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Date: 3/22/2021

Title: La Nina Update

Since the spring of 2020 we have been talking about La Nine extensively has it has had an impacted on our weather since then. Whether or not La Nina continues into the rest of spring and summer could play a large role in our weather this spring, summer and fall.

A continuation of La Nina this spring and summer could mean drier than normal conditions in many areas of the west, southwest and some areas of central USA. If La Nina fades away or weakens, that may indicate that conditions will not be as dry this spring/summer.

One trick aspect of tracking La Nina has head into spring, is what we call the “barrier season”. The “barrier season” happens in springtime when the sun if focusing a lot of its energy on the equator. This causes sea surface temperatures to change some and can mask the impacts of La Nina or El Nino. We will have to wait to mid to late summer before we will know for sure if La Nina will continue or possibly fade away.

We have just received the most recent forecast for La Nina/El Nino. Compared to December, La Nina has weakened some as sea surface temperatures have moderated some, however, sea surface temperatures in the eastern and north Pacific have turned colder.

The graphic below shows the forecast for sea surface temperatures across the Pacific near the equator. The solid green line shows the average of all the computer projections. As you can see the green line gets close to the zero line but stays slightly negative (neutral or weak La Nina through summer and early fall). If the modeling ends up being correct, La Nina may be weaker than the summer/fall of 2020. It would be good news for the western states and some parts of the central areas of the USA if La Nina continues to weaken (better precipitation chances). However, we won’t know for sure until we get a new update in April when the summer forecast will become more clear.