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August 24, 2018 – Cooler and dry weather expected through the week. Gusty winds could bring critical fire weather conditions to the Sierra Sunday. Areas of smoke and haze will continue, especially near wildfires. Fire Weather Watch from Sunday afternoon through Sunday evening for Northern Sierra Including Lassen NP and Plumas and Lassen NF/S West of the Sierra Crest (West of Evans Peak-Grizzly Peak- Beckworth Peak)-Northern Sierra Including the Tahoe and ElDorado NF/S West of the Sierra Crest-Stanislaus NF West of the Sierra Crest.

Discussion

Conditions are looking favorable for some marine stratus to develop as we head towards daybreak. The current marine layer depth is between 2500 and 3000 feet and we are seeing gusty winds 25 to 30 knots at SUU. This should give the Sacramento area a decent shot at some patchy marine stratus during the morning. Any stratus will burn off quickly during the mid morning with sunny skies prevailing. A trough will be tracking through the PacNW and that will continue to keep temperatures on the cool side below normal but they should be a few degrees above what we saw on Thursday. Onshore flow will continue and we should see a Delta breeze by the evening once again.

A weak ridge builds in for Saturday and that will warm things up to near average for this time of year. A stronger trough will then dig into the PacNW and the Great Basin on Sunday and Monday. This will bring cooler temperatures with high temperatures running 5-12 degrees below average. The bigger impact will be gusty west to southwest winds. A 25-35 knots 700 mb jet will develop and this will bring wind gusts 25-30 knots in the Sierra with local gusts 35-40 knots on the highest peaks during the afternoon and evening Sunday.

The gusty winds and very dry fuels will cause elevated fire weather conditions and a fire weather watch is in effect for the Sierra on Sunday. Weaker winds are expected on Monday as the tough pushes to the east but temperatures will remain on the cool side. Areas of smoke of haze will continue, especially near wildfires, though some general; improvement is expected with onshore flow.

Extended Discussion (Tuesday through Friday)

Cooler weather on track for mid to late next week as upper level low pressure system is progged to pass over NorCal. Afternoon high temperatures across the region will range between 5 and 10 degrees below normal through Thursday. A shortwave ridge of high pressure may bring warming conditions late next week, but afternoon highs will still be on the cooler side of normal. No precipitation is expected at this time.