Above average temperatures and smoke to start September

September 1, 2020 – Smoke and haze from wildfires will continue to impact air quality and temperatures for the next several days. Dry weather and above average temperatures expected through the week. Record heat possible Labor Day weekend.

Discussion

Skies are clear early this morning except for areas of smoke and haze from the wildfires burning across the region. North to northeast surface pressure gradients continue across much of the area and northerly gusts in the teens and 20s mph are pretty common across the north and eastern portions of the CWA.

RH’s in the 20s and 30s percent are also common in the foothill and mountain thermal belts, and satellite imagery indicates more active burning burning occurring on some of the region’s wildfires, particularly the August Complex/Elkhorn Fire.

On the other hand, IR difference imagery shows extensive stratus along the coast and a robust Delta Breeze continues at Travis AFB. Profiler data indicate the depth of the marine layer is around 1500 ft.

High pressure from the eastern Pacific continues to build across NorCal today in the wake of yesterday’s short-wave. Breezy north winds will spread south through most of the Sacramento Valley this morning before subsiding this afternoon. Locally breezy northeast to east winds in the foothills and west slopes of the northern Sierra will peak early this morning before subsiding by midday. Hi-res smoke models are indicating more of the Sacramento Valley will clear from the smoke today, but probably not completely out of the Sacramento region.

Triple digit heat continues across the northern Sacramento Valley while the Delta Breeze will continue to moderate temperatures further to the south. The short-term peak in the heat is expected today as the north valley clears out and allows maximum insolation.

Redding and Red Bluff expected to approach 110 today, but then increasing subsidence inversion expected to trap more smoke for the remainder of the work week keeping high temps around the century mark. Further south, highs in the Sacramento region are forecast to inch upward toward the end of the week as the Delta Breeze slackens.

Extended Discussion (Saturday through Tuesday)

600 DM upper high over the Great Basin Sunday expands northwestward over NorCal through early next week.

This will result in a warming trend with record breaking heat possible Sun into Tue, dependent on smoke amounts, as 850 mb temps rise into the lower 30s deg C. Dry weather expected through the extended forecast period