Warm and dry weather this week. Locally breezy at times in the Delta and mountains. Strongest winds will be in the afternoon & evening hours, especially tomorrow, with gusts up to 25-35 mph.
Discussion
Clear skies cover interior NorCal early this morning. IR difference imagery shows stratus still packed in along the coast, and profiler data indicate the marine layer has deepened slightly to between 1.5k and 2k ft. Surface pressure gradients continue to trend a little more onshore, and the Delta Breeze has returned with gusts around 25-30 mph presently at Travis AFB. Current temperatures are mainly down slightly compared to 24 hours ago, especially in areas influenced by the Delta Breeze.
Upper ridge will be nudged east the next few days as the developing trough over the eastern Pacific moves into the PacNW. The result will be cooler temperatures (about 5-10 degrees lower compared to Sunday and Monday’s) as highs return to around average for late-September today through Thursday.
In addition to the cooler weather, breezy west to southwest winds are expected in the Delta region and over the Sierra each day, strongest on Wednesday with gusts up to 25 to 35 mph.
Ridging, and northerly surface flow, returns behind the trough passage on Thursday, allowing temperatures in NorCal to rise a few degrees at the end of the week.
Extended Discussion (Saturday through Tuesday)
EPAC upper ridge remains over interior NorCal through the weekend with near to slightly above normal high temperatures.
Minor cooling early next week with increased onshore flow as Pacific frontal system moves inland and weakens.