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Here’s how bad the Santa Ana winds and fire risk are going to get this week

By in Press Enterprise on December 5, 2017

By Kurt Snibbe

Dry and windy conditions will continue through the week, with the most extreme Santa Ana wind conditions peaking for Orange, Los Angeles and Ventura counties on Thursday, Dec. 7. Northeast winds of 20-35 mph can be expected with gusts exceeding 60 mph over the higher terrain and in the more wind prone areas. Winds will diminish in the afternoon. Humidity will be in the 5-15% range.

The National Weather Service issued a Red Flag alert, warning of wildfire dangers across Southern California through at least Friday. By Saturday, the region will see temperatures in the high-70s to mid-80s.

The image below is from the USDA Forest Service and Predictive Services website called the Santa Ana Wildfire Threat Index that categorizes the threat levels in our region.

The site sawti.fs.fed.us is a result of a recent collaborative effort between San Diego Gas and Electric, UCLA, and the Forest Service. The site allows first responders and the public to zoom in on their area and get updated information regarding fires, wind and surface fuel conditions.

Related: Multiple wildfires burning in Southern California

Tom Rolinski, USDA Forest Service Senior Meteorolgist, compiled the chart below. It shows the average number of days with Santa Ana conditions.

Rolinski said, “The term “moderate to strong” can be defined differently, but here it generally refers to sustained winds of roughly 20 mph or greater. Keep in mind these are average numbers as some years can vary widely.”

Southern California Average Santa Ana Winds per month

Avg. number of days with Santa Ana conditions (dry air and wind gusts):

Sept.:1

Oct.: 6

Nov.: 9

Dec.: 10

Avg. number of days with “moderate to extreme” winds and high fire risk:

Sept.: 0

Oct.: 2

Nov.: 3

Dec.: 3

NASA image of fires

Above: Image from NASA of smoke blowing offshore from fires on Dec. 5.

How the Santa Ana winds strengthen

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