“March Mitigation” commences as unusually cold late-season storm sequence arrives

California Weather Blog –

In my last post, I mentioned that upcoming storms would (finally!) start to chip away at the huge seasonal precipitation deficit that has accumulated this year throughout California–but that this storm series would be far from a “Miracle March.” So far, that expectation has largely been borne out: fairly prodigious multi-foot snow accumulations did occur throughout the Sierra Nevada, and the overall amount of water stored in the statewide snowpack doubled nearly overnight. But it’s important to consider the absolute numbers here: snowpack was so low going into the most recent storm sequence that snow water equivalent doubled from 18% to around 37% of average–meaning that there’s still more than 60% less snow in the mountains than has historically been the case this time of year. More broadly, precipitation to date is still well below average everywhere in California, and is still less than 25% of average across large portions of SoCal. In other words: recent rain and snow have been highly beneficial, but we still have a long way to go.

“March Miracle” still a high bar, but maybe “March Mitigation” is good enough?

Well, I do have some good news to report: there’s quite a bit more rain and snow on the way! A renewed series of storm activity is expected to bring widespread precipitation over (at least) the next 7-10 days, and the potential is there for a rather strong storm or two in the mix. Ensemble forecasts are suggesting that precipitation over the next two weeks could be quite substantial, with several inches possible in some coastal spots and 6 inches of liquid equivalent in the favored Sierra Nevada watersheds. These are not exceptional totals, but they are definitely above average for a two week period this late in the season. Importantly, there will be quite a bit of cold air associated with this precipitation, and so snow levels will once again be low enough for most of this water to fall in frozen form above about 4000 feet (and locally lower). That’s great news from a snowpack perspective, as it appears that this storm sequence could cumulatively drop several new feet of snow in some places (perhaps nearly as much as the last event at the highest elevations).

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