INTERAGENCY FIRE WEATHER CENTER PREDICTIVE SERVICES UNIT

 

SATURDAY, SEPTEMBER 24, 2016

SOUTHERN CALIFORNIA GEOGRAPHICAL AREA COORDINATION CENTER

RIVERSIDE, CALIFORNIA

***Strong offshore winds across Southern California tonight through Monday afternoon***

***Hot and very dry Sunday and Monday***

 

Strong high pressure aloft off the California Coast will bring significant warming to the region through Monday. Maximum temperatures will be in the 70s to low 80s across the mountains and mid 80s to mid 90s in the valleys today. Temperatures will warm to the mid 70s to mid 80s across the mountains and mid 90s to 105 in the valleys Sunday and Monday. Minimum humidity will be mainly between 12% and 25% today and then drop into the single digits and teens Sunday and Monday. Surface high pressure currently over Oregon will bring local northerly winds of 10 to 20 mph with gusts to 35 mph to the Central Coast, Santa Barbara County, mountains of Ventura and Los Angeles Counties, and the Owens Valley through this afternoon. The surface high will shift into the Great Basin tonight and strengthen bringing northeast to east winds of 20 to 40 mph with gusts to 60 mph to the mountains and below the canyons and passes of Southern California through Monday afternoon. These offshore winds will weaken substantially Monday night, but there will still be some gusty winds across Southern California through Tuesday afternoon. A weak area of low pressure will move over Southern California from Baja bringing cooling and an increase in humidity to the region Tuesday and Wednesday. Isolated showers and thunderstorms will be possible south and east of Los Angeles County Tuesday and Wednesday. There will be further cooling late next week as a Pacific trough drops down the West Coast. This trough will also bring gusty westerly winds to the mountain ridges and desert passes late next week.

 

There will be an elevated threat for large fire across the region today as temperatures warm to above normal and humidity becomes low. The best threat for large fire will be over the Central Coast and over the mountains of Ventura and Los Angeles Counties where there will be locally strong and gusty northerly winds. There will be a high risk for large fire across much of Southern California away from the Southern Mountains Sunday and Monday due to very strong offshore winds along with humidity in the single digits and low teens. Rapid rates of spread and long range spotting will occur if an ignition gets started in one of these windy areas. The Southern Mountains received substantial rainfall early this week, so the threat for large fire will be much less across this PSA then the rest of Southern California. Across Central California, the potential for large fire will remain elevated due to hot and very dry conditions Sunday and Monday. A new fire will be able to burn actively at night due to poor humidity recovery through Monday night. The large fire threat will decrease significantly starting Tuesday as winds lighten, humidity increases, and temperatures cool. Expect heavy initial attack activity Sunday and Monday, otherwise expect light to moderate IA activity through the end of next week.

 

For addition fuels and weather information, including the Santa Ana Wildfire Threat Index, please visit:

 

http://gacc.nifc.gov/oscc/predictive/weather/index.htm