Models Agree: Big Rain Totals, High Winds Inbound

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A classic North Bay winter storm is inbound late Friday, and all computer models agree that this one will pack a wet and windy punch.

By late Friday, the impressive comma-shaped low pressure center was nearing the coast.

The intense low pressure center was also pulling in a lot of moisture from north of Hawaii (in blue).

The southerly flow ahead of the front is a classic recipe for a period of high rain rates as the cold front moves through late Friday or early Saturday. So expect moderate to heavy rain at times late Friday afternoon into early Saturday, and winds gusting to 40mph or more. Then late on Saturday, a second front will come through, enhancing rain rates once again.

How much rain can we expect in the North Bay? The latest high resolution models agree that totals may approach or even exceed 5 inches in the hills, and average 2-2.5 inches in the valleys of the North Bay. Places like Santa Rosa, Windsor, Petaluma and Healdsburg should be between 1.5 and 3 inches by Monday.

The WRF model shows the mountains of northern Sonoma and southern Lake Counties in the bullseye of heaviest rain. These totals are through early Sunday.

Meantime, the NAM model is even wetter, with totals of up to 8 inches in the mountains of the North Bay. That may be a bit high however, as the model trends by late on Friday were to pull back a bit on rainfall totals.

If you’re headed to Tahoe this weekend, expect chain controls with snow levels ranging from 6-7 thousand feet. And 1-3 feet of snow at the pass levels of highways 80 and 50, as well as above 7 thousand feet at the ski resorts.

The rain will continue on Sunday, as the low pressure center moves through and gives us a final shot of rain.

For the Kincade burn area, a Flash Flood Watch is in effect from Friday at 4PM, until Saturday at 4AM due to the high rain rates expected, and the possiblity of flash flooding and debris flows.

Looking past this weekend, our weather may turn dry for around a week or so. A few weak storms may move through to our north, but high pressure should bring pleasant weather.

However by the third week of December forecast models are hinting that our weather may again turn wet, with a low pressure trough parked along the California coast.

But, that’s quite far into the future and much could change. For now we’ll enjoy another weekend of much-needed rain across all of Northern California.