(weatherwest/swain has a new post up. Good news for west coast US, bad news for that 50-60n band discussed above. AK may stay well above avg for snow cover. Siberia?)
Warm Thanksgiving ridge pattern will likely transition toward progressively wetter pattern around early Dec
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A combination of MJO-related subseasonal forcing and strong El Nino-related seasonal forcing will likely cause the storm track over the North Pacific to increasingly favor California after an episode of strong/dry ridging over the next 7-10 days.
There are, however, growing signs of a larger scale and likely more sustained transition toward a wetter, more active pattern by early to mid December. Long-range traditional weather ensembles are suggesting that this trend will first begin to emerge around 10 days from now, and subseasonal ensembles are currently suggesting a continued escalation of this wetter pattern through December as the broader setup becomes increasingly favorable for the “storm door” to open on a more consistent basis.
In the short term, this possible emergence of a wetter pattern may be partly linked to the eastward progression of an active Madden-Julian Oscillation (MJO) cycle that has the potential to “jump start” the transition. But as we head later into December and into January, I’d expect the seasonal-scale influence of an already quite strong and still strengthening El Niño event to emerge more strongly and to potentially become a major influence on California hydroclimate for most of the rest of the winter.
As I’ve noted many times in the past: when there is a substantial El Niño (EN) event, the atmospheric and oceanic “base state” usually doesn’t reach a point favorable for the Rossby wave perturbations generated by displaced tropical thunderstorm activity (deep convection) to substantially or consistently alter the jet stream over the North Pacific until mid-winter–usually late Dec or Jan. This is why there’s a pretty weak correlation between even strong EN events and autumn precipitation across most of California–it’s just too early in the season. But this year, it looks like subseasonal forcing (from the MJO) will potentially accelerate that process just prior to the time of year when EN-related seasonal influences might be getting their act together.
What does all of this mean, in practical terms? As always, both the MJO and EN offer a tilt in the odds toward certain outcomes rather than a guarantee of any particular conditions in California. But at this time, it does seem that things are lining up for the pattern to become progressively more active and wetter in California starting around early to mid December–and seasonal predictions continue to hint at a relatively high likelihood of wetter than average conditions then persisting through the rest of winter for at least central and southern CA, and perhaps parts of NorCal as well.
Eastern tropical Pacific approaches “Super El Niño ” territory as warming continues
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https://weatherwest.com/archives/33007edit: Was a huge snow event in Siberia 4 days ago, but since the Siberian Times hasn't updated/published anything since Covid19 innoculations there in 2020, there is very little news coming out of the area. Was more fires there in 2021/22 than in all the rest of the world combined. No info if still zombie tundra in 2023, but we have seen lots of the fire observation drones, and some of the fire airplanes used in the mil operation in UA.
