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Midwest Weekly Highlights - May 15-21, 2015

Wet Week in the West

Wet weather was the main story this week across the western reaches of the region as multiple rounds of showers and thunderstorms moved through (Figure 1).  Most of Missouri and Minnesota saw above normal precipitation while western Iowa also skewed above normal (Figure 2).  Heavy rain in the western half of Missouri also spawned flooding throughout the state on the Missouri River.  The western half of Kentucky had an inch of precipitation or more above normal for the week.  Elsewhere, dry conditions were common along the southern shores of Lake Michigan and the eastern Ohio River valley.  In most cases, these areas had less than half the normal precipitation for the week (Figure 3).

East-West Temperature Split

Above and below normal temperatures across the region were largely split from east to west this week (Figure 4).  Above normal temperatures were in place across the region to start the week (Figure 5), while below normal temperatures took over for most areas to end the week (Figure 6).  Temperatures were 10-18°F below normal across Minnesota and Iowa to end the week, leading to below average temperatures for the whole week.  The coldest areas were in the western parts of these states, with average temperatures 4-8°F below normal.  To the east, temperatures 6-10°F above normal to start the week helped keep temperatures above normal for the whole week.  The most above normal areas were in eastern Kentucky and Ohio, where temperatures were 3-6°F above normal.

Severe Weather May 15-17

All but two storm reports for the week came from three days of storms from May 15-17 (Figure 7).  On May 15, strong thunderstorms formed from Missouri through central Illinois and eastern Indiana.  The gust front from these storms knocked over trees and power lines.  A few storms also fired in Missouri, where recreational vehicles tipped over from strong winds, causing two minor injuries.

The most potent storms came on May 16.  The main low pressure system organized in the eastern Dakotas.  The storm's cold front stretched south though western Iowa & Missouri and continued into Oklahoma & northern Texas.  Along the cold front, strong storms fired, causing wind damage from Iowa through Missouri.  Embedded EF-0 & EF1 tornadoes were surveyed by the National Weather Service in this line of thunderstorms.  Closer to the main low, tornadoes formed in central and western Minnesota.  According the National Weather Service-Chanhassen, 15 separate tornadoes were reported in Minnesota, but storm surveys were still being taken at the time of writing.

While May 17th looked like a conducive day for strong thunderstorms, very few formed across the region.  A few reports of downed trees were widely scattered in the region, but no major incidents occurred However, a weak supercell thunderstorm did spawn Wisconsin’s first tornado of the year on that day.

Drought Relief Comes to Minnesota

After another wet week in Minnesota , the National Drought Mitigation Center has brought over 40% of the state out of drought conditions (Figure 8).  With western Minnesota seeing above 200% normal precipitation so far this month (Figure 9), severe drought conditions have been downgraded to moderate drought as well.  This is great news for farmers across the state that planted crops earlier this year due to good field work days this spring. As of this week, 97% of the state’s corn crop and 79% of the soybean crop has been planted across the state according to the National Agricultural Statistics Service. Elsewhere across the Midwest, no major changes occurred as moderate drought in Wisconsin held status quo yet another week (Figure 10).