TUCSON - The National Oceanic and Atmospheric Administration (NOAA) upgraded their previous La Niña Watch to a La Niña Advisory on Thursday.
According to a discussion released by the Climate Prediction Center yesterday, "La Niña conditions are present and are likely to continue through the Northern Hemisphere winter". The CPC scientists say there is a 75% chance that these conditions will be in place from December 2020 through February of 2021.
So what is La Niña and what does this mean for southeastern Arizona?
What is La Niña?
La Niña occurs when cooler-than-average sea surface temperatures develop across the central and eastern Pacific Ocean, near the equator. This is the opposite of El Niño, which features above-average sea surface temperatures in this region.
What Does It Mean For southeastern Arizona?
A weak La Niña can have varying results for southeastern Arizona. In fact, when equatorial waters remain 0.5 degrees or less than average, temperatures and precipitation can range near normal.
The concern is when these water temperatures become colder than 0.5 from average. These values correlate to a moderate-to-strong La Niña which highly correlate to above average temperatures with below average precipitation.
This would be an unfortunate scenario as much of our region is under a severe drought.
Despite the CPC's forecast of a 75% chance of La Niña sticking around all winter long, the forecast also calls for a borderline moderate event, so if conditions remain below this critical threshold, we may still make out okay.
History says Tucson's average Winter rainfall during a weak La Niña is 2.59". which is just 0.03" shy of average.