From Watts Up With That?
Satellite view of the Northern Hemisphere over the Pacific Ocean show the “bomb cyclone” off the California coast at 11:30AM PST. Credit: NOAA-NESDIS GOES-18 Satellite GeoColor Composite
A major winter storm, with winds gusting up to near hurricane strength is moving towards northern California. Dubbed a “bomb cyclone” due to rapid central pressure drop, it more than qualifies for the 24 millibars (mb) in 24 hours “bomb” cyclone designation.
As of 11AM Wednesday Jan 4th, the central pressure of the storm as it was just off the California coast was 28.33 inches (959.36 millibars) as seen in the graphic below. That pressure is lower than the centrral pressure of many hurricanes.
Image from Windy.com
The National Weather Service (NWS) has produced forecasts for areas of likely flooding that covers much of the Sacramento Valley and the north coast.
Because this winter storm is relatively warm, snow levels are averaging higher, causing rain to fall on snow-laden areas, creating snow-melt which will overwhelm already waterlogged soil, making for fast runoff into creeks and rivers.
Image: NWS Sacramento
The NWS has issued a Winter Storm Warning for the Northern Sierra Nevada.
Heavy snow expected. Total snow accumulations of 4 to 10 inches, except 6 to 18 inches west of Highway 395. Lowest valleys below 4000-4500 feet elevation are only expected to see up to 3 inches of snow.
Snow levels will start off below 4000 feet before briefly increasing to 5000-6000 feet Wednesday afternoon. Snow levels will then fall again to 4500-5000 feet Thursday. This storm will come in 2 parts, and areas east of Highway 395 may see a brief break Wednesday evening.
For the areas Near lake Tahoe, the NWS advises the situation is even worse:
Heavy snow expected. Total snow accumulations of 8 to 14 inches, except 1 to 2 feet above 7000 feet. Localized amounts up to 3 feet are expected for the Sierra crest. Winds gusting as high as 100 mph over Sierra ridgelines with gusts up to 40 mph in the Tahoe Basin.
In addition, widespread damaging winds are forecast from this winter storm.
Image: NWS Sacramento
Winds on the valley floor are expected to gust as high as 60 mph, with higher elevations seeing stronger wind gusts.
Dr. Ryan Maue had this to say on Twitter:
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