By Jim Noel, NOAA
After a wet spring was forecasted since January, it appeared in April that a window would open in May. The rain total window has however, the frequency window has not. The rainfall the last two weeks in Ohio has averaged 1.5 to 2.5 inches with some streaks above 3 inches and some below 1.5 inches. Normal for this period is 1.5 to 2.0 inches. The reality is the ground is just so wet from the wet period up to May. The other BIG key is the frequency of the wet weather.
Often, when it is wet in say the eastern U.S., it is dry in the western U.S. The opposite also holds true. However, we have a very active and progressive weather pattern all around the northern hemisphere. This means a lot of weak to moderate storms on a continuous basis. It is not just Ohio either. Boston set a record for most days with measurable rain in the month of April.
Much of the U.S. is very wet right now.The latest soil moisture rank shows most of the corn and soybean belt is in the top 1 to 5%. https://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/Figures/daily/curr.w.rank.daily.gif
There are some questions on similarities to past years. Yes, you can see some similarities to 1993 or 1965 or 1948 and 1949 but there is no perfect year. It depends on where you are. From the widespread wetness in the U.S. you have to look at 1948/1949 for a closest fit but even that does not.
Going forward for the rest of May, we will be seeing increasing temperatures which will lead to increasing evapotranspiration. Hence, like most years, even with some rainfall, the ground will begin to dry in the top layers.
Up to May 16, temperatures will be below normal. However, starting May 17-May 31 the second half of May will see above normal temperatures and evapotranspiration so things will dry some. Rainfall for the rest of May will average close to normal in the 1.5-3 inch range as seen in this link…https://www.weather.gov/images/ohrfc/dynamic/NAEFS16.apcp.mean.total.png
Looking ahead to the summer growing season, not much has changed. We expect near to slightly above normal temperatures from June to August. However, due to the wet soils, we expect normal daytime temperatures and above normal nighttime temperatures similar to last summer. Humidity levels will be above normal this summer too with all the evaporation. Therefore, expect increased issues with mold and mildew. As for precipitation, June looks like a variable month with areas of above and below normal precipitation. That could create some early challenges for growing if you get areas of hard ground near the top soil with wet ground beneath. As we get into July and August, indications are for a little wetter than normal pattern to resume.