IEM Daily Feature
Tuesday, 11 May 2021

Increasing GDD Deficits

Posted: 11 May 2021 05:37 AM

As is likely the case most years but as recency bias dictates, the weather this spring season has been a bit crazy. After a rather dry April for much of the state, we are now stuck in a cool pattern which not much in the way of heat unit accumulation and even some freezing temperatures present in the state this morning. From a Growing Degree Day accumulation perspective, we are currently increasing deficits which equates into slower plant growth. The featured chart presents accumulated GDDs for Ames with this year, last year, and the climatology envelope plotted for the period since 15 April. We are currently accumulating about half the daily GDDs than long term average would suggest, so deficits will continue to grow until warmer weather arrives. Longer term models are hinting at warmer weather by the end of May and the forecast for this summer continues to be on the warm side of average, so hopefully these deficits can be made up.

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