Locally breezy winds today, some cooling on Tuesday

August 3, 2020 – Dry and seasonably hot weather continues across the region today. Cooling returns Tuesday.

Discussion

Clear skies cover the region early this morning. IR difference imagery shows a lack of stratus along the coast, and profiler data indicate the marine layer is very very shallow. Winds are generally light except for a light to moderate Delta Breeze continuing at Travis AFB. Current temperatures are similar to 24 hours ago over most of the area and range from the 40s in the colder mountain valleys to the mid 60s to mid 70s across the Central Valley.

Little change expected in the seasonably hot and dry pattern today. Highs across the Central Valley will once again be in the upper 90s to slightly above 100.

Heights aloft forecast to drop slightly beginning Tuesday as weak closed low pinches off along the northwest California coast, then lingers Wednesday before another short-wave reinforces the West Coast trough on Thursday.

Onshore flow is expected to increase Tuesday and Wednesday as the marine layer deepens, beginning the cooling process inland. Delta Breeze influenced areas are forecast to be around 10 degrees cooler Tuesday compared to today, while the north end of valley won’t see much cooling until Wednesday. May see some stratus work its way inland into the Sacramento area Wednesday morning.

Thunderstorm chances are expected to remain mostly to the north and east of the region the next several days, though an isolated storm or two may be possible late Wednesday across far northwest Shasta County.

Wildfire smoke possible at times across the region the next few days, especially north of Sacramento. Onshore flow expected to bring considerably higher humidity inland by Wednesday and Thursday.

Extended Discussion (Friday through Monday)

Ensembles indicate upper level trough beginning to break down over NorCal Friday into the weekend as high pressure builds back in over the south. This will cause onshore flow to weaken, temperatures to rise, and humidity to fall for the weekend.

Temperatures Friday will warm slightly around 1 to 5 degrees, though they will still be near or slightly below normal in the upper 80s to upper 90s for the valley and upper 60s to upper 80s for the mountains and foothills.

Temperatures rise another 2 to 5 degrees for the weekend and early next week with Valley highs in the mid 90s to 103 and 70s to 90s in the mountains and foothills. Although onshore flow will be weaker than midweek, a moderate Delta Breeze will remain in the nights which will keep morning lows mild.