Strong, persistent West Coast ridge developing; warmer and much drier for most of CA
https://weatherwest.com/archives/12616In the coming days (and probably for the next 2-3 weeks), a persistent ridge of high pressure will set up shop just west of the West Coast–effectively blocking the jet stream and bringing an end to the December parade of cold storms across California. There is strong multi-model ensemble agreement regarding the overall persistence and (more importantly) positioning of this ridge, which will very likely keep most or all of California somewhat warmer and much drier than average for mid-January over the next 2 weeks. 2-week dry spells are not unusual in California, and indeed seem to have a slight climatological preference for the month of January. So this multi-week ridge, in and of itself, is not especially unusual for this part of the world. How long it persists into late Jan, Feb, and beyond is more important from a seasonal and drought-busting (or not) perspective (more thoughts on that below). All in all, though, it appears this will be a prolonged period of fairly benign weather across California and much of the rest of the West. After the December deluge, and enormous Sierra Nevada snow accumulations, this pattern will cause statewide snow water equivalent “percents of average” for the date to fall precipitously–from about 133% of average for the date (as of today) to around or perhaps even below 100% of average for the date by late Jan."