Brief thread about...snow. As of this weekend, the Southern Sierra now appears to have largest snowpack in recorded history (as measured by snow water equivalent, or SWE). Not just for the calendar date, but for *any* date! #CAwx #CAwater [1/n] 
As I earlier noted was plausible, the "warm" atmospheric river storm on Fri actually *increased* net watershed SWE substantially--partly because it still snowed at high elevations, but also because lower elevation snowpack absorbed a lot of rainwater! #CAwx #CAwater [2/n]
This map plot of the SWE change over the past 24 hours really tells the tale--much snow melting and SWE losses below about 4.5k ft in elevation but large *gains* above that level. Classic "warm-ish" storm dipole pattern! #CAwx #CAwater [3/n]
Snowmelt-amplified flooding has affected multiple smaller Southern Sierra watersheds, but this has so far been much less of a problem elsewhere. Even w/additional warm storm this wk, I expect net SWE will *further increase* despite more lower elev melting. #CAwx #CAwater [4/n]
Mon-Tue flood threat in CA will come mainly from the direct effects of heavy rainfall and very wet antecedent conditions (saturated soils and high river elvels), though there could still be some (smaller) additional snowmelt contribution in some places. #CAwx #CAwater [5/n]
But here, I'm honing in on potential for larger/mainstem rivers to experience more serious flood problems in medium term (i.e., the weeks to come). There is a truly enormous amount of SWE in the southern/central Sierra watersheds... #CAwx #CAwater [6/n]
All that snow is going to melt eventually, most likely starting later in March and into April/May. And California has never experienced such a large snowpack in the context of a several-degree F warmer climate that we now have regionally. #CAwx #CAwater [7/n]
It's impossible to make specific predictions about how severe flooding on Sacramento & in particular San Joaquin systems (as well as tributaries & eastern Sierra watersheds) will be weeks in advance. But this has the potential to be become a big problem by April.#CAwx #NVwx [8/8]
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