507 FXUS66 KEKA 032130 AFDEKAAREA FORECAST DISCUSSION National Weather Service Eureka CA 230 PM PDT Fri Oct 3 2025
.SYNOPSIS...Dry weather and locally gusty winds are expected through early next week. Cool mornings and warmer daytime highs are expected for the interior valleys through early next week. Anomalous warmth will be possible for the North Coast on Monday.
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.DISCUSSION...Dry weather and locally gusty winds are anticipated through the weekend. Strongest northerlies this afternoon/tonight will most likely be over the coastal high terrain of SW Humboldt/NW Mendo and over portions of the Mendo coast as a low level northerly speed max develops in lee of Cape Mendo. A front will approach from the NW on Saturday and is forecast to dissipate before reaching the North coast. Gustier higher terrain northerlies are forecast to return on Saturday and prevail into Sunday as an inverted trough develops along or near the coast. Winds overall for most land sites will not be very strong, however locally strong and gusty E-NE winds are forecast to ramp up Sunday night over high terrain and ridges.
Gradual drying is expected for the interior valleys after multiple days of rain. There is a possibility for localized frost for the colder interior valleys, about 30-40% chance in Trinity County at places like Ruth and Hayfork. Chances are less for northern Mendocino and northern Lake, 10-20%. Larabee Valley near Dinsmore has the highest chance, about 60-70% chance. Fog and low clouds will most likely form across the interior valleys tonight and counteract the longwave cooling. Drying offshore flow Sunday into Monday may yield better chances for early morning frost as skies remain clearer longer. The air mass does warm up considerably over the weekend into early next week with interior valley high temperatures well above normal (lower to mid 80s Sunday and Monday). Latest indications are for stronger offshore flow and increased potential for anomalous North Coast warmth with high in the lower to mid 70s on Monday.
Greater forecast uncertainty crops up on Monday if a southerly wind reversal develops along the Mendocino Coast. This southerly wind reversal may result in coastal stratus and fog for the Mendo Coast and SW Humboldt coast. With warmer air mass and weak onshore flow. shallow marine layer stratus and fog may begin to return to the North Coast by Tue and Wed.
Not much chance for rain even into mid next week as weak front passes into the Pac NW. There are signs for more wet weather late in the week as another surface low and frontal system approaches the Northern California coast. Ensemble 500mb means and anomalies from the various global models (ECMWF ENS, GEFS and CMCE) indicate considerable variability with the time evolution, placement and depth of the 500mb cold core. Most all WPC 500mb clusters show this trough right offshore by day 5 (Thu), traversing somewhere across or nearby the West Coast days 6 to 7 (Fri-Sat). It is possible (10-20%) for another 1" of rain over 24 hours for NW California mountains by late Fri. Stay tuned as next weekend may be wet and unsettled if this trough/cold core low complex takes longer to advance across the forecast area.
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.AVIATION...(18z TAFs)...Clouds continue to dissipate for terminals around Northwest California as a front continues east. Behind the front, north to northwesterly winds along the North Coast will continue to increase this afternoon and most likely tomorrow afternoon, as well. The highest gusts for this afternoon and evening are forecast to be around Point St. George in Del Norte County and along the Mendocino Coast with models showing an 80 to 90 percent chance for gusts greater than 25 knots. While north to northwesterly winds are expected to increase along the coast from the Del Norte/Humboldt county border to Cape Mendocino, gusts are not anticipated to be as high.
Coastal stratus, along with general cloudiness, is not expected to be widespread due to general offshore flow, especially over Del Norte County. Periods of MVFR to IFR ceilings could occur along the Humboldt Coast north of Cape Mendocino this evening and into early Saturday, especially around Humboldt Bay. KUKI is expected to remain VFR through this current TAF period with general northerly winds expected to pick up this afternoon. /JLW
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.MARINE...Combined seas have dipped below 10 ft across the waters. Northerlies continue to fill back in and strengthen today with gusts peaking around 20-25 kts this afternoon in the outer waters and nearshore Mendocino. Winds nudge further upward Saturday, bringing localized gale force gusts in the waters in the lee of Cape Mendocino. Peak gusts elsewhere range from 20-30 kts.
Gale potential expands late Saturday into Sunday with NBM showing a 24 hour probability of 80 to 90% for gales in the southern waters. Chances are less certain for gale conditions for the northern outer waters. Short period seas will dominate the sea state, with steep waves of up to 7-9 ft currently forecast by the weekend. These will likely propagate into the inner waters, even as winds remain lighter. High pressure weakens by late Sunday into early next week, and winds are likely to ease. JB
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.EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 PM PDT Saturday for PZZ455.
Small Craft Advisory from 11 AM to 11 PM PDT Saturday for PZZ470.
Gale Watch from Saturday evening through Sunday morning for PZZ470.
Small Craft Advisory until 3 PM PDT Saturday for PZZ475.
Gale Watch from Saturday afternoon through Sunday morning for PZZ475.
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NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed.
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NWS EKA Office Area Forecast Discussion