June 26, 2018 – Dry this week with high temperatures ranging from just below to slightly above normal. Hot weather returns again this weekend with breezy northerly wind and lowering humidity.
Minor warming expected today over Interior NorCal as heights and thicknesses increase. Moderate to strong flow will continue through the Delta, however the marine layer depth has decreased to around 1100 feet. Thus cooling into the Central Valley will be limited today. Highs this afternoon expected in the mid 80s near the Delta with 90s in the Central Valley and 70s to low 90s for the mountains and foothills.
Heights lower Wednesday into Thursday as deepening upper troughing in the EPAC moves inland. This will increase onshore flow, deepen marine layer and provide some synoptic cooling to Interior NorCal. Strong Delta breeze will bring enhanced cooling into the Central Valley. High temperatures Wednesday into Thursday expected to lower to near or slightly below normal. Breezy southwest wind will be possible over higher mountain terrain but forecast remains dry.
Upper trough shifts east Thursday night then EPAC High builds inland Friday into the weekend. This will result in significant warming with triple digit heat returning to the Central Valley Saturday. Breezy northerly wind develops over portions of Interior NorCal by early Friday and persists into the weekend with lowering humidity.
Extended discussion (Saturday through Tuesday)
The upper trough shifts eastward into the northern Rockies as high pressure builds over the eastern Pacific. This will likely result in hot and dry conditions, along with breezy north winds not dissimilar to what we experienced this past weekend. We will be monitoring fire weather conditions closely during the Friday-Saturday time period. Temperatures will likely exceed the 100 degree mark across much of the Central Valley this weekend.
Modest cooling is currently projected early next week as a weak trough passes through the Pacific Northwest.