RAIN ON THE WAY TO NORTH BAY. A LITTLE THIS WEEK, MORE LATER?

The pattern change to wetter weather is officially underway across Northern California. Slowly for now with the first real rain arriving on Thursday in the North Bay, and other small storm systems following after that.

THIS WEEK

On Thursday another cold trough dives down the West Coast. (Image 1) This one will be far enough west to give California shot of rain. (Image 2) The models show a band of rain may move through in the morning hours Thursday. (Image 3)

Another storm may be on its heals Friday. (Image 4) But together, the storms will only bring moderate rain to the North Bay, at best. The Canadian model is currenty wettest, (Image 5) while most others keep heavy rain to our north. (Image 6)

LATEST TRENDS

The latest atmospheric signals hint at low pressure troughing coming to the West (good), but also persistent high pressure hanging around in the Northeast Pacific (bad). You can see that set up here. (Image 7) What this does is to keep moisture-rich storms from sweeping into California from the west. Instead, our storms may drop down from the north. Cold, but moisture-starved.

ATMOSPHERIC RIVER HITS PACIFIC NORTHWEST

This set up also favors moisture streaming into the West Coast along frontal boundaries, but they will be directed north of California. (Image 8) That’s happening this week. By the time the moisture stream reaches California, it weakens and splits. (Image 9) But this may change in the 3rd week of March. For that hopeful news, keep reading.

FURTHER AHEAD

Out in “fantasy range” past 10 days, it looks like cold and showery weather will be the norm across California and the West in March. (Image 10) At this point, unfortunately, there are no indications that a true “Miracle March” is in the cards. Instead we may see continual weak and cool storms move in from the north, perhaps even through the end of March. The rain may begin to add up, but not the deluge we had hoped for. Here’s the European weeklies outlook for rain by the end of March. (Image 11)

GEEKY STUFF

Still, as we always say, much could still change. The Madden Julian Oscillation is once again mired in the “circle of death”, too weak, and in the wrong phase for the next two weeks to support strong California storms. (Image 12) By later in March, that could change.

The other teleconnection with a big impact on our weather, the Pacific North American, is in a negative phase (suggests wet for West Coast), which may be one reason we are not completely dry and the PNW is getting blasted with rain. (Image 13)

A POTENTIALLY (WET) HOPEFUL SIGN

For those who perfer to focus on hopeful news, we have a bit of it to share. The Scripps Institution tracks atmospheric river events along the West Coast. Their forecast for the 11th-17th of March is getting a lot of attention. It shows a greater than 80% chance of a (potentially) powerful atmospheric river aimed at California, and one far wetter than is expected at this time of year. (Image 14) This is a long range forecast, and should be viewed with caution. Still, the long range jet stream forecast seems to support the development of the type of zonal flow that would support this AR event. (Image 15)

None of the models are yet factoring it in, but the trend is now being closely watched and we will update you on the potential for the North Bay as the possible event draws nearer.