Heat increases across the region on Friday, smoke and haze persist

September 7, 2018 – No precipitation expected through the extended period. Warming temperatures Friday then back to near normal over the weekend and early next week. Breezy west winds over the Sierra Saturday. Cooler than normal middle of next week. Areas of smoke and haze from wildfires will persist.

Discussion

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A few degrees of warming expected most areas today as the weak trough that went through the Pacific Northwest on Thursday shifts eastward. Light mainly northerly surface gradient this morning will likely bring smoke from Norcal fires southward into the central valley. The Redding airport is showing some smoke at this time and this smoke will likely spread southward during the morning hours. Winds transition to west to southwest this afternoon ahead of next weak trough moving into the Pacific Northwest this afternoon and evening.

Other than smoke associated with NorCal wildfires, skies should remain mainly fair today under southwest U.S. upper level ridge. Light diurnal winds return tonight then return to mainly westerly on Saturday as another shortwave trough tracks through the Pacific Northwest.

Breezy winds are forecast mainly over the Sierra south of Tahoe with gusts into the lower 20 mph range. Overall airmass cools a bit so should see drop in high temperatures Saturday although highs are still forecast to come a few degrees above normal. Brief ridge amplification on Sunday will bring a little warming and lighter winds. A deeper upper trough is forecast to begin digging in over the eastern Pacific starting Monday beginning a cooling trend expected to extend through the coming week.

Extended Discussion (Tuesday through Friday)

The upper trough is expected to continue to deepen along the West Coast next week. High temperatures will likely be in the 80s across the Central Valley, and it wouldn`t be surprising to see some locations only reach the upper 70s. The mountains/foothills will likely be in the 60s to 70s. These forecast high temperatures are 5 to 10 degrees cooler than normal. Locally gusty winds are possible as small impulses move along the deepening trough, especially over the higher terrain. Precipitation will likely remain north of our forecast area through the extended period.