August 13, 2018 – Not as hot through mid-week. Highs trend upwards late this week reaching around 5-10 degrees above average by the weekend. Smoke impacts from wildfires may increase again this week.
Mainly clear skies across the region early this morning. Current temperatures are slightly cooler across most of the area compared to 24 hours ago and generally range from the mid 40s to lower 50s in the colder mountain valleys, to the upper 50s to lower 70s across the Central Valley. Little change expected across interior NorCal through mid-week as seasonably hot weather continues with the region between a weak trough to our northwest and high pressure to the southeast. The marine layer remains around 1000-1500 ft deep which will continue to provide local cooling for the Delta and portions of the southern Sacramento Valley courtesy of the Delta Breeze.
Weak cutoff low off SoCal looks to be shunted south, so subtropical moisture advection from this feature looks very minimal. However, southeasterly flow around the Southwest high will advect some monsoon moisture northward mainly on Tuesday, and if the forecast short-wave riding up the Sierra materializes, perhaps providing a better chance of northern Sierra deep convection.
Extended discussion (Friday through Monday)
Upper ridging progged to strengthen Friday into Saturday with minor warming, then weaken Sunday into Monday with slight cooling. High temperatures however remain above normal through the extended forecast period with dry weather.