Above normal temperatures, smoky sky and breezy winds

August 8, 2018 – Slightly above normal temperatures through the week. Onshore flow increases Thursday through Saturday with breezy winds at times. Smoke from wildfires will continue to impact the air quality.

Discussion

Ridge of high pressure remains in control of the region through Thursday. This will lead to dry conditions, light terrain driven winds, and warmer temperatures. However, smoke from the area wildfires could continue to make for a tricky temperature forecast, and may keep temperatures down by a few degrees. Smoke and haze will continue to impact interior NorCal, with the latest HRRR smoke model showing similar conditions to those experienced on Tuesday.

Poor air quality can be expected, especially near the several ongoing large wildfires. Make sure to check local air quality reports.

A low pressure trough will approach the West Coast Thursday afternoon, acting to tighten the pressure gradient. Local wind gusts 25 to 35 mph can be expected Thursday afternoon into Saturday evening, especially over higher terrain.

This could lead to critical fire weather conditions across portions of the Coastal Range, the northern Sacramento Valley, and the northern Sierra. Thus, a Fire Weather Watch is in effect from Thursday afternoon through Saturday evening.

The trough might help diminish visibility issues due to smoke. In addition to enhanced winds, the trough will bring cooler temperatures across the forecast area, with Valley highs in the 90s. Elevated instability charts suggest that an isolated thunderstorm could develop Friday morning over the southern Coastal range, including Lake Co, as some moisture is advected northward.

However, the latest 00z NAM run is no longer suggesting convection, but will continue to monitor. Dry conditions expected elsewhere.

Extended discussion (Sunday through Wednesday)

Upper ridging from the Desert SW gradually builds over Interior NorCal through the extended forecast period. This will result in above normal temperatures with a slow warming trend through the middle of next week. Slight chance of an isolated afternoon thunderstorm over extreme southern portions of our Sierra Nevada forecast area Sunday and Monday, however best chances look to remain south and east of the CWA.