July 10-17, 2006
Midwest Weekly Highlights - July 10-17, 2006
The second week of July featured widespread heavy rains across much of the Midwest, and above average temperatures. The average daily temperature departures across the Midwest illustrate that much of the region was above average for this time of year (Figure 1), with an unusual north-south gradient for the second consecutive week. The northernmost portion of the Midwest, including locations from northern Minnesota eastward into northern Wisconsin and Michigan were actually 5-9°F above average for the second week of July as daily maximum temperatures towards the end of the week topped 100°F. Meanwhile, locations further south, including all of Iowa, Illinois, Missouri, Indiana, Ohio, and Kentucky were above average, but to a lesser extent than the northern locations, generally ranging from 1 to 4°F above average, especially across northern Ohio and lower Michigan. The above average temperatures across the upper Midwest were due to severe drought conditions and a lack of significant precipitation.
Precipitation for the
week was generally widespread and heavy across the lower Midwest,
generally south of about I-80. The heaviest precipitation this
week fell across southern Missouri, northern Indiana, and northern
Ohio. In these areas, locations received between 300 and 500% of
normal precipitation, causing numerous flash floods, while much of
central Minnesota into
central Wisconsin saw less than 10% of normal precipitation (Figure 2).
Much of Illinois, Michigan, Iowa, and Missouri saw
precipitation
totals that between 100 and 175% of normal for the second week of July.
The lack of widespread, significant precipitation
across northern Minnesota and especially north central Wisconsin has
begun to affect streamflows across this region, and drought is
expanding in this area of the Midwest (Figure 3).
In fact, streamflow analysis from the United States Geological
Survey (USGS) shows that many of the major rivers across northern
Wisconsin are running between 2 and 5% of normal discharge for this
time of year, and some of them are even at all-time low discharge rates
(Figure 4).
The lack of precipitation this week has exacerbated the already
stressed environment across this area, and fire danger remains very
high.
Rain, Rain, and More Rain
The cold front that moved through Wisconsin on July 9, producing nearly 3.75" of rain in West Allis, WI, progressed eastward on July 10. Severe thunderstorms erupted across northern Ohio, just south of Cleveland, OH during the late morning hours (Figure 5). These thunderstorms produced numerous reports of wind damage and large hail as they progressed east-southeast towards Pennsylvania late in the afternoon (July 10 storm reports). Heavy rain also fell from these storms, and as much as 6.52" fell in Holmes County, Ohio. Further west, a frontal boundary was stalled across southern Missouri, and warm, moist air riding over this boundary produced widespread heavy rains along the I-44 corridor (Figure 6). Meanwhile, a developing area of low pressure scooted eastward on July 10-12, forcing the warm front north and resulted in numerous showers and thunderstorms across Iowa, Missouri, Illinois, and Indiana (Figure 7). The heavy rain on July 10 across Missouri resulted in a number of flash flood warnings, and the West Plains, MO airport recorded their highest 24-hour rainfall for the date at 4.63", breaking the old record of 1.56" set in 1951. The highest rainfall was found in Laclede County, MO, where a cooperative observer measured 7.25" of rain from the storm system. The saturated ground made it easy for strong winds from thunderstorms to topple trees. In southern Missouri, chainsaws were requested to cut up numerous trees which had fallen on account of the strong thunderstorms.On July 11, Kansas City was inundated by numerous heavy thunderstorms, prompting flash flood warnings, and forcing several road closures. The heavy rain also battered parts of lower Michigan, northern Indiana, and extreme northern Ohio during the evening on July 11. A narrow band of thunderstorms stretched across northern Indiana, which resulted in some very high rainfall totals over a relatively small area. The hardest hit location was a cooperative weather station 1.5 E Oliver Lake, who recorded a staggering 9.00 inches of rain. Other locations include 2NE Millersburg with 8.17", 3W Goshen with 6.65", and Salem Center with 5.60" to name a select few. In Ohio, two tornadoes touched down resulting in F0 to F1 damage to trees and a number of roofs (business and residential) in the towns of Centerville, OH and Carlisle, OH.
On July 12, more heavy rain fell across parts of Illinois, Indiana, and Ohio, as a stalled frontal boundary interacted with a very moist airmass (characterized by dewpoint temperatures in the middle 70's) to produce heavy, slow moving, thunderstorms (Figure 8). Little in the way of widespread severe weather occurred with these thunderstorms, as their main threat was localized flash flooding.
On July 13, an upper level disturbance interacted with temperatures in the middle to upper 90's across parts of western Missouri and western Iowa, northward into western Minnesota, to produce numerous severe thunderstorms with large hail and damaging winds. Radar images from late in the afternoon (Figure 9) show two well-developed areas of thunderstorms, bowing out and moving east-southeast towards central and southern Iowa, and northern Missouri. The storms produced over 125 reports of damage, ranging from trees down, power lines snapped, and measured wind gusts in excess of 70mph (July 13 storm reports).
On July 17, a cold front slowly advanced southward into the Great Lakes region, igniting several clusters of severe thunderstorms across Wisconsin, Michigan, Iowa, and Illinois. Numerous reports of large hail greater than 2.00" in diameter were reported across Iowa, and a swath of damaging winds was found across Wisconsin into Michigan (July 17 storm reports). This cold front, though weak in nature, interacted with temperatures in the upper 90's and dewpoints in the upper 70's (and even lower 80's across southern Wisconsin). Marginally cooler and drier air filtered in behind this front for the evening of July 17.
From the Frying Pan into the Broiler
Once the heavy rain threat passed, an upper level ridge of high pressure moved over the Midwest (Figure 10), and the heat became the final major story of the week. Temperatures in the middle 90's were common across Iowa and Missouri on July 13, and this heat slowly expanded eastward through the remainder of the second week of July. An Excessive Heat Warning was in effect for the Minneapolis, MN area from July 15-16, and for Chicago, IL from July 15-17, and for St. Louis, MO from July 14 all the way through July 19. A host of Heat Advisories and Heat Warnings dotted the Midwest through the end of the second week, including cities such as Kansas City, MO, Webster, IN, and Moline, IL to name a few. High temperatures on July 15 soared into the upper 90's and low 100's across Minnesota and northern Wisconsin, even reaching the shoreline of Lake Superior (Figure 11). Further south, temperatures in the middle 90's combined with dewpoint temperatures in the middle 70's to produce heat index values in excess of 100 degrees for three straight days. Nighttime temperatures offered little in the way of relief from the heat, as lows dipped into the middle 70's, and even close to 80 degrees near Minneapolis (Figure 12).The prolonged period of hot to extreme heat resulted in a few unfortunate deaths this week. In South Bend, IN, a child was playing outside when he went into his parents' unlocked vehicle to play. Sadly, due to child safety locks and no parental supervision, the child was unable to escape from the heated vehicle and died. In Kansas City, MO, and elderly man was found dead after city officials found no working central air conditioning and closed windows & doors in the man's apartment. Several people were treated for heat-related illnesses in Toldeo, OH, and summer school classes held at Middletown City Schools (between Dayton, OH and Cincinnati, OH) were canceled due to a lack of air conditioning.
Despite the hot temperatures, only a few new record high maximum and record high minimum temperatures were set between July 14-17, and interestingly enough, on July 17, each state in the lower 48 United States had at least one observation with a maximum temperature greater than 90°F! The records for this week are summarized in Table 1.
The third week of July is forecast to start warmer and end cooler than normal. Will this come to pass, and how will it affect residents across the Midwest? Find out in next week's edition of the Midwest Climate Watch.
Kruk