SACRAMENTO, Calif — A Bomb Cyclone with an atmospheric river has hit the west coast. Moving from Washington to northern California Wednesday. The Bomb Cyclone, rapidly intensified over the last 24 hours with a pressure drop of more than 24mb. In fact, it more than doubled its drop in pressure, with 56 mb in 18 hours.
Rain begins Wednesday morning with snow developing during the afternoon. Snow level is initially below the passes, but as the warmer part of the storm presses toward the coast the snow level will rise above the passes Thursday.
Computer models are showing rain totals potentially between 1 and 4 inches of rain from Wednesday through Saturday. There is a sharp drop off in rain totals south of I-80 with some places barely getting any rain on Wednesday.
The Coast and parts of the Sacramento Valley are under a Flood Watch through early Saturday. Minor rises on creeks, streams and rivers could result in some low level flooding. Also, be aware of clogged storm drains that could produce roadway flooding.
The storm will have heavy snow to begin the cycle on Wednesday, then warmer air will get pulled in. This will make the snow level rise and bring rain to the mountain passes for part of Thursday and Friday before cold air lowers the snow to the passes and below for Saturday and Sunday. A Winter Storm Warning is in effect through Wednesday evening. Expect many changing conditions in the Sierra.
Along with the heavy rain and snow, comes wind. A Wind Advisory is in effect Wednesday for parts of the Sacramento Valley and Coast. Gusts in the high country will also be significant, at times over 50mph.
Here is a look at our Weather Impact Alert for Northern California. The timing will start Wednesday and run through Monday. Impacts include heavy rain and snow as well as periods of gusty winds. This will impact pre-holiday travel this weekend.
This is looking to be a long-duration active storm cycle, with the potential of big valley rain and Sierra snow from multiple atmospheric river-driven storms lasting into early next week.
Rain chances extend into next week including Thanksgiving, but more time is needed to provide details and confidence in this time period.
Continue to keep an eye on the extended forecast.
TONIGHT: Rain with periods of moderate to heavy precipitation. Valley lows in the 50s. Lake Tahoe lows in the 30s with rain moving up in elevation overnight. Weather Impact Alert Day
THURSDAY: Mostly cloudy with a chance of showers. Highs in the low to mid-60s. Lake Tahoe highs in the low 50s with a chance of showers. Weather Impact Alert Day.
FRIDAY: High chance of rain with a chance of thunderstorms. Highs in the lower 60s. Lake Tahoe highs in the lower 50s with a chance of showers. Weather Impact Alert Day
SATURDAY: Chance of rain with valley highs near 60°. Lake Tahoe highs in the lower 40s with a chance of showers. Weather Impact Alert Day
SUNDAY: Cloudy with a chance of showers. Highs in the upper 50s. Lake Tahoe highs in the low 40s with a chance of showers. Weather Impact Alert Day
MONDAY: Chance of rain with highs in the mid to upper 50s. Lake Tahoe highs in the mid-30s with a chance of snow. Weather Impact Alert Day.
TUESDAY: Decreasing chance of showers with highs in the mid to upper 50s. Lake Tahoe highs in the low 30s.
WEDNESDAY: Slight chance of showers otherwise partly Sunny. Highs in the mid 50s.
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