Ag Weather Forum

Notable Soil Moisture Deficits

Bryce Anderson
By  Bryce Anderson , Ag Meteorologist Emeritus
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Crop areas in the northern Midwest, northern and southwestern Plains, and the northwestern U.S. have well-under 50% of average soil moisture. (NOAA/CPC graphic)

It is now about six weeks since record-breaking precipitation moved through the Central Plains and portions of the Midwest. That robust outpouring of moisture has some limited follow-up, with the result being a definite have and have-not situation when it comes to soil moisture in the primary crop areas of the United States.

As of April 25, 2021, a swath of territory from east-central South Dakota south and east to northern Oklahoma and including much of Missouri have soil moisture anomalies that are in the 70th to 90th percentiles -- an indication of heavier supplies of soil moisture than average by quite a margin. Examples of this heavy precipitation include record-wet March precipitation in Casper, Wyoming; Grand Island, Nebraska; and Goodland, Kansas, according to the NOAA Central Region.

However, there is a sizeable side of the moisture coin inhabited by quite a few areas in the lower 48 states that is very dry. This situation includes: the majority of the Great Lakes acreage; northwestern and north-central Iowa through south-central and southeastern Minnesota; the spring wheat areas of the Northern Plains; irrigated agriculture in the Nebraska Panhandle; the southwestern Plains; all but northeastern Texas; and the entire Pacific Northwest. In the north-central U.S., the NOAA Central Region identified Dickinson, North Dakota as having experienced the driest March on record; Bismarck, North Dakota had the third-driest March on record; and Mobridge, South Dakota had the fourth-driest March on record, to cite a few examples.

That's a lot of ground and a lot of productive ground where the soil bank doesn't have a lot of currency left in the ledger. In addition, we're now at the point in the vegetation cycle when it's not quite impossible, but certainly difficult, to add appreciable moisture to the soil profile. That's because of plant root systems getting more active and drawing moisture out of the ground to maintain plant health, along with the stronger and longer sun presence every day leading to more and more evaporation and drying out of the ground.

Looking to the next seven days, precipitation forecasts place some moderate totals in the Great Lakes with up to 1 inch. There is also a chance for localized areas of the Southern Plains in the vicinity of the Front Range of the Rocky Mountains in Colorado to receive localized heavy precipitation. Elsewhere in the drier areas, no more than a quarter of an inch total precipitation is featured in the forecast. For the areas where precipitation is on the "have-not" scale, this keeps concern very high as we head for the late spring period. This is in addition to prospects for drought emergency declaration in Northern California; drought over 85% of Mexico; and the increasing Canadian Prairies drought as well.

Bryce Anderson can be reached at

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Morris Drummond
4/26/2021 | 3:29 PM CDT
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