POTENTIALLY STORMY CHRISTMAS WEEK ON TAP

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As we’ve been reporting in recent updates, the long dry (and foggy) spell over Northern California is likely to end around mid-December. That’s when the first of what’s shaping up to be a series of progressively stronger storms my impact NorCal and the North Bay.

The satellite view on Thursday shows what we’ve been dealing with for weeks. Radiation (Tule) fog building up in the Central Valley and spilling into the North Bay valleys.

Right now strong high pressure is over the West, and a blocking low pressure system has been stuck over the Eastern U.S. That’s kept our weather stagnant and sent the storm track (black) into the Pacific Northwest, where they’re experiencing flooding.

By the 16th or so, low pressure in the Eastern U.S. is forecast to (finally) weaken and move along, allowing low pressure out West to strengthen and dig further south, flattening the high pressure system over California. This will likely send the storm track pretty much into Oregon and NorCal.

Further out in the long range, after about December 20th, low pressure should be able to dig further south off the California coast, bringing the storm track with it. And, hopefully, wet weather to much of the state.

Most models show the first weak storm arriving around the 15th or 16th of December, then rain or showers continuing off and on until Christmas Day or even further. And, if the models are to be believed, the storms may progressively get stronger.

Of course we’re all skeptical at this point, but among weather forecasters confidence is growing that this pattern change is real due to several days of widespread agreement among the various models.

We’re not going to show any specific storms at this point, as that will likely change. But all of the models agree that a wet period is on tap for the 3rd week of December, and maybe the 4th week as well.

Here’s where the storm track is projected to be in the days before Christmas.

And here are the European ensemble, the European AI ensemble, the GFS ensemble, and the Canadian ensemble models, showing the departure from average precipitation from December 19th-24th. The big four seem to be on the same page.

More updates to come.