128 FXUS66 KEKA 242128 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 228 PM PDT Fri May 24 2019 .SYNOPSIS...An isolated shower or thunderstorm will be possible over the Yolla Bolly Mountains this afternoon and evening. Meanwhile, low clouds and patchy drizzle will likely redevelop over Humboldt Bay during part of tonight. A more substantial chance of showers is expected to develop over northwestern California during Saturday evening. Thereafter, daily afternoon shower and thunderstorm potential will exist over the interior mountains Sunday through Friday. && .DISCUSSION...Daytime heating is aiding in boundary layer destabilization over the Yolla Bolly Mountains this afternoon, which is resulting in isolated shower development. That activity will dissipate this evening with the loss of daytime heating. The other short-term concern will be the redevelopment of stratus over Humboldt Bay tonight. Model forecast soundings indicate that a sufficiently deep saturated layer will be present for patchy drizzle as well. However, WV imagery shows an upper low moving south across WA and OR, and that feature is forecast to usher in a slightly drier and less stable boundary layer airmass during the next 12 hours, which may aid in clearing stratus away from the coast late tonight into Saturday morning. The previously mentioned upper low is forecast to move south across NRN CA during Saturday night. Multi-model guidance indicates widespread light shower activity will be probable with the low across the entire region Saturday evening and night. Showers are then forecast to clear during Sunday as the upper low moves south of the area. However, sufficient destabilization is forecast to occur over the Trinity and Yolla Bolly Mountains Sunday afternoon for showers and thunderstorms...that pattern is forecast to repeat every afternoon from Monday through Friday. JMG && .AVIATION...Marine stratus with ceilings near 1000 feet, as well as patchy drizzle, are forecast to redevelop this evening in the vicinity of Humboldt Bay. Farther north, model forecast soundings show stratus briefly redeveloping at KCEC during Friday evening. However, a slightly drier and less stable airmass is forecast to spread south across the region late tonight...which may scatter out low cloudiness at KCEC, and perhaps even KACV. Over interior Mendocino County, a period of low clouds/MVFR ceilings will be possible over the Russian River Valley toward 06Z/Saturday. JMG && .MARINE...A strong area of surface high pressure persists over the NERN PAC Friday afternoon. That feature is forecast to shift southward over the weekend, which will eventually lead to weakening north winds and seas Sunday and Monday. In the meantime, gale force northerlies will develop over the southern outer waters tonight and will be accompanied by steep seas from 10 to 13 feet. Elsewhere, solid small craft conditions are probable over the northern outer and northern/southern inner waters through Saturday night. JMG && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 5 PM this afternoon to 11 AM PDT Sunday for PZZ450-455. Small Craft Advisory until 5 PM PDT Sunday for PZZ470. Small Craft Advisory until 2 AM PDT Saturday for PZZ475. Gale Warning from 2 AM Saturday to 5 AM PDT Sunday for PZZ475. && $$ Visit us at http://www.weather.gov/eureka Follow us on Facebook and Twitter at: http://www.facebook.com/NWSEureka http://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: http://www.weather.gov/eureka/zonemap.png