Strong Santa Ana Winds Could Worsen Southern California Fire Threat Through Friday

Chris Dolce
Published: December 7, 2017

Strong Santa Ana winds in combination with dry vegetation will keep wildfire danger high across Southern California through the end of this week.

Winds gusting up to 80 mph in the mountainous terrain Monday night and early Tuesday caused several wildfires in the region to grow quickly out of control.

Another round of strong Santa Ana winds gusting 50 to 60 mph will impact the mountains and valleys of Southern California into Friday. This will worsen firefighting conditions across the region.

Winds will decrease late Friday but remain gusty, which, combined with dry air, will keep the fire danger high.

(UPDATES: S. California Wildfires)

Dry Start to Wet Season Will Continue

Los Angeles has seen just 0.11 inches of rainfall since Oct. 1, which ranks as the 11th-driest start to the wet season in 141 years of records, according to meteorologist Bob Henson of wunderground.com. That equates to about 6 percent of the average rainfall in the city for the period spanning Oct. 1 to Dec. 4.

Average rainfall by month in Los Angeles increases from November into the winter. The dry season encompasses the summer months when little, if any, precipitation is recorded.

Henson added that San Diego recorded a top-10 driest November with a measly 0.02 inches of rain. That's also its total for the entire wet season, which began Oct. 1.

With such paltry amounts of precipitation and vegetation tinder dry after emerging from the summer dry season, the Southern California region is a tinderbox right now.

Northern California has fared better thanks to some early-season storminess. Downtown San Francisco had received 65 percent of its average precipitation for Oct. 1 to Dec. 4, and Sacramento had picked up 68 percent of its average rainfall for that time.

Unfortunately, the weather pattern is not favorable for any significant precipitation to affect California into at least mid-December.

A northward bulge in the jet stream will keep California dry into mid-December.

A pronounced northward bulge in the jet stream over western North America is now in place and will not erode away anytime soon. When this type of weather pattern sets up and persists, it deflects the storm track northward, leaving California bone dry.

It was a weather pattern like this one that led to a multi-year drought in the state that was finally extinguished last winter.

Whether this pattern remains a persistent feature through the rest of winter remains to be seen, but for now, conditions will remain dry through the first half of December.

(FORECAST: Rainfall Outlook)

A drought outlook from NOAA's Climate Prediction Center calls for drought conditions to persist or expand in Southern California through the winter ahead.

Parts of Southern California are already experiencing abnormally dry or moderate drought conditions, according to the latest U.S. Drought Monitor.


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