Midwest Overview - May 2013

Cool West, Warm East

The Midwest saw a contrast of temperatures during May. Areas around Lake Superior and southward through Iowa and Missouri were a few degrees below normal. Around the other Great Lakes and south to about the Ohio River temperatures averaged slightly above normal for the month (Figure 1). The coolest area was in central Minnesota at about 3°F below normal and the warmest were in parts of Michigan and Ohio at about 4°F above normal. During the month hundreds of daily temperature records were set with a mix of record cold and record warm alternating as storms moved across the region (Figure 2). The warmer temperatures in the eastern Midwest brought the spring (March-May) temperatures up to about normal in Ohio and parts of eastern Indiana and Michigan. The cooler weather to the west reinforced the cool spring pattern with parts of west central Minnesota as much as 8°F below normal for the season (Figure 3).
 

Wet West, Dry East

The east-west split in the weather pattern was seen in precipitation as well in May. Heavy rains across northern Missouri into west central Illinois as well as across most of Iowa and into southeast Minnesota and western Wisconsin dropped 4"+ across broad swaths of the region with totals topping 15" at some stations in Iowa (Figure 4). The biggest totals in Iowa were around Marshalltown (Marshall County) where two stations reported 15.75" and 15.93" for the month, more than three times normal. Many rainfall records in Iowa fell including the May statewide record according to preliminary numbers. Further east, drier conditions were the rule with most of Ohio picking up 2" less than normal for May. Spring totals in the Midwest were below normal along the Ohio River and across Ohio. The rest of the region was above normal for the season. Parts of six states recorded spring rain totals exceeding 150% of normal with parts of Iowa and Minnesota exceeding 300% of normal (Figure 5). During the month several hundred daily precipitation records were set. Spring (five states) and year-to-date (six states) totals ranked among the 10 wettest on record back to 1895 in the western states with Iowa setting a record for the month, season, and year-to-date periods and Illinois and Michigan also setting records for the year-to-date.

May Snow Storms

A late season snow storm dropped significant snow in the first week of the month (Figure 6). Snow fell from southern Missouri northward to the southwest shore of Lake Superior. Totals ranged from a few inches in Missouri to more than a foot in parts of Iowa, Minnesota, and Wisconsin. The largest totals were in the 17" to 18" range in the latter two states.
 

Severe Weather

Cool spring weather had suppressed severe weather in the Midwest this spring but May brought enough warmth to kick off storms across the region (Figure 7). Tornadoes were reported in Iowa for the first time since May, 2012. Tornadoes also touched down in Minnesota, Wisconsin, Michigan, Missouri, Illinois, and Indiana. Hail and wind damage reports were widespread across the region.
 

Spring Planting

Cool, wet weather had delayed planting through most of April in the region. May brought some windows of opportunity to plant and farmers were ready to take advantage. Corn planting rapidly progressed in May bringing it near the 5-year average after being way behind at the beginning of the month. Areas further east were at or slightly ahead of the average while areas to the west were still behind the average by a few days. Soybean planting remained a little further behind in the western half of the region.

-MST-