textproduct: Eureka

SYNOPSIS

Coastal areas will experience mostly cloudy skies and bouts of drizzle through this morning, primarily for Del Norte and northern Humboldt. Otherwise, dry and seasonably cool weather is forecast for the next 7 days. A highly energetic long period west swell will bring an increased risk for hazardous beach conditions Monday through Tuesday next week.

..EXTENDED DISCUSSION...(Tuesday through Friday)

Above normal 500mb heights will most likely (80% chance) keep much of Northwest California in a long stretch of dry weather all next week. However, a third shortwave trough may (18% chance) generate fleeting showers for Del Norte and mountains of Trinity on Tuesday. This second insider slider trough will carve out a larger scale trough that will promote blustery N and NE winds around mid week. With lower dew points, calm winds in the valleys, clear skies and long nights, the threat for frost or freezing temperatures will once again crop up. A killing freeze has already occurred multiple times in Trinity, northern interior Mendocino and northern Lake Counties. We have suspended issuing frost and freeze products for these areas until spring. Cold weather products for wind chill may be necessary if an unseasonably cold air mass settles over the area around mid next week. There are subtle signs of omega block break down or a westward shift in the longwave the following weekend of Dec 6-7 and consequential precip will be possible. /DUG

AVIATION

A weak passing cold front generated periods of light, shallow rain along the coast through the evening hours. Further rain is unlikely through the night, but lingering moisture has created IFR fog in some locations along the coast, especially round Humboldt Bay. IFR visibilities will gradually decrease into the morning, with most models showing clearing to MVFR (90% chance) quickly by sunrise. There is model disagreement during the day. Most (70%) showing ceilings scattering to VFR but a minority show some ceilings persisting through the day. Similar disagreement is evident Friday evening as well with a solid 30% of models showing a shallow IFr marine layers but the rest staying more clear along the coast. Otherwise, widespread valley fog will most likely continue to effect the interior during the overnight and morning hours into the weekend. /JHW

MARINE

Weak northerly winds have quickly built throughout the waters behind a passing cold front. The sea state is currently controlled by a mid period westerly swell around 10 feet, leading to moderately steep seas. This swell will quickly decay through the day Friday with mostly calm conditions headed into early Saturday.

Another mid period westerly swell will begin to build Saturday night into Sunday, again bringing mostly mild seas up to around 8 feet. Northerly winds will increase in the outer waters through the day Sunday, especially south of Cape Mendocino, with some gusts near 30 kts. Winds and steep short period seas, however, will most likely remain far from shore with much calmer conditions in the inner waters.

Similar northerly winds will continue in the outer waters early next week. A long period westerly swell up to 12 feet will begin to impact the waters Monday into Tuesday. Around the same time, northerly winds will most likely push closer to shore with potential (40% chance) for solid gale force conditions around midweek. /JHW

BEACH HAZARDS

A series of mid period westerly swells will continue to impact the waters through the weekend. The next swell will build up to 8 feet at 14 seconds beginning Saturday afternoon into Sunday. With mostly calm short period seas, the forerunners of this swell especially will pose a moderate sneaker wave risk Saturday evening with unexpected and inconsistent surf on area beaches. A second sneaker wave risk is possible as longer period swell builds Monday into Tuesday, but the overall risk of this swell is more uncertain due to the potential for short period seas to push closer to shore around the same time. In any case, the swell will increase surf and make local beaches more hazardous. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 AM PST Friday for PZZ450-470.

Small Craft Advisory until 9 AM PST Friday for PZZ455-475.