


Area Forecast Discussion
Issued by NWS Eureka, CA
Issued by NWS Eureka, CA
848 FXUS66 KEKA 172105 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 205 PM PDT Fri Oct 17 2025 .SYNOPSIS...The warmer and drier pattern continues through Saturday. There is a moderate risk for sneaker waves along the coast starting this evening into Saturday. Light coastal rain or drizzle possible Sunday. Larger storm systems possible starting mid to late next week. && .DISCUSSION...High pressure is continuing to gradually build over the area. This will allow for slight warming and drying to continue during the day with the warmest interior valleys reaching near 80. That said, dewpoints have stubbornly remained near 40, largely preventing overnight frost despite the increasingly long nights and clear skies. High pressure will allow promote a diurnal, coastal marine layer to at least briefly form tonight into Saturday. A weak upper level trough quickly move across the area on Sunday. This will pool in cooler and more moist air alongside midlevel clouds. Overall moisture advection will be weak, however, most likely supporting only very light rain right along the immediate coast. Most likely rain amounts have trended further downward and are currently a few hundredths of an inch in Del Norte County. Looking south closer to Humboldt Bay, less than 10% of models show any rain. Weak high pressure and slight warming will most likely quickly reassert itself early next week, though low pressure passing to the southeast will limit the amount of warming, but there is a 50% chance of any highs over 80 in the warmest valleys. There is increasing confidence in long range forecasts that a significant rain event will impact the area late next week. Though high uncertainty remains, NBM already places a 95% chance of wetting rain all the way along the North Coast. There is an 80% chance of 3 day rainfall over 3 inches over Del Norte and the interior mountains, with 30-50% chances elsewhere. There is over a 50% chance of 3 day rainfall over 5 inches in Del Norte and the King Range. Such an event would likely be accompanied by strong south wind and rainfall amounts capable of moderate flood impacts. Heavy mountain snow is possible too, but there is more variability on how cold these systems will be. /JHW&JB && .AVIATION...Shallow stratus struggled to clear out of ACV this afternoon, when otherwise full VFR conditions took hold earlier over N CA. A highly localized eddy and shallow inversion is the culprit for the lingering stratus around Humboldt Bay. Full clearing is underway as the eddy breaks down. Northerly winds increase through this afternoon, mainly around Del Norte and CEC where 20kt gusts are forecast at the terminal. Winds will be lighter at most remaining terminals. The widespread VFR conditions will not last tonight. The marine layer currently observed 60nm over west over the ocean is forecast to push eastward into the coast this evening. Soundings show strong indications the inversion will remain shallow, with even shallower levels by early Saturday morning. Areas of dense fog with VIS 1/4SM or less will be possible with this setup given what was observed today at ACV and Mckinleyville profiler. Models continue to poorly model stratus coverage towards CEC. Mesoscale to microscale features around coastal wind eddies will likely steer the shallow stratus and fog northward. The eddy will develop around 5Z Saturday, and this is when the transport is expected northward. ACV: Probabilities for IFR at ACV increase after 3Z Saturday (50%). Chances for LIFR become significant after 7Z (45 to 55%). Chances for fog are lower (30-40%), but the setup and observations point to fog. CEC: Probabilities are low, but the setup favors stratus and fog transport into the terminal after 5Z Saturday. JJW && .MARINE...Northerly winds remained strengthened across the waters. Winds up to 25 kts persisting across the outer waters and around Cape Mendocino will shift closer to the coast this afternoon, mainly around Point St George and Cape Mendocino. Northerly winds will generally ease Saturday into Sunday morning before increasing again Sunday afternoon. Gale strength gusts are forecast around and south of Cape Mendocino Sunday afternoon through Sunday night. Northerly winds will remain somewhat strengthened into mid next week. The northerly wind pattern breaks down thereafter as a strong trough takes aim at the vicinity of N CA. Strong southerly winds are possible Thursday or Friday if this system take a more southerly track. Chances for at least sustained gale strength southerlies and large surf continue to increase through the weekend with modeled potent NE PAC cyclones. A long period west northwest swell will begin trickling in late this afternoon with 20 second period forerunners. This swell will continue building through Saturday afternoon, peaking around 10 ft at 16 seconds. A second larger swell move in late Sunday through Monday, and Breakers may reach 20 feet through that period. Additional large swells are then likely through next week with an active Pacific storm track. JJW && .BEACH HAZARDS...A Beach Hazard Statement is in effect from 6 PM this evening through Saturday evening. A long period westerly swell will arrive this evening at 2 to 3 feet at 20 seconds, and peak to 8 to 10 feet at 16 seconds Saturday afternoon. This high energy swell has the potential to bring moderate risk of sneaker waves, especially late afternoon/ early evening on Saturday. Shorter period NW swell of 5-8 ft at 7-9 seconds may initially mitigate the risk during the morning and afternoon hours on Saturday. Sneaker waves are a unique hazard, with many minutes between waves. Pay attention and stay above the high water line and any wet sand to stay safe. If the ground is wet, waves have surged there recently. Stay safe and never turn your back on the ocean! A potentially larger swell is then forecast to move in late Sunday through Monday./ZVS && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Beach Hazards Statement from 6 PM PDT this evening through Saturday evening for CAZ101-103-104-109. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until noon PDT Saturday for PZZ450-455. Small Craft Advisory until 11 PM PDT Saturday for PZZ470- 475. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png