October 14, 2018 – Breezy to gusty wind with lowering humidity will lead to increasing fire weather concerns into Monday. Dry with high temperatures above normal through next weekend.
Latest satellite imagery shows an upper level ridge over the eastern Pacific, and an upper trough dropping southward into the Great Basin. As the trough continues to dig southward, a strong surface pressure gradient will develop, which coupled with upper air support, will lead to windy conditions across interior NorCal today into Monday. The MFR-SAC gradient is around 9 mbs this morning, with local gusts of 15-30 mph reported mainly in southern Lake County, the mountains of W Shasta County, northern Sac Valley, and the northern Sierra foothills.
The strongest winds are expected along the western side of the Sacramento Valley, the Sierra foothills, and portions of the Coastal Range. A Wind Advisory is in effect for the west side of the Valley today, as north wind gusts could gust up to 45 mph.
Winds on the east side of the Valley, and to the south will be breezy, but not as strong. In addition, 850 mb charts show a broad area of 45 to 55 mph winds along the Sierra Foothills, with the ensemble situational awareness tool indicating an anomalous easterly wind component.
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As such, a Wind Advisory goes into effect for the Sierra Foothills from this morning into early Monday, with the strongest winds developing in the overnight hours. The combination of winds and lowering humidity will result in critical fire weather conditions.
Lighter northerly flow will continue on Tuesday, but not as breezy as this weekend. Not much change in the overall pattern as a ridge of high pressure remains in place, with dry conditions and above normal temperatures. Forecast highs will be 3 to 7 degrees above normal through midweek. Look for Valley highs in the 80s, and 60s and 70s over the mountains.
Extended Discussion (Thursday through Sunday)
Strong high pressure over the eastern Pacific is forecast to shift onto the West Coast late this week continuing the dry weather pattern with warm days and cool nights.