re: SoCal Atmospheric River

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Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 154 PM EST Sat Feb 03 2024  Day 2 Valid 12Z Sun Feb 04 2024 - 12Z Mon Feb 05 2024
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF SOUTHERN CALIFORNIA...
...Central to Southern California... The latest models are in good agreement on the evolution of a strengthening cyclone off the central California coast early Sunday as this low pushes northward towards the northern California coast. The strong IVT values that begin to impact the central California coast late day 1, ~1000 kg/m/s, will persist into central California coast range, pushing inland into the northern portions of the San Joaquin Valley and Sacramento Valley and southward into the Transverse Range. Strong inflow and available instability across the area will allow for 1" an hour rain totals, which would be especially problematic where there are burn scars. The probabilities of 8"+ in 24 hours are high enough to introduce a High Risk for portions of the southern CA Transverse ranges. General 3 to 5" areal average amounts likely in both the Transverse and Central California Coast Ranges, with maximum totals just over 10" possible in areas of most persistent training and upslope flow. Modest expansions were made to the Slight and Moderate Risk areas.
For portions of eastern CA near the NV border, including Inyo County/Death Valley, inflow from the Gulf of CA is expected to be more or less unimpeded with 850 hPa winds 40+ kts out of the southeast, setting up a moderate to heavy rain event in the desert. Probabilities of 3"+ in 24 hours is high, particularly in nearby topography where some of the precipitation would be in the form of snow at elevation. The signal was strong/broad enough to lead to some expansion of the Marginal Risk area in that area.

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