During the 2019 growing season, Dr. Eric Hunt of Atmospheric and Environmental Research, Inc. will be providing weekly updates of the soil moisture index (SMI) from the Noah-MP land surface model in the NASA LIS framework for the eastern 3/4 of the U.S. where row-crop agriculture is more common. The Evaporative Stress Index (ESI) will also be included in our analysis once data for all of the U.S. are available later this season. The analysis is intended to provide the larger agricultural and meteorological communities insight as to areas where soil moisture is excessive or deficient compared to average for that location and what that may mean for impacts. It is my goal that these maps can be an early warning signal for flash drought development or where flash flooding could be likely in the coming week if heavy precipitation materializes. Please be advised that the SMI should be viewed as complementary, not a substitute, to the U.S. Drought Monitor (USDM) and that declarations of drought for a particular location should never be based on the SMI alone.
This blog post was partially supported by NASA grant NNH16CT05C.
Figure 1. The Soil Moisture Index (SMI) for the 7-day period ending 11 May 2019. Results are based on output from the 0-1 m (surface to 3.23 feet) layers in the Noah-Multiparameterization (Noah-MP) land surface model. Noah-MP is run in the NASA Land Information System (LIS) framework with the North American Land Data Assimilation Version 2 (NLDAS-2) forcing dataset. The SMI calculation is based on the soil moisture index created in Hunt et al. (2009) such that ‘5’(dark green) is the wettest and ‘-5’ (dark red) the driest for the period of record. The period of record used calculate the SMI for the current map is 1979-present.
Figure 2. Comparison of this week’s SMI map the last three week’s SMI maps.
Significant precipitation that has occurred over the past few weeks in the central U.S. has left soils very moist for this time of year. The SMI was indicative of excessive moisture across much of the Great Plains, particularly across Kansas and central Texas. This extended east into Arkansas, Louisiana, and Mississippi. The Western and Central sections of the Corn Belt remained moist, with excessive moisture persisting across the I-90 corridor. This moisture has had a negative effect on planting, with most Corn Belt states being way behind schedule on planting according to the latest Weekly Weather and Crop Bulletin. The forecast next week isn’t likely to help matters much.
The latest U.S. Drought Monitor still shows abnormal dryness and moderate drought occurring along the southeast coast. This was in good agreement with the SMI, though there was improvement in the region from last week to this week.