textproduct: Eureka

SYNOPSIS

Temperatures will slowly warm for the interior into the weekend. A shallowing marine layer may allow for some break in gloomy clouds close to the coast into the weekend.

KEY MESSAGES

-High pressure building into the weekend will warm interior temperatures. High temperatures will peak Sunday and Monday with minor to moderate heat risk for interior valleys in Mendocino, Lake, and Trinity Counties.

-Gloomy coastal skies more likely to scatter and clear alongshore in the afternoons this weekend with some enhanced afternoon northerlies around Sunday.

-Cooler temperatures and slight thunderstorm potential late next week.

DISCUSSION

Gentle zonal flow has persisted over the area again today. Very weak ridging will arch over the area into the weekend. This will bring slightly warmer and drier conditions to the interior. Interior highs will be slightly above normal in the mid 80s by Saturday. Building heat will help shallow the marine layer along the coast. This will both increase the potential for night time fog but also increase the potential for some coastal blue skies in the afternoon. Friday appears to be the best chance to see blue on the coast with a 60% chance of skies at least scattering out in the afternoon. Stratus looks to slightly resurge on Saturday. North wind will increase along shore Saturday afternoon but especially Sunday. Despite a stronger marine inversion, the wind may help mix out some clouds on Sunday.

High pressure will continue to build Sunday and into early next week. High temperatures will most likely peak around Next Monday. Interior highs will most likely reach the low to mid 90s. Solidly above average temperatures will promote generally minor to moderate Heat Risk with the greatest risk in Lake COunty due to warm conditions continuing overnight. A very shallow marine layer along shore will likely make for more scattered skies in the afternoon. Should skies clear enough, coastal temperatures could reach near 60.

Most model ensemble members show a cutoff low forming up along shore mid to late next week. This low will help slightly weaken high pressure and drop interior temperatures. This low could bring a threat of thunderstorms, but most models show it staying too dry and too far offshore to bring much risk. Most thunderstorm potential late next week is now more than 10% at the moment in most models. /JHW

AVIATION

Stratus has been eroding back to the coast and lifting with the daytime heating, although stratus near-coastal locations are expected to persist with the light sea breeze. Expect mainly MVFR ceilings for the coastal terminals, while VFR for interior NW California. This evening into Friday, a deeper marine layer will develop as a frontal system will approaches from offshore. Expect IFR to MVFR ceiling for the coastal terminals. Otherwise, the frontal system will destabilize the marine layer and conditions will become variable at the coastal terminals overnight. This will favor some coastal drizzle late tonight through mid Friday morning. Stratus will push inland and reach UKI during early Friday morning to bring it MVFR ceilings through mid Friday morning, then prevailing VFR conditions. Expect MVFR to VFR conditions at the coastal terminal Friday afternoon in the wake of the front. Breezy northerly winds with occasional gusty winds from 15 to 25 kts are expected to develop Friday afternoon through Friday evening at all forecast terminals./ZVS

MARINE

No significant changes from the previous forecast. Gentle to moderate northerly breezes continue through today across the waters. Low NW waves around 3 and 5 feet at 8 and 12 seconds respectively. The short period wind driven waves are also expected to start to increase, especially south of Cape Mendocino with the moderate breezes.

Tonight and Friday, a weak frontal boundary approaching the area will diminish the winds north of Cape Mendocino. Farther south northerly winds starts to increase to fresh to strong breezes by Friday afternoon. Saturday these stronger winds are expected to begin to expand farther north with 15 to 20 kt across much of the area north of Cape Mendocino. This is expected to build the short period wind driven waves to around 4 to 7 feet. Stronger winds are expected on Sunday with near gale to gale force gusts possible by Sunday afternoon. Winds are anticipated to gradually ease early next week; however, steep seas will prevail across the coastal waters. MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 AM Friday to 11 PM PDT Sunday for PZZ455.

Small Craft Advisory from 3 AM Friday to 11 PM PDT Sunday for PZZ475.