April 24-30, 2017
Midwest Weekly Highlights - April 24-30, 2017
Excessive Rainfall
A powerful storm system coupled with several more days of moderate precipitation led to record rainfall for many across Missouri, Illinois, Indiana and Ohio (Figure 1). Rainfall amounts of four to six inches were widespread across Missouri, southern Illinois and extreme southern Indiana. Locally heavy amounts of eight to ten inches were also reported. Nearly a dozen cooperative network stations in Missouri reported more than ten inches of rainfall for the period. Most of this precipitation fell during a two-day period through the mornings of April 29 (Figure 2) and April 30 (Figure 3). The highest weekly total in Missouri was in Houston (Texas County) with 12.98 inches, while the highest daily total was 8.50 inches through the morning of April 30 in Tecumseh (Ozark County). Heavy rain in Illinois included a high weekly total of 10.69 inches in Carbondale, IL (Jackson County) with a high daily total of 5.21 inches through the morning of April 29. Observers in the CoCoRaHS network in Indiana observed 8.32 inches near Stendal (Pike County) and 8.11 inches near Huntingburg (Dubois County) through the morning of April 29. Nearly 300 precipitation records were broken during the week (Figure 4). More than 200 of these records occurred through the mornings of April 29 (Figure 5) and April 30 (Figure 6).
This heavy rainfall led to large departures from normal
(Figure 7). Many areas in Missouri and southwestern Illinois had more than five times the normal amount (Figure 8). Most of Indiana, Ohio, eastern Wisconsin and the U.P. of Michigan had more than twice the normal amount as well. Only a few areas were drier than normal in northern Iowa, southern Minnesota, northern Lower Michigan and Kentucky.
East to West Temperature Divide
Temperatures across the Midwest were divided from warm weather to the east and cold weather to the west
(Figure 9). Parts of Iowa and Minnesota were 8-12°F below normal. Meanwhile, eastern Kentucky and Ohio were 6-8°F above normal. A powerful cold front slowly moved through the region during the last few days of the week, which was a major reason for the divide. Maximum temperatures reached the 80s in the eastern half of the region on April 26, while northern Minnesota was below freezing (Figure 10).
As the cold front moved east towards the end of the week, temperatures still remained warm across southern and eastern areas of the region (Figure 11). The divide in temperatures led to both daily highest temperature records (Figure 12) and daily lowest temperature records
(Figure 13).
Major Flooding
Heavy rain in Missouri, southern Illinois and the northern Ohio Valley on April 29-30 caused major flooding along many rivers and streams (Figure 14). Several stream gauges set records in Missouri. A record crest on the Gasconade River at Hazel Green, MO (Figure 15, Laclede County) led to the closure of I-44. Another record crest occurred on the river near Jerome, MO (Figure 16, Phelps County). The Meramec River, which set records from heavy rain in December 2015, was near-record stage at many gauges, with a record crest near Steelville, MO (Figure 17, Crawford County). Two deaths were reported from the flooding after cars were swept off the road, while over 100 rescues and evacuations occurred across Missouri. The Mississippi River was in minor flood stage from the Iowa/Missouri border through Arkansas. Moderate flooding was occurring from St. Louis, MO (Figure 18) through Thebes, IL (Figure 19, Alexander County). Major flooding was forecast to occur in these areas along the river during the first week of May. Other major rivers in the region that were affected by flooding included the Illinois River, the White and Wabash rivers in Indiana, and the Ohio River.
Severe Weather
Widespread severe weather occurred during the week across the southern half of the Midwest (Figure 20). Over 250 wind, hail and tornado reports were reported. Strong winds were common in southwestern Missouri on April 25, including an EF-0 tornado near Golden, MO (Barry County). These storms moved east on April 26, causing 60-70 mph winds along a line from south-central Missouri to eastern Michigan. An EF-1 tornado was also observed near Clinton, KY (Hickman County).
The main severe weather event occurred during the last three days of the week. Stalled thunderstorms from southern Missouri through southern Ohio caused hail damage as well as scattered high winds on April 28 (Figure 21). Two-inch hail was also reported at Grassy, MO (Bollinger County) and McCutchanville, IN (Vanderburgh County). Two tornadoes were reported near Sumner, IL (Lawrence County) and Goshen, KY (Oldham County). The system continued to create severe weather in the southern half of the region on April 29, with a line of storms in southern Illinois causing wind damage from 60-70 mph winds (Figure 22). Two tornadoes were reported and included an EF-0 tornado near Kampville, MO (St. Charles County) and an EF-1 tornado near Miles Station, IL (Jersey County). The system moved further east on April 30, causing wind damage across central Kentucky, with scattered reports across eastern Ohio (Figure 23). Gusts of up to 62 mph were reported, with trees and power poles snapped.
-BJP-