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August 16, 2018 – Near normal temperatures today, warming to above normal Friday into Saturday, followed by minor cooling Sunday into early next week. Dry weather expected with continued smoke impacts from wildfires.

Discussion

Short wave trough off the NW CA coast will slowly lift into OR over the next 24 hours as upper ridging from the Desert SW begin to build toward NorCal. Delta breeze has remained strong overnight, but marine layer as decreased significantly in depth. Don’t expect any stratus into the Southern Sac Valley this morning, but rather to remain confined to around the Carquinez Strait.

High temperatures today forecast to be similar to Thursday, except slight warming in Delta breeze influenced areas as onshore flow trends weaker. Heights/thicknesses increase Friday into Saturday as short wave upper ridging from the EPAC moves through.

Max temps warm 5 to 9 degrees above normal with triple digit heat expanding over the Northern Sacramento Valley. Remainder of the Central Valley forecast to see upper 90s Fri/Sat with mainly 80s to 90s for the mountains and foothills. Upper low progged to develop offshore then move into the PacNW Sunday. Associated troughing lowers heights over Interior NorCal and increases onshore flow. Minor cooling results with high temperatures lowering back to near to slightly above normal.

Extended Discussion (Monday through Thursday)

Warm and dry weather is in store for the extended forecast period. Norcal will remain under relatively stable southwest flow aloft between upper level high pressure over the southwest U.S. and troughing over the eastern Pacific. Therefore, expect any afternoon thunderstorm development to remain well east and south of the forecast area.

Although main ridge axis will remain over the rockies next week, airmass remains warm enough for a little above normal temperatures throughout the extended period.

Except for the thermally induced delta breezes, winds through the extended period should remain relatively light under the upper ridge.