the third highest on record. Only August, October, and November had less than average amounts. La Niña conditions existing in the Pacific Ocean during January-July 2008 led to frequent low-pressure centers to develop and a strong jet stream that brought the lows across Illinois, creating numerous storms and heavy precipitation. These unstable atmospheric conditions produced 13 heavy rainstorms during April-July, plus four during January-March, an unusually high number. Atmospheric instability diminished during July and August, but the passage of the remnants of two Gulf hurricanes during September created heavy rains and a very wet September. In December, unstable atmospheric conditions created several low-pressure centers in Colorado, leading to their passages across the Midwest, and causing four winter storms and a wet December in Illinois. Flooding had the most significant impacts in the wet year. Floods caused damages in various parts of Illinois during the January-June period, and 33 counties had major damages to communities, farms, and farmland. Then a very damaging flood occurred in September in northeastern Illinois, causing USD155 million in damages in the Chicago urban and suburban areas. The economic impacts of the wet 2008 are listed below: Property losses from flooding = $645 million Property losses from severe storms = $55 million Losses and costs to railroads = $154 million Government costs (local, state, federal) = USD355 million Total losses and costs from the wet year were USD1.2 billion. These values do not include the losses and costs associated with the extreme cold, numerous winter storms, and high snowfall, which totaled USD3.2 billion. In general, Illinois agriculture benefitted from the odd growing season conditions of 2008. The wet spring weather of the 2008 growing season was poor and delayed planting, but summer and fall conditions were adequate for growth and crop maturity. Corn yields were the second highest on record and soybean yields were higher than predicted, rated as the third highest on record. Water supply wells and reservoirs were recharged during 2008, a major benefit.
|Original language||English (US)|
|State||Published - 2009|
|Name||ISWS Report of Investigation 117|