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 27 April 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 with last week’s SMI map.
As of last Saturday, much of the Corn Belt showed conditions somewhat close to seasonal conditions, with a bit drier soils across eastern Iowa and northern Illinois and very wet conditions prevailing across the I-90 corridor. However, next week’s map will likely look much different across northern Missouri and into Illinois/Iowa as significant to excessive precipitation has fallen since early this week in those areas. Recent significant precipitation has left much of the Southern Plains and south-central U.S. moist as well. Next week’s map likely will show even more green in this area as well.
Most of the southeastern U.S. saw little change over the previous week’s map. The latest U.S. Drought Monitor still shows abnormal dryness and moderate drought occurring along the Gulf Coast and into South Carolina, in good agreement with this map. Rainfall has been sparse in this region this week so next week’s map may show some deterioration.
Further north, the SMI is still indicative of somewhat drier than average conditions in the Appalachian region with near neutral SMI’s throughout much of the Mid-Atlantic and Northeastern U.S.