La Niña seems to be weakening
The residents of North Idaho and surrounding regions continue to be in the middle of the “third” winter that should continue into early March. From last week’s column, our “first” winter came in early November and then the “second” one came in the middle of December.
Since Valentine’s Day, Feb. 14, Cliff has measured around 30 inches of snow. From that period of Feb. 14 - 19, we had 4 major snow storms in 5 days, producing about 2 feet in of snow in the lower elevations. Of course, that was another record.
Cliff told me that if we had this kind of snow like we’ve seen since Feb. 14 for an entire winter, Coeur d’Alene would likely end up around 213 inches. During the record year of 2007-08 when the all-time record 172.9 inches fell, there was virtually no snow in November of 2007. He told me that if we would have seen a snowy November and a snowy April, the total for that season about 10 years ago would have been over 200 inches.
As of early Sunday, about 82 inches of the white stuff has fallen, compared to the normal of 69.8 inches. It’s very likely that we’ll end up with at least 90 inches for the 2017-18 season. There’s even an outside chance we could end up around 100 inches, especially if we get more snow during the first 10 days of March.
Cliff and I are already getting questions on when temperatures will warm up. After all of this frigid weather, it’s almost hard to believe that we had a record 58 degrees on Feb. 8. Last week, readings dropped into the single digits as Cliff recorded a 3-degree reading on Feb. 20. Sprit Lake went to minus 12 degrees and Athol dropped to minus 8 degrees. From record warmth to record snows and frigid temperatures in a short period of time. Our cycle of wide weather “extremes” continues with no end in sight.
Once we get through this pattern of cold and snow, we’ll likely go to the other side with warmer temperatures. We could see our first 60-degree reading by the middle of March. Though readings will be higher later next month, Cliff and I are still predicting above normal moisture totals through the early portion of April.
One of the big reasons we got the snow was the cooler-than-normal sea-surface temperature phenomenon, La Niña, in the waters of the south-central Pacific Ocean. When ocean waters cooled down last year and continued into early 2018, most scientists called this a “weak to moderate” event. The last big La Niña occurred in late 2007 and 2008, when we had the record snowfalls across Coeur d’Alene and the rest of the Inland Northwest.
It now appears that the cooler-than-normal sea-surface temperature event, La Niña, will be with us through the early portion of the spring season. According to the National Oceanic and Atmospheric Administration, NOAA, this current weak-to-moderate La Niña has likely reached its peak and will weaken over the next few months. There were some isolated regions along the Equator with sea-surface temperatures as much as 3-5 degrees below normal last month. Since then, those areas have moderated quite a bit.
The latest forecasts continue to have La Niña weakening over the next several months. Then, if this trend continues, ocean waters should cool to the in-between warmer El Niño and La Niña event, which we call La Nada, sometime around May or June.
Sea-surface temperature data still shows cooler ocean waters along the Equatorial regions. However, readings have moderated to slightly above normal levels right along the West Coast of South America. This is another indication that the La Niña event will likely fall apart this upcoming spring.
This area also needs to be watched a little more closely. If ocean temperatures warm up dramatically during the summer and fall, we could be talking about the formation of the warmer El Nino event. This phenomenon will often lead to much less snow for our part of the country during the winter seasons. Right now, it’s too soon to tell.
According to Australia’s Bureau of Meteorology, the Southern Oscillation Index, the air pressure differences between Darwin and Tahiti, expanded toward the positive late last year, which indicates the La Niña event. However, the latest readings are going toward the negative side, which means that ocean conditions are changing to the warmer side.
However, if La Niña manages to hold on to life through the spring season, or even if we see the in-between “La Nada” sea-surface temperature event, it’s possible that we could turn warmer and drier later in the spring. Let’s hope that we don’t dry out too much and have another difficult fire season.
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Contact Randy Mann at randy@longrangeweather.com