Rain returns to Southern California; enough to help drought?
Monday, February 12, 2018, 16:46 - After a prolonged dry spell, rain is finally on track to return to Southern California and the Desert Southwest. But with the winter rainfall deficit already tipping most of the region into moderate to severe drought, how much help is on the way this week?
Forecasters are watching an area of low pressure and several reinforcing shots of atmospheric energy that are sinking south along the coast out of the Pacific Northwest. These impulses will settle over California for the early part of the week, slowly coalescing into an upper-level area of low pressure off the SoCal coast that will then swing back onshore. There are questions, however, as to how much precipitation the Golden State will actually see courtesy of this system, and how far south it will sink. Here's what you need to know.
- An upper-level atmospheric disturbance will bring some rain and snow to parts of Southern California and the Southwest this week
- Showers, and a few thunderstorms, are expected to move into the central and south coast of California through the day on Monday
- More significant rainfall - as well as heavier snow at elevation - is expected for the Inland Empire, extreme Southern Sierra, and toward the Four Corners
- Unsettled conditions and onshore flow continue through midweek
- Upper-level low expected to bring more significant moisture onshore as it moves in later week, but how far north or south this falls is still up for debate
- Most long-range model guidance suggests low may be too far south, over Baja, to bring much rain to SoCal, but should bring locally heavy rain to Arizona/Four Corners region
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Watch below: Tracking rain and snow this week
February is typically one of the wettest months in California, with Los Angeles collecting an average of 3.8 inches and San Francisco 4.45 inches. Los Angeles typically receives a quarter of its annual rainfall in February, but nearly half way through the month, 2018 isn't exactly going according to plan. LAX hasn't recorded any rain since January 25th, and the last significant rainfall was back on January 9th.
As of February 8th, the Southern Sierra was at only 20 percent of its normal snowpack for the date, and a paltry 13 percent of its usual April end-of-season average. The Central and Northern Sierra aren't faring much better, at 27 percent and 20 percent of their normal snowpacks for this time of year, respectively.
While the details of how much rain will fall locally, and where, are still yet to be seen, generally speaking we expect a 0.25 to 0.5 inches of rain to fall across much of Southern California, with some spots seeing up to an inch. Thunderstorms may also boost amounts over some areas, raising the concern somewhat for the possibility of mud and debris flows.
Light amounts of snow are expected for the Transverse Ranges, generally above 4500 feet, with the highest accumulations falling in the north toward Point Conception.
Models continue to struggle with the longer-range details for late week, but early indications are the heaviest precipitation associated with this upper-level disturbance may swing entirely south of SoCal, driving heavier rains into Arizona by late week and next weekend.
With files from The Weather Network meteorologist Mario Picazo.