Hot temperatures continue into the weekend. Monsoon moisture will gradually wane over the region, but a shower and thunderstorm threat will continue today over portions of Shasta, Tehama and Plumas Counties.
Discussion
Satellite/radar shows the main area of clouds and showers has pushed up to the north and east of the forecast area as the weak low slowly drifts northward near the coast. Radar still shows some light showers over Shasta and Tehama Counties with an isolated thunderstorm currently between Redding and Red Bluff.
Temperatures remain very mild across the northern Sacramento Valley where readings are currently in the 80s. Further south, skies have cleared out and the Delta Breeze has picked up a bit. Current temperatures in the Delta, southern Sacramento Valley and northern San Joaquin Valley range from the mid 60s to mid 70s, around 5 degrees cooler compared to 24 hours ago over much of the area.
The shower and thunderstorm threat today will be limited to the northern portion of the forecast area (Shasta, Tehama and Plumas Counties) as the low moves north taking the axis of deeper moisture/instability with it.
Temperatures will remain hot across the region today, though clouds may provide a bit of relief up north. Increased sunshine will likely offset any Delta influence further south.
Ridging returns Friday and Saturday behind the departing low continuing hot weather. The Delta Breeze will likely wane for a few days as the marine layer is suppressed. It’s looking like more substantial cooling will now be pushed back until Sunday when the next upstream trough approaches initiating a return of onshore flow.
Extended Discussion (Monday through Thursday)
Ensemble guidance is in decent agreement that on Monday high pressure will be just south of the area with a shortwave trough just off the coast of the PacNW. This wave moves inland and stalls out over the northern PacNW bringing more of a ridging influence to NorCal early next week. This may allow for a slight warming trend through mid-next week, although temperatures at this time only look to be 5 or so degrees warmer than normal for mid to late August.