WEATHER UPDATE
By Matt Makens Atmospheric Scientist
SUMMER CONDITIONS HINGE ON LATE SPRING MOISTURE AND LA NIÑA ’ S ARRIVAL
Summer conditions will be impacted by several factors related to a transition away from El Niño . Among them : late spring soil moisture , the monsoon outlook , and a swing to La Niña conditions . I hope to break some elements down and then give you a look at how the summer weather pattern may play out .
“ Do spring soil moistures impact summer temperatures ?”
I was asked this great question recently . Let us investigate this briefly .
The idea of wet soil and a cool summer makes sense . An analogy is to stand by a flood-irrigated alfalfa field or a center pivot after a cycle . You will notice how much cooler the area is near that field , depending on how quickly it dries — right ? Now , apply that to a massive scale , and it is a good thought that wetter soil leads to cooler temperatures versus dry soil , which increases heat and heat waves .
There is a correlation between the soil moisture at the end of May and temperatures during summer . For example , research shows soil conditions on May 31 correlate to July ’ s temperatures . The highest correlations come from near the Great Basin , Northern / Central Plains , and areas from the Tennessee to Ohio Valleys . ( I can provide the research papers if you want to see results for your areas ). Granted , this depends on the depths / layers used for the soil moisture values , and land cover / usage can be a source of error using this type of forecast tool . Yet , there is a sizable portion of the country that has little to no correlation between their spring soil moisture and summer temperatures . There are , of course , some issues with this . The amount of soil moisture , the depth of that moisture , land use , and how much additional precipitation falls beyond spring make this forecasting tool interesting but not necessarily a “ lock-it-in ” result ; it has shortcomings .
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