THE BATTLE OF HIGHS AND LOWS

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In this El Nino winter the weather pattern is not (yet) shaping up to be typical. High pressure is trying to control things along the California coast, sending storms to our north. That pattern looks to continue through mid-December.

SHORT TERM

In the short term a cutoff low pressure system is just off the California coast, and will brush the North Bay Tuesday night into Wednesday morning.

Although it looks impressive, it is rapidly weakening and the weather models have been struggling with how much rain it will bring to the coast. All agree it will just brush the coastal areas of Central California as it weakens and drops south. No rain is forecast further inland.

As of Tuesday midday, the NWS is forecasting a tenth to a half inch of rain in the North Bay by Wednesday afternoon.

Here are the latest model estimates. Let’s go with 1/10 to 1/3 of an inch overnight Tuesday-Wednesday. The rain will drop off rapidly to the east so areas of eastern Lake and Napa counties may be completely dry.

As you can see, there is little room for error. If the low stays further off the coast, we may only get showers in the North Bay. In any case, the showers or rain will likely begin around 9PM Tuesday evening, and end Wednesday morning.

After that, high pressure builds back in. This will push storms north and then east of Central California. A couple of storms that once looked promising for us will drop big rains in Northern California, but not reach us in the Bay Area.

If you are in Crescent City or Eureka there is a lot of rain in the forecast through the upcoming weekend. 250 miles south in Santa Rosa, not so much.

LONG TERM

The jet stream and storm track will be shunted north by our high pressure block through the next 7 days at least.

Out through mid-December, the forecast looks drier than average for most of California except the extreme northwest corner.

WAY in the future, there may be signs of change. Both major long range ensemble models show high pressure finally giving way to low pressure along the coast of California sometime around the 3rd week of December, with increased chances for above normal rain.

Of course, this is out in fantasyland, and consider this just a best guesstimate right now of what could be in the cards for Northern California.

More updates to come.