TWO STORMS INBOUND FOR FIRST WEEK OF NEW YEAR

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THE BIG PICTURE

Two weather systems are inbound to Northern California this week, with the first storm potentially wetter, and the 2nd storm colder. Neither storm will be major, but both will bring us beneficial rainfall, with snow in the Sierra.

The forecast models disagree about the longer range pattern.

SHORT TERM FORECAST

You can see the storms lined up in the North Pacific. The first storm will arrive across the North Bay Tuesday afternoon (the 2nd) with showers continuing through much of Wednesday. After a several day break, the 2nd storm system will drop in from the north on Saturday the 6th.

Clouds will overrun the North Bay by early Tuesday, but the rain should hold off until afternoon. This storm is headed in from the west, and over water, and so should pick up enough moisture to give us a nice rainfall.

(You can also see strong high pressure building in following the storm. This will impact our next system out to the west)

The Tuesday-Wednesday system should bring us about one half to a full inch of rain (a bit more in the hills) by the time it winds down Wednesday afternoon.

The European forecast below is one of the drier outlooks.

LONGER RANGE FORECAST

Thursday and Friday should be dry and sunny as the strong ridge of high pressure that we mentioned builds back in over the ocean northwest of California.

As we mentioned, this big high pressure system will impact our next storm for Saturday. Instead of approaching from the west this one will be forced north, and drop down to California over land. You can see the jet stream forecast as high pressure sends the storm track north, before plunging south.

This track over land, and not the ocean, will keep the Saturday system from picking up much moisture. So it should be drier but also colder than the first storm. Here it is on the European model forecast, dropping into California from the north on Saturday

The Saturday storm will be forced far enough east that it will just brush us in the North Bay. Because of that, projected rainfall amounts from Saturday-Sunday are light.

OUT IN THE FANTASY RANGE

Looking even further out, the forecasts are all over the place. For the first time this winter the Pacific North American pattern is forecast to turn negative. What that usually means is a low pressure trough and storminess for the West Coast, which is promising.

While both major models DO show low pressure over the West during the 2nd week of January, the GFS model shows it pushing further west, which would allow storms to sneak into California from the ocean….a potentially wet pattern. And, the model is showing above average rain for the 2nd week of January.

Meanwhile the European model is drier, showing the same low pressure trough setting up further east. Just a few hundred miles that could make a huge difference in the amount of rain we get.

This setup would keep storms from reaching us from the west (over the ocean). Not surprisingly, the Euro shows a drier than average 2nd week of January.

Which model will win out? We’re pulling for the wetter GFS forecast.

Of course all of this is way out in the future, which means the forecast can and will change in the coming days. We’ll keep you up-to-date on how all of this impacts the North Bay. Stay tuned!