Midwest Weekly Highlights - May 18-24, 2009
Little or No Rain
Very little rain fell during the week with most of the region receiving less than 0.2" (Figure 1). Many locations, including large parts of Indiana and Ohio received no measurable rain. The wettest areas, between a quarter and a half inch, were northern Iowa, southern Missouri, extreme southwest Kentucky, and the southwest and northeast tips of Minnesota. Weekly rainfall across the region ranged from 0% of normal to close to 75% of normal near Lake Superior (Figure 2).
Temperatures for the week ranged from 7°F below normal in northwest Minnesota to 5°F above normal in western Iowa (Figure 3). The warmer than normal temperatures extended across the central part of the region with cooler temperatures in northern and southern extents.
The beginning of week three continued the cold pattern from the end of week two with record lows set in seven states on May 18. Then May 19-21 saw a rash of record high temperatures across the northern states (Figure 4). Two locations (97°F in Gaylord, Minnesota on May 20 and 94°F in Big Bay, Michigan on May 21) tied the warmest day on record for any date during the month. Minneapolis reached 97°F on May 19, the earliest on record so warm. Also Milan, Minnesota broke the century mark, reaching 100°F on May 19.
While west central Minnesota was in the triple digits on the afternoon of May 19, 350 miles to the northeast in Grand Marais, Minnesota the 4pm temperature was a chilly 34°F. The difference was caused by strong, warm southerly winds south of a front that divided the state and cool easterly winds coming off Lake Superior on the north side of the front. Around Duluth on May 20, there was a dramatic temperature warming as the front pushed north. The Sky Harbor Airport in Duluth warmed by 41°F (46°F to 87°F) in just 20 minutes around 5pm.
The southerly winds that brought the warmth to the northern states on May 19-21 were responsible for wind damage from Minnesota to Michigan. Although not associated with thunderstorms, the wind and gusts reached up to 50 mph. Minnesota residents reported dust storms that reduced visibility to less than a 1/4 mile. The wind was also blamed for a tipped over 18-wheeler near Cannon Falls, blown down signs, snapped power poles, power outages, and down trees. Damage was reported from southwestern Minnesota to the twin cities. The wind, low humidity, and high temperatures were a factor in a fire near Sanborn, Minnesota and a 10-acre fire outside Minneapolis. Wisconsin and Michigan also reported tree damage and power outages due to poles and lines blown down by the strong winds.
Severe Storms Scarce
There were only three severe storm damage reports for the entire region during the week. This was part of a nationwide pattern of suppressed severe weather. In fact, the Storm Prediction Center had zero reports of severe weather associated with thunderstorms on May 21.
On May 24 a small tornado was spotted along the Mississippi River in southeast Missouri (Pemiscot county). It moved across farmland and caused no damage. Damaging thunderstorm winds occurred on May 23 (McDonald county) and May 24 (Barry county) in southwestern Missouri.
The dry weather was a welcome change for the eastern corn belt. Farmers were able to get into the fields and get some corn planted. Illinois and Indiana, the states furthest behind their 5-year averages, saw big increases in the percentage planted with Illinois going from 20% to 62% and Indiana going from 24% to 55%.
In parts of Minnesota and Wisconsin where drought remained (Figure 5), the dry weather was not as welcome. The continued dryness, along with the record heat experienced midweek, could lead to an expansion of the drought back into upper Michigan and further west into Minnesota.
Flooding concerns on smaller streams and rivers eased with the dry weather. The lower Illinois River remained at major flood stage and other rivers around southern Illinois were at moderate flood stage. The Red River, which had the longest period of flooding at Fargo, dropped below flood stage at all monitoring stations in western Minnesota.