BIG NORTHERN CALIFORNIA RAIN AND SNOW ON TRACK FOR THURSDAY-MONDAY

Share with Friends

The storms that have long been forecast for the first week of December across the North Bay are now firmly in the medium term forecast window, and four days until the first rains arrive, they continue to look impressive.

For more than 24 hours, the once-swerving model runs have been in pretty good agreement on strength, timing and rainfall amounts. That’s good news. By Tuesday, a wave south of Alaska will form into a deeping low. (Image 1)

By Thursday, this gathering storm system is expected to bring a cold front to the North Bay. At this point, it appears the storm may tap into a feed of moisture northeast of Hawaii, enhancing rainfall. (Image 2)

Looking at the precipitable water forecast, both the GFS and European models (Image 3) show this strong moisture connection.

Rain looks to arrive sometime in the morning to early afternoon Thursday, and last into early Friday.

Rainfall may reach 1-2 inches across the North Bay by Friday afternoon. Potentially more in the wettest spots. The WPC blended forecast averages wet and dry models. (Image 4)

On the high end is the European model, showing a real drenching by early Friday. (Image 5) For all the optimists out there, this is fun to look at, but we’ll stick with the WPC averaged forecast for now.

Hot on the heels of this system will be a 2nd storm, which forecast maps show winding up off the Pacific Northwest coast on Friday, even as our first storm departs. (Image 6)

This second storm should arrive Saturday morning or afternoon, and finally clear out late on Sunday. (Image 7)

Rainfall totals by Monday could be impressive. This is the WPC blended model. (Image 8) The European model is even wetter, and GFS model is drier.

The storms will bring in cold air, keeping California temperatures well below normal for the next week to 10 days. (Image 9)

And, after clearing skies and cool weather, there are suggestions in the long range forecasts that low pressure, and possible rain, may return around the 10th or 11th of December. (Image 10) But that’s too far in the future to have any confidence in. We’ll keep watching the trends.

Finallly, if you’re a winter sports enthusiast, or just interested in the Sierra snowpack, there is lots of good news. The two upcoming storms are expected to dump from 3-4 feet of snow, and possibly more, above 5 thousand feet in the High Sierra. (Image 11)