After a crushingly dry February, it looks as if early to mid-March is likely to bring California some of the serious moisture it needs from the 2015-16 El Niño event--and perhaps some unwanted flooding and mudslides. Long-range models are increasingly confident that the low-latitude jet stream that’s been dodging the California coast for weeks will finally plow into the state over the next 10 to 15 days, hauling copious amounts of Pacific moisture inland with it. The last few runs of the GFS and ECMWF models have become especially bullish on the development of one or two atmospheric rivers (ARs) heading into California over the next week or two. Roughly 30% to 50% of annual precipitation in the West Coast states occurs from just a few AR events per year.
The first significant storm should plow into northern and central California this coming weekend, followed by a stronger series of storms affecting most of the state during the following week. The 0Z Wednesday operational run of the GFS model doused parts of the central and northern California and Sierra Nevada with 10” to 20” of precipitation over the ten-day period ending at 7:00 pm EST Friday, March 11. The GEFS and ECMWF ensembles, though less dramatic than individual runs, still paint a very wet picture for the state. It remains unclear how far into southern California the biggest rains and mountain snows will extend. The outlook for very heavy precipitation is a bit more confident from central California all the way north to Washington. Already, some California reservoirs arereleasing water: though this may seem odd while the region is still in drought, it’s a long-employed strategy to help reduce the odds of flooding when torrential rains are predicted....MUCH MORE