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December 6, 2020 – Areas of gusty north to east wind develop later today and persists into early Tuesday. Dry weather expected through the week with above normal high temperatures.

Discussion

Weak frontal system moving across far northern portions of CA attm with mosaic 88-D showing a few light returns north of our CWA. Temperatures currently running warmer in most areas, but could still end up with some patchy frost in the Central Valley this morning. Some haze/mist also being reported at a few of the observing sites in the Central Valley.

Frontal system digs into the Great Basin today as upstream EPAC ridging begins to build inland. This will result in locally breezy northerly wind developing this afternoon, becoming more widespread tonight into Monday. Strongest wind in the Sacramento Valley expected along the southern west side, extending into the Delta area.

Wind advisory has been posted to cover this. Remainder of the Central Valley looks breezy, but below advisory criteria tonight into Monday. Locally strong wind possible in the higher elevations, over ridges and through favorably oriented canyons.

Elevated fire weather concerns may be possible in some areas during this period. High temperatures today expected to be slightly lower than Saturday, but remaining above normal.

Increasing subsidence and downslope flow will result in some warming over interior NorCal Monday. Breezy to locally windy conditions persist with pressure gradient trending down Monday afternoon into evening.

Locally gusty easterly wind continues in the eastern foothills and mountains Monday night into Tuesday morning as EPAC upper ridging builds farther inland. Upper ridge axis shifts through on Tuesday, which looks to be the warmest day of the week. Could see the mercury climb into the low 70s for some areas in the Central Valley/Delta Tuesday. Heights fall Tuesday night into Wednesday resulting in minor cooling as short wave trough moves into the PacNW.

Extended discussion (Thursday through Sunday)

No major changes to the forecast as models and ensembles continue to support ridging along the West Coast. We may have periods of occasionally breezy north flow mid to late week, as guidance also suggests downstream troughing over the Desert Southwest. Overall, expect the warm days and cool nights to continue.