FIRST WEAK STORM IN VIEW! MORE (POSSIBLE) ON THE HORIZON.

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After a 30-plus day dry spell, the first small storm for California has finally come in view of mid-range forecasts. And, multiple teleconnections and long range trends suggest this subtle shift may herald an extended period of cool, more blustery weather. Finally….

CURRENT

For now, near record heat holds sway over the North Bay and Northern California, and in fact unusual heat extends north almost to Alaska (Image 1) as high pressure hugs the West Coast. (Image 2)

THE MJO

But, changes are already underway. The Madden Jullian Oscillation has emerged in the Indian Ocean, and looks to stay there for at least two weeks. (Image 3) The trend line is in green.

If you follow this blog, you know this can have enormous, positive downstream effects on the West Coast, supporting low pressure troughs and storminess.

THE PNA

Supporting this trend is the Pacific North American pattern, which is forecast to go negative, and stay there, after mid-February. (Image 4)

The green line is the one to watch. Without getting into too much detail, this also supports a return to storminess for California.

Here is a generalized view of the pressure set-up associated with positive and negative phases of the PNA. (Image 5)

The PNA was strongly positive in both November and January, helping to explain our bone dry weather in those months. But in December, it went strongly negative as our weather turned stormy, and that’s what we currently expect to happen in the coming weeks as well.

THE OUTLOOK

So, here it is. By the 15th, the first small storm will arrive. Maybe some snow in the Sierra, but most everything will stay east of us here in the North Bay. (Image 6)

But, low pressure will have made its first push back into the West. (Image 7)

Better news. By the 22nd (Image 8), and the 27th (Image 9) the big high pressure dome is forecast to retreat toward Alaska, allowing low pressure to press into California.

A few small storms may be able to reach us from around February 20th-28th. (Image 10)

MARCH

Yes, we know. Slow progress. But all atmospheric signals suggest that more, and bigger storms may follow as March arrives. In fact on March 15th, long range forecasts show low pressure still controlling weather over California. (Image 11) And the European outlook sees quite a bit of snow for the Sierra by then. (Image 12)

Is all of this certain? Of course not. But there is strong model and teleconnection agreement, and that’s as good as we can get at this point. The European weeklies (Image 13) and the CFS (Image 14) both show rain returning to normal around the end of February, and then ramping up by mid-March.

We know. A long way in the future. But there are lots of reasons to be optimistic that, if not a “Miracle March”, then at least a fairly wet one is shaping up. We’ll keep you updated on the impacts to the North Bay.