![]() Not just for the calendar date, but for *any* date! #CAwx #CAwater /FYmFXqs2yL- Daniel Swain March 12, 2023Īnother moderate to strong atmospheric river Mon-Tue may produce “outsized” flood and wind impacts due to extremely wet antecedent conditions As of this weekend, the Southern Sierra now appears to have largest snowpack in recorded history (as measured by snow water equivalent, or SWE). Additional isolated severe storms are possible this afternoon, posing hazards in their own right but also keeping soils saturated ahead of the next big storm.īrief thread about…snow. ![]() Yesterday, several areas of thunderstorms developed in the Central Valley, including isolated true “supercell” thunderstorms that ultimately produced damaging large hail, flash flooding, and at least one confirmed tornado in the Central Valley and lower Sierra foothills. The “break” between storms in NorCal has been anything but in some localized spots.Although this record SWE will most likely not contribute substantially to flood risk this week, I am becoming increasingly concerned what it may imply regarding flood risk from late March through April or May. These snowpacks will likely grow yet more this coming week–exceeding all-time record levels by an even wider margin. Despite lower and middle elevation snowmelt, the addition of new high elevation snow and absorption of rainwater by the snowpack at middle elevations has resulted in what appears to be a new record regional snowpack (in terms of SWE) for the Southern Sierra, and possibly also for the Central Sierra.Widespread and locally serious flooding occurred in the Southern Sierra watersheds ( including Kern and Tulare watersheds) as well as in the agricultural centers of Monterey/Santa Cruz Counties (especially the community of Pajaro, near Watsonville, that has been completely inundated by rising waters caused by a nearby levee break on the Pajaro River). A “Pineapple Express”-type atmospheric river brought very heavy precipitation (heavy low-mid elevation rain, including atop an existing snowpack in many places, and extremely heavy high elevation snow) to central California. ![]() But what has transpired in the past, oh, 48 hours or so? Well: After a long period (a full season, really) of different kinds of exceptional weather conditions all around California, there’s yet one more big storm to come in the immediate future (discussed below). 0 Comments Wild times in the California weather world.
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