Extreme and Persistent Rains and Flooding in the Midwest - Can it happen across the Northeast?

Aerial view of flooding in the Midwest by USDA's Sec. Sonny Perdue

By David Hollinger, Director, USDA Northeast Climate Hub

 

The extremely wet conditions across the Midwest and other parts of the U.S. this spring led to disastrous floods and delayed planting.

The USDA Weekly Weather and Crop Bulletin (June 25th edition) reports that by June 2, only 67% of the nation’s corn and 39% of the soybeans had been planted. These low rates broke records of 77% and 40%, respectively, set back in 1995. The late planting now means that crop development is lagging and prices are rising.

In the Northeast, NOAA’s National Centers for Environmental Information (NCEI) reported that spring (March-May) rainfall was above average except in PA (well above average) and MA (average). Temperatures during this time were below average in Maine, average through New England and NY, and several degrees above average in MD, DE, and WV. At the end of June, soil moisture in the region was adequate or in surplus, with much of NY, VT, and MD reporting surpluses.

Extreme flooding in the U.S. is associated with certain atmospheric circulation patterns.

Researchers recently used machine learning to identify 12 patterns leading to extreme flooding. The recent Midwest flooding resulted from the presence of two patterns. The first, “Central Winter Storm”, brought heavy rain-on-snow in the north central U.S. and heavy rains in the south in March and April. The second pattern is related to consistent moisture transport from the Gulf of Mexico. This added additional rain to parts of the Midwest in May and June.

Persistent flows of moisture coming off the Gulf of Mexico are also a leading cause of heavy rains and flooding in the East. Tropical cyclones (hurricanes) are another important pattern leading to eastern flooding. It is too early to say if climate change is modifying the frequency of circulation patterns associated with extreme flooding. However, chapter 9 the U.S. Climate Science Special Report finds high confidence for increases in projected rainfall rates from Atlantic hurricanes and medium confidence for increases in storm intensity.

One bright mark amidst the gloomy spring is that the wet conditions caused drought conditions in the U.S. to fall to a U.S. Drought Monitor-era record low of 2.3% on April 23rd. According to the Climate Prediction Center, drought is now unlikely across most of the U.S. this summer.