August 7, 2020 – Warming trend through the weekend, turning above normal by Saturday. A slight chance of mountain thunderstorms from Friday into early next week.
Discussion
Upper trough continues to weaken with diminishing onshore flow allowing for warming trend, temperatures will warm back to near normal levels today. Highs will be in the lower 90’s over the Cent/Southern Sacramento Valley, Northern San Joaquin Valley and Delta and upper 90’s Northern Sacramento Valley. Weak low splits off main flow near the Bay Area today, as main jet flow relocates over the Pacific Northwest. This low will bring just enough moisture northward over the Sierra for a few isolated thunderstorms near the crest mainly south of Interstate 80. Low drops south off the SoCal coast Saturday and Sunday with isolated mountain thunderstorm chances shifting a bit south, mainly south of Highway 50. Weak upper low pushing into the eastern Pacific Monday may push moisture farther northward for a little better isolated thunderstorm coverage, but confidence is low.
Rising heights and diminishing onshore flow Sat-Mon will allow temperatures to warm to above normal levels with moderate heat risk possible over the northern Sacramento Valley. Especially due to warm overnight lows from the upper 60’s to low 70’s. Highs Saturday-Mon will be 97 to 107, warmest Northern Sacramento Valley.
Extended Discussion (Tuesday through Friday)
Ensembles maintain weak broad weak trough pattern along the West Coast later next week.
Temperatures will be close to average for mid-August. Moisture/instability expected to remain mainly east of the Sierra Nevada crest.