August 20, 2017
Summary: Temperatures this Sunday morning are generally running 2 to 3 degrees cooler than 24 hours ago. Marine air is surging through the Delta and is moving through Pacheco Pass where winds are currently sustained at 20 MPH. The pattern over the next 72 hours will be a bit complex. There is a low center off the south/central California coast which continues to add convection to the mid to upper layers of the atmosphere. This is triggering afternoon and evening thunderstorms over the Sierra Nevada.
The low will remain in place today, but will begin to move a bit further south Monday. This will create an interesting scenario as the counterclockwise circulation around the low will begin to pick up moisture from a slug of monsoon moisture currently moving eastward through New Mexico and western Arizona. This moisture will arrive in central California later Sunday night or early Monday. Thunderstorms will spread over the Kern County mountains and deserts with numerous cells over the Sierra Nevada. With the circulation around the low, the winds will become east to southeast, which could sustain isolated showers or thunderstorms over the valley floor Monday through Tuesday night, especially along the Sierra Nevada foothills and in Kern County.
The chance of measurable precipitation is between about 15% to 20% at any given location. This pattern will continue through Tuesday night. On Wednesday, the low will move to the south then to the east, allowing a westerly flow to begin to infiltrate central California, ending any chance of rain on the valley floor.
Clear skies will prevail Thursday and beyond as a blanket of upper level high pressure will cover the eastern Pacific Ocean and the western United States. Temperatures Thursday through Saturday will be marginally above average, generally huddling in the upper 90s to near 100 with a continuation of stable weather next weekend and next week as well.
Forecast: Mostly clear this morning. Mostly clear to occasionally partly cloudy, mainly along the east side, later this afternoon and evening. Partly cloudy Monday through Tuesday night with a slight chance of isolated showers and thunderstorms, mainly in the afternoons and evenings. Clearing Wednesday. Mostly clear skies Thursday through Sunday.
Short Term: High temperatures today through Tuesday will range in the mid to upper 90s. Overnight lows will cool into the upper 50s in the cooler locales to the mid 60s elsewhere. However, if there is significant cloud cover, lows will be in the mid 60s to the lower 70s. temperatures Wednesday through Sunday of next week will top out in the mid to upper 90s with lows generally ranging in the low to mid 60s north of Kern County and the upper 60s to mid 70s in Kern County.
Next update: Monday morning