Spring-like temperatures through the weekend, followed by strong winds

January 15, 2021 – Dry weather into next week with areas of late night and morning valley fog. Well above average temperatures will continue into next week. Strong winds possible early next week.

Discussion

Infrared satellite imagery reveals developing Tule Fog in the Central Valley this early Friday morning. Visibilities are already down to a quarter-mile at several airports. Consequently, a Dense Fog Advisory is in effect for the southern Sacramento Valley, the Delta, as well as the northern San Joaquin Valley through 11 AM PST Friday.

A broad upper level ridge parked about 400 miles west of Santa Barbara will promote another afternoon with temperatures well- above January normals. Most communities in the Sacramento Valley will max out in the 60s. Similar to yesterday, localized areas with lingering fog into the afternoon hours may struggle to get out of the upper 50s. For reference, normal high temperature for January 15 at Downtown Sacramento is 54 deg F and 55 deg F at Redding.

The offshore ridge is forecast to amplify over the weekend, leading to further warming across much of the Golden State. Unfortunately, this also means that dry conditions are forecast to prevail as we dive deeper into what is ordinarily the wettest time of the year.

A shortwave will ripple around the outer periphery of the upper level ridge late Sunday and into Monday, quickly diving south from the Pacific Northwest into California. A second piece of energy will drop south on Tuesday as an inside slider, reinforcing northeasterly, and potentially strong/damaging offshore flow. More on that in the extended discussion section.

Extended discussion (Tuesday through Friday)

A closed off upper level low will be set up over SoCal with a strong Pacific high begining to build into NorCal. This will bring a strong pressure gradient over the region with strong north to east winds late Sunday night into Tuesday. NAEFS shows a band of anomalous winds (30+ year return intervals) for the wind component.

Current forecast indicates wind gusts ranging from the 30 to 40 mph in the Valley and into the Delta, locally higher. There is the potential for higher wind gusts up to 70+ in favored gaps, canyons and ridgetops. Weakened or burned trees and limbs may fall in strong winds. Stay tuned for details.

Dry weather is expected for much of the extended period as we sit on the eastern edge of the Pacific high. The ridge will push west late in the week as a short wave trough digs down the coast. This may bring some light showers to the area. NBM guidance shows daytime temperatures gradually cooling down through the period, but highs could still remain above normal for mid January.