Spring 2020 Weather Outlooks and Potential Crop Impacts

Spring has sprung! Preparations for planting across the state are in full swing. Conditions over the last 30 days have been unseasonably warm across the Midwest with positive departures of anywhere from two to four degrees. Early March had a good stretch of dry conditions; the second half of the month experienced a more active storm track in which rainfall (and some snow) fell every few days. With the recent wetness, the last thirty days were also wetter-than-normal.

Soils remain wet from fall 2019, which was the seventh wettest in 148 years of statewide observational records, following the 12^th wettest year on record. Taken with 2018, the two-calendar year stretch has been the wettest two-year period on record. There is a silver lining, though. Conditions moving into the 2020 planting season are better than they were at this time last year. Additionally, the above average temperatures and some windy days also helped to dry soils out beginning in early March.

Source: NOAA.

Looking at the Climate Prediction Center’s (CPC) short-term outlooks into mid-April, probabilities indicate very high probabilities of unseasonable coldness with a slight chance of wetter-than-normal conditions. Overnight lows are expected to dip down into the 20s this weekend and into early next week.

While these temperatures shouldn’t impact row crops since corn and soybean planting hasn’t started quite yet, specialty horticulture crops may be impacted as well as forage crops. For forage crops like alfalfa, there is the potential to see some frosted leaves in established stands, but plants should be fine. New alfalfa seedings that may be up have very good frost tolerance due to two main factors. One is their proximity to the soil and the soil’s radiant heat relative to the colder air temperatures. The other is that seedlings have a rather high concentration of solutes (sugars and other compounds) in the cells that help lower its freezing point. If new seedings are frost damaged, they will first appear to wilt and then die over the following 3 to 5 days. As long as at least one set of leaves escapes damage, the plant should recover. Wait a week after the frost and estimate living plants per square foot. If more than 20 plants per square foot remain, the stand will survive in good shape. If there are fewer than 15 plants per square foot, consider interseeding more alfalfa into the stand.

The final April outlook from the CPC shows a slight decrease in the probability of wetter-than-normal conditions, which were found in the initial April outlook released in mid-March. The temperature signal also suggests higher chances of warmer-than-normal temperatures for much of Iowa. What we see in the April outlooks is mirrored in the April-May-June outlooks: elevated chances of warmer and wetter conditions.

Farmers should be mindful of soil conditions, given the current wetness across much of Iowa. Compaction issues are still a concern. Soil temperatures have been trending up across the state over the last few days with upper 40s and low 50s in western Iowa to upper 30s and low 40s in northeastern Iowa. Taken as a whole, farmers should be ready to go when short-term outlooks and forecast show windows of favorable weather.