While the biggest weather story of the week is undoubtedly the blockbuster snow affecting western New York, there's an equally rare phenomenon occurring on the other side of the country: it's raining in California, and more could come as we head into the winter.
The rain will arrive in two waves, with both batches of precipitation coming ashore ahead of low pressure systems approaching the Oregon coast. The first wave is hitting right now, with the second slated for arrival on Saturday.
It's not much rain—Eureka has seen about 0.36" so far—but people in drought-stricken areas from Washington California will take what they can get. The latest quantitative precipitation forecast (QPF) from the Weather Prediction Center shows seven-day precipitation totals of one to three inches from the Bay Area north to the Oregon state lines, with higher amounts expected north through British Columbia. Keep in mind that precipitation will fall as snow at higher elevations.
This region of the United States is still in an "exceptional drought," with year-to-date rainfall deficits running five to fifteen inches below normal, not to mention rainfall deficits from previous years. While this week's meager rainfall totals are just a drop in the tipping bucket compared to what the area needs to recover from the damage, any little bit of rain helps.
The good news for California is that we're approaching the rainy season, as almost all of the region's normal rainfall occurs during the winter and spring. The Climate Prediction Center released its latest three-month precipitation outlook this morning, in which the agency's experts predict that a good chunk of the United States from California to the Megalopolis has slightly higher-than-normal chances of seeing above-average precipitation during the December/January/February time frame.
Also of note is that the precipitation chances that the CPC draws on its map looks like it could be straight from a textbook's section on wintertime El Niño rainfall patterns in the U.S. At the beginning of the month, the agency posted a 58% chance of an El Niño developing this winter. Precipitation from these equatorial Pacific warming events tend to drench parts of the West Coast, though it is by no means a sure thing.
[Images: Intellicast, WeatherBELL, Drought Monitor, author]