An active weather pattern will remain across the corn and soybean belt for the rest of May into the first week of June. A large high pressure will strengthen across the Southeast U.S. with hot and dry weather. At the same time, very cool air for this time of the year will be in place in Canada. This will result in an active front going back and forth in the north and central U.S. in the next few weeks. Flood risk persists in the western and northern corn and soybean belt for the rest of May with drying and minor drought areas likely to develop south of the Ohio River, especially in the Southeast U.S.
The overall pattern for the rest of May favors locally heavy rains at times especially over the northern half of Ohio with temperatures bouncing back and forth between normal and above normal.
The last 7-day rainfall map can be found here:https://www.weather.gov/images/ohrfc/dynamic/latest7day.jpeg
For the next two weeks, rainfall is forecast to average 1 to 2.5 inches south of I-70 to 2.5 to 5 inches in the north. Normal is near 2 inches for later May. Expect high variability in rainfall with isolated areas seeing 5+ inches in the far north.
The latest two-week average rainfall forecast can be found here:https://www.weather.gov/images/ohrfc/dynamic/NAEFS16.apcp.mean.total.png
Temperatures and evaporation rates will resume above normal for the rest of May starting in the middle of this week. Temperatures for Memorial Day weekend will see highs in the 80s and lows in the 60s. Normal highs are in the 70s. For the rest of May temperatures will average 4-8 degrees above normal.
Even though Ohio will be on the edge of the heavy rain events the next two weeks, the worst will be the western half of the corn and soybean belt. Rainfall in the western half of the region will average 4-10 inches across parts of Illinois, Iowa, Nebraska, Missouri, Kansas, southern Wisconsin, southern Minnesota and South Dakota.
It still appears that there will be a pattern change for June. The June outlook calls for near normal temperatures and normal to possibly below normal rainfall. The southern areas of the state have a greater chance of below normal rainfall. As we have discussed for a few months now, it appears any drying or cooling in June will give way to normal to above normal rainfall and temperatures again for the second half of summer into autumn harvest season.
The heavy rain event last week created another sediment load on the Mamee River into Lake Erie. Anytime we see over 10,000 cubic feet per second events, that creates load into Lake Erie. There are indications there will be another 10,000 cfs event between May 26-31. Normal flows into Lake Erie drop off to near 2500 cubic feet per second by June.