July 18-24, 2005
Midwest Weekly Highlights - July 18-24, 2005
Drought Continues, Heat Wave Develops
During the week of July 18-24, precipitation events chipped away at the edges of the drought region, bringing 1.5 to 3 inches of rain to southeast Minnesota, northern Iowa, southwestern Wisconsin, northern Indiana, southern Michigan, and even some parts of central Illinois (Figure 1). Unfortunately, while some beneficial rains fell in the northern Illinois drought region, they were not sufficient to change the extreme drought status in that region. Worst still were dry areas of northern and central Missouri; only 25% of normal precipitation fell there this week (Figure 2). On top of the lack of precipitation, the drought regions and most of the remainder of the Midwest were severely impacted by a heat wave at the end of the period. Mean daily temperatures were 4-7°F above normal in Iowa and Missouri, while the rest of the Midwest was 2-4°F above normal (Figure 3). This may not seem like a large departure, but the first half of the week was cooler than normal, and the last two days of the period constituted the worst heat wave in the last 6 years in the region. The rains during the week led to some improvements in the U.S. Drought Monitor map (Figure 4, National Drought Mitigation Center) for southeast Missouri, southern Illinois, southern Indiana, and Kentucky, largely reflecting the Dennis precipitation from the last period. However, drought status increased in most of Wisconsin, parts of the northern Illinois, and central and northern Missouri. The heat wave compounds the impacts of the drought on row crops, especially corn that was still undergoing fertilization.
Multiple Precipitation Events Bring Hope....
As the last period finished, a cold front was pushing the remnants of Hurricane Dennis out of the region, so some of the rain in this week's total actually fell before midnight on the 18th. Later at midday, the front was still crossing the eastern Midwest (Figure 5, University Corporation for Atmospheric Research - UCAR), with scattered heavy rain on the edge of the extreme drought region in central Illinois (Figure 6, National Weather Service - NWS). Over the next few days, as a weak boundary between warm and humid and cooler and drier air moved back and forth through the central Midwest, three separate rain events had at least some impacts on the drought region.
The first event on the 19th and 20th consisted of a long squall line of storm sweeping across the central Midwest (Figure 7 - UCAR). However, the upper air support died out, and most of the rain fell in Iowa and Wisconsin and missed the core extreme drought region (Figure 8, NWS). Later on the 20th, an unexpected set of storms developed along the stationary boundary, some of which did bring heavy rain to the eastern edge of the Illinois drought region and other drought areas to the east (Figure 9, UCAR). A storm north of Chicago was strong enough to cut off power to 24,000 customers in Lake County. About 2-4 inches fell in places south of Chicago (Figure 10a, NWS), where 5,000 lost power in central east Illinois. A wide precipitation swath of an inch or more also fell across southern Michigan (Figure 10b, NWS).
The boundary area was active again on the 21st (Figure 11a, NWS) and the 23rd (Figure 11b, NWS). Copious rains fell in arcing trajectories, as both systems moved to the east and then more southerly. The mesoscale convective system on the 23rd was also quite violent, with many severe wind reports in its path (Figure 12, Storm Prediction Center). Winds over 70 mph were measured in southeastern Minnesota and southern Wisconsin, and trees and power lines were downed along a swath several hundred miles long. About 61,000 customers lost electric power in the Minneapolis area, 25,000 lost power near Eau Claire, WI, and 21, 000 lost power elsewhere across southern Wisconsin.
In addition, other convective systems on the 23rd and 24th in the same areas brought more heavy rain to southern Wisconsin, north-central Illinois, eastern Illinois, and large areas of Lower Michigan, resulting in the totals for the week seen in Figure 1. In metro Detroit, more than 40,000 customers lost power during the storms on the 24th, with 9,000 still out the next day. Flint, MI, had a daily record 1.22 inches of rain. While this was beneficial rain to many moderate and severe drought areas, the majority of the extreme drought area in Illinois was missed.
The Midwest drought intensified significantly in central Missouri during the week. Boone City, MO, had gone 46 days without significant rain by the end of the period. Columbia, MO, provided a record 23.7 million gallons to water customers in the face of intense drought and heat. The Quad Cities were using 28 million gallons a day, when normal use was 17 million gallons, so residents were asked to voluntarily conserve water. Crop reports indicated a dire situation for farmers, with corn rated very poor or poor at 56% in Illinois and 37% in Missouri. In Kane, LaSalle, and Will Counties in northern Illinois, 60-80% losses of corn yield are irreversible even if rains do arrive. While rain can help corn kernels plump, most of that crop is already set. Soybeans, on the other hand, could still greatly benefit from further rains.
Heat Wave Takes Hope Away....
On top of the rain missing, the northern Illinois drought core also suffered its worst 3 day heat wave in 6 years. Points further south were very hot for 4 to 5 days. High temperatures from 100 to 104°F were common at the peak of the event on the 24th (Figure 13, courtesy of Unisys Corporation), and heat index values above 105 triggered excessive heat warnings by National Weather Service Offices throughout the southern and central Midwest (Figure 14, courtesy of Unisys Corporation). Quincy, IL, tied its all-time record for heat index on the 23rd, at 121.
In Chicago, the heat emergency plan was activated on the 23rd, and on the 24th more than 40,000 elderly and infirm people on a watch list were called and told about the impending heat wave situation. A number of people that did not pick-up the automated call were then visited by city workers to make sure they were o.k. The 311 call system received 198 calls by persons needing assistance, such as transportation to a cooling center, and these and the other people identified by the phone calls were assisted directly. While three people were reported as suffering heat related deaths in Chicago by the end of the period, two of these were later found to have died of unrelated natural causes. The electrical system was able to transmit 20,800 MW of power on the 24th, a record Sunday for Chicago, without incident. About 70 out of a crowd of 33,000 were treated for heat stress at the Lollapalooza music festival in Chicago on the 23rd and 24th, with only 3 requiring hospitalization. Despite a 104°F peak temperature near Midway airport, and heat index values in the 105-109 range, Chicago fared quite well during the heat wave.
The heat was deadly in other places in the Midwest, with 1 death in Kentucky, 1 death in Ohio, and 1 death in Missouri also blamed on the heat. A number of cities opened cooling centers, including St. Louis, Des Moines, Indianapolis, and Cincinnati. The highest temperature during the heat wave,106°F, was recorded in Osage Beach, MO. Places that reached the 100s were usually a bit drier and sunnier, but heat index values were often as high or higher in the moister areas away from the drought core, where temperatures in the low to mid 90s and dew points in the low 80s meant heat indices above 110. In St. Louis, MO, the heat index exceeded 105 for 5 days in a row. In Milwaukee and Racine, WI, 56 and 50 participants, respectively, in two triathlon were treated for heat stress. In Indianapolis, IN, the American tennis star Taylor Dent was forced to retire from a match due to heat stress. The serious level of heat was well warned by the National Weather Service and widely publicized by the press, and heat wave procedures in many large cities worked well, so losses were minimized. However, in the crop lands of the drought region in the Midwest, the high heat just exacerbated the drought situation.