Flooding Rainfall Ahead for Great Plains

Dangerous North-turning Major Tropical Cyclones Bring Excessive Rain to Japan & Southwest U.S.
09/28/2018, 5:38 am EDT
3 North Pacific Intense Tropical Cyclones
10/03/2018, 5:44 pm EDT
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A persistent chill enhanced by advancing snow cover over the North-Central U.S. into the middle third of October is separated to the East by unusually warm climate. In-between a zone of heavy rain will persist bringing flooding rainfall across areas where soil moisture has already increased significantly during late summer.

Rapidly Wetter Soil Moisture Trend in Great Plains Accelerates

Discussion: Ranking in the 95-99% wettest on record excessive soil moisture is present in Iowa, parts of Texas and certainly the Mid-Atlantic region on the last day of September 2018 (Fig. 1). While Florence soaked the Mid-Atlantic region in September historic rainfall also occurred in Texas where a near statewide much wetter soil moisture profile was observed (Fig. 2). The wet conditions in the Great Plains accelerate as ECMWF forecasts over 10 in. of rain the next 10 days from Oklahoma to Iowa certain to cause dangerous flooding (Fig. 3).

Fig. 1: NOAA analysis of soil moisture anomalies on the last day of September 2018 identify extreme wet conditions in Iowa and of course the Mid-Atlantic.

Fig. 2: NOAA analysis of soil moisture change in September indicates a dramatic wetter change in Texas, Iowa and the Mid-Atlantic region.  

Fig. 3: The 10-day ECMWF precipitation forecast indicates 10+ in. of rain in parts of the Central/Midwest U.S. likely to cause flash flooding (while the Mid-Atlantic is drier).