November 7, 2022 (next update in the daily weather briefings starting Nov 15)
La Nina will continue for a rare third year (triple dip). La Nina will peak at either a borderline weak/moderate or moderate event. Historically, CenCal and SoCal experience slightly below to below average precipitation during these strengths of La Nina. In general, weak to moderate strength La Nina events do not have a mentionable impact on temperatures.
A weak to moderate strength La Nina will be one of the main general influencers of the West Coast weather pattern through at least mid-winter, thus probabilities favor below average precipitation for central and southern California. Other factors and weather oscillations will come into play now through spring 2023. We’re already seeing an Autumn filled with (so far) several “cut-off” lows affecting California.
Through Tuesday, decent precipitation (1/3-1”+) will occur across most of California. A cut-off low pressure system may additionally bring light precipitation to most of California Saturday night or Sunday through Tuesday (Nov 15). Expect another 1/4-3/4” of rainfall if this comes to fruition.
Thereafter, odds favor high pressure building in across parts of the North Pacific and Western U.S. There’s uncertainty as to how long the anomalous and strong high pressure will stay in place (some of this high pressure is typical during a La Nina, some is not). Although I’m a little concerned about the vastness of high pressure, I see no reason that the current magnitude will continue through Spring and therefore cause another year of significant precipitation deficits. In other words, the pattern is a little weird, but I think it will change as we trek down the road.
I want to stress that it’s far from certain that we’ll end up with much below average precipitation when all is said and done. As we move forward, and as it looks as of this writing, I think we’ll see other weather phenomena kick into “active” phases which could affect the pattern and therefore cause decent rainfall to occur, at times, across California. I also don’t think we’ll be nearly as dry as last year. Preliminarily speaking, I’m expecting 70-100% of average precipitation for the Central Valley and SoCal. Sacramento northward looks to be 75-110% of average. And the snow pack is expected to be somewhere between 70-100% of average on April 1, 2023.
There continues to be at least some support for generally warmer than average mean temperatures through December, with a few periods of below average. However, data has recently signaled that more temperature variability may occur November through January. Signals are slightly increasing that favor an overall pattern of below average mean temperatures for the latter portion of January and February. Although this is suggestive of higher probabilities for periods of colder air intruding into the valley January through early March, the exact pattern setup at the time will be the ultimate determining factor as to the extent of any cold air intrusion into CenCal and SoCal.
*Note that this outlook is preliminary. It is a generalized prediction based on the currently observed and anticipated weather patterns, model data, long term predictions, and historical La Nina trends. This outlook should not be used as a specific forecast, but rather as a tool of future probabilities based on current data signals and expert opinion.
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