Evaporative Drought Demand Index Foreshadowing Summer 2022 Drought Areas

Latest U.S. Evaporative Drought Demand Index discussion: The current U.S. Evaporative Drought Demand Index (EDDI) clearly identifies much of the southern half of the U.S. as rainfall starved with attendant worsening dry to drought soil moisture. The driest EDDI is located over the Desert Southwest, south-central Nebraska, and parts of eastern Kentucky, the eastern Carolinas and Florida (Fig. 1). The northern U.S. has benefited from cool temperatures, snowmelt and wet periods to cause a EDDI wet surplus. As a predictor of drought for summer 2022, the EDDI implicates The Southwest U.S., central and southern Great Plains to Texas and the Southeast States to immediate East Coast while northern states are less likely to develop a drought condition especially in Southwest Canada, the Upper Midwest and Southern Quebec. The 90-day EDDI change analysis reveals drying for much of the Continental Divide States, central and southern Great Plains to Texas, the Interior Southwest U.S. and the Carolinas while a wetter trend is demonstrated across the Northwest and Midwest U.S. (Fig. 2). The last major summer drought in the U.S. was observed in 2012. During early May 2012, the EDDI implicated Wyoming to Iowa to Arkansas to Georgia for summer 2012 worsening drought ahead (Fig. 3). The August 2012 U.S. Drought Monitor certainly identifies the harsh drought foreshadowed by the May 2012 EDDI analysis (Fig. 4). As applied to EDDI, the summer 2022 drought ahead is focused on the Southwest U.S., central and southern Great Plains to Texas and the Southeast U.S. possibly reaching the Mid-Atlantic States. The only way to turnaround this projection is the intrusion of significant tropical/subtropical rainfall over the next several weeks to the drought-implied areas which is possible in the Southeast States only. Drought implications farther north are possible given the warm SSTA of mid-latitudes in the North Pacific and North Atlantic expected for summer 2022. However, the risk is below average right now. The latest 15-day U.S. rainfall forecast by ECM ENS follows EDDI implications. The outlook is dry across the Southwest U.S. to the central and southern Great Plains and Texas, maintains a wet pattern across the Northwest and offers expected rainfall to ease Southeast U.S. drought risk (Fig. 5).

Fig. 1: The current U.S. Evaporative Drought Demand Index.

Fig. 2: The 90-day change in U.S. Evaporative Drought Demand index.

Fig. 3: The EDDI analysis for May 8, 2012.

Fig. 4: The August 2012 U.S. Drought Monitor.

Fig. 5: Latest ECM ENS 15-day percent of normal rainfall forecast.