October 13, 2018 at 9:55 AM Update: The National Weather Service in Sacramento has issued a Red Flag Warning, which is in effect from 11 PM this evening to 11 PM PDT Monday. The Fire Weather Watch is no longer in effect.
October 13, 2018 – Breezy to gusty wind with lowering humidity will lead to increasing fire weather concerns this weekend into Monday. Dry with high temperatures above normal through next week. Fire Weather Watch is i effect from late tonight through Monday morning.
Discussion
Satellite imagery and model analysis indicate dry NE flow aloft between upper ridging over the eastern Pacific and a closed low off the SoCal coast. Dry weather will prevail today, with daytime temperatures today will be 5 to 9 degrees above normal. Main concern during the short term period is the increasing north to east wind this weekend, and the associated fire weather concerns. A surface high pressure will build into the Great Basin, leading to an enhanced surface pressure gradient.
Breezy winds will develop this afternoon, mainly from around Chico northward. Winds will become more widespread Saturday night into Monday morning as pressure gradient increases. The strongest winds are expected along the western side of the Sacramento Valley, the Sierra foothills, and portions of the Coastal Range. Latest guidance suggests that wind speeds could approach wind advisory criteria. The combination of gusty winds and low humidity will likely lead to critical fire weather conditions. Thus, a Fire Weather Watch remains in effect from Saturday night into Monday morning. Winds will decrease slowly by Monday afternoon as pressure gradient relaxes. Dry conditions and above normal temperatures will continue through early next week, as upper ridging remains in control. Forecast highs will be in the 80s across the Valley, with 60s and 70s over the foothills and mountains.
Extended Discussion (Wednesday through Saturday)
Upper ridging from the eastern Pacific extends inland along the West Coast next week with dry conditions continuing for interior NorCal. Highs will be about 5-10 degrees above average with 80s in the Central Valley and generally 60s to 70s for the mountains.