October 2, 2017 – Cooler weather with breezy north winds early this week. Lighter winds late in the week with warming temperatures. Slight chance for showers along the northern Sierra crest late Tuesday.
Clear skies across interior NorCal early this morning as the West Coast trough continues to evolve. Current temps range from the mid 20s to mid 30s in the mountain valleys to the mid 50s to mid 60s in the Central Valley.
MFR-SAC gradient remains around 11 mbs and RNO-SAC is up around 4 mbs resulting in breezy north to northeast winds gusting 30-40 mph along the west side of the Sacramento Valley, across the higher terrain of Lake County and across the higher elevations of the northern Sierra Nevada. KDAX VWP still indicating 50-55 kts from 1-3K ft associated with the barrier jet set-up along the western edge of the Sacramento Valley.
Red flag warning and wind advisory continue and satellite imagery is picking up the heat signature from a new wildfire in the valley to the northwest of Sacramento that began late Sunday evening.
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Water vapor imagery shows the large area of darkening (strong subsidence) moving south through the region currently. Winds may decrease somewhat today as this feature moves south and upper level support weakens, but it will still remain breezy for many locales.
Below-average temps will continue today and Tuesday before milder temperatures return beginning mid-week. Very slim chance for a few showers along the northern Sierra crest late Tuesday afternoon and evening as the closed low develops west of Tahoe.
Extended discussion (Friday through Monday)
Dry conditions expected for the end of the week through the weekend as high pressure builds over the area. Temperatures will warm to several degrees above normal by the weekend with valley highs in the mid 80s and 60s-70s for the mountains. Northerly winds will return but look to remain light at this time.