Wind event of the decade in NorCal; dry weather to return

Last week’s storm is now a not-so-distant memory–and some in NorCal are still feeling its effects. There are still as many as 10,000 people who have been without power since Thursday night up here, and some streets are only just beginning to be cleared. In terms of wind damage, the Friday storm was certainly the worst in a decade, and by some estimates the worst since the December 1995 storm. Nearly 3 million people lost power for more than 24 hours during this storm–a pretty impressive number for CA–and tree/structure damage was extensive. Lots of smashed vehicles on tree-lined streets and even a fair amount of structual damage from falling trunks/limbs. Large billboards and some high-tension powerlines came down in many places–even roadside speed limit signs were dislodged. Rainfall was impressive but not of the ten-year magnitude in NorCal, though it would have produced quite a bit more flooding if we had had any rain beforehand. I recorded 8.75 inches for the Thursday-Sunday period, which certainly helps with the extensive rainfall defecits up here. SoCal, despite what it may have seemed like, did recieve more rainfall from this storm than it has in years (some more localized individual rain events certainly brought higher rain totals and more damage in the past 3 years, but the total volume of precipitation produced was less than during this widespread event). Realized rainfall totals in SoCal did reach expected levels for this event–generally 2.5-6 inches along the northern coastal areas and southern mountain areas, 2-4 inches in southern coastal areas and upwards of 10 inches in the mountains. Much of the rain fell at a very moderate rate, which prevented flooding problems from becoming serious and perhaps made for a less “dramatic storm” in some places. Still, this event was a boon to the state’s water supply and should prevent serious water problems from developing during the next 6 months at least. La Nina continues to exert a significant influence on the global circulation pattern, and will contribute to significant Arctic outbreaks over the U.S. in the coming weeks. Here in CA, the weather over the next 1-2 weeks looks benign, especially by comparison. Dense fog is possible inland as the wet ground and a stable atmosphere lead to a moist layer under the inversion, but after Thursday no rain is expected anywhere in the state for a while. The long-range models are indicating a rather warm and dry pattern for the forseeable future. There are two possible exceptions:
1. A cutoff low develops under the ridge or cut off from the mean flow that will be way up in British Columbia. This could bring some chance of precipitation.
2. The retrogressive trough over the Plains States moves far enough west to bring cold Arctic air into the West. This pattern is favored in La Nina years, and is hinted at by the 12z GFS. Keep an eye on it.

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