textproduct: Eureka

SYNOPSIS

Midlevel clouds and moisture will continue to build overnight with light drizzle near the coast Monday morning. Conditions will clear again Tuesday with light rain later in the week.

DISCUSSION

Winds turning onshore today have pulled moist but cool are all across NW California as evidenced by building midlevel clouds and robust interior valley fog.

Over the next 24 hours, a weak trough passing to the north may help lift moisture, brining light drizzle along the coast and in some near coastal valleys. No precipitation (or even much cloud cover) will be seen in Mendocino and Lake Counties, with drizzle focused further north. There is little chance of any wetting rain at this point with even Crescent City having only about a 10% chance. Clearer skies will bring another chance (50% or so) of frost for interior Valleys early Tuesday, but valley fog will continue to make any frost patchy at best.

Ensembles have come into better agreement concerning a potential system later in the week and now generally show the bulk of the system staying further north of the area and weaker than early runs suggested. Most deterministic models now have only a week cold front crossing the area around Thursday or Friday. While such a front would likely pull moisture and light drizzle onshore, ensemble spread now shows only a 20 to 40% chance of light wetting rain along the North Coast with less than a 10% chance of 0.5 inches of rain anywhere. A moist and drizzly pattern will likely continue into the weekend, but potential for meaningful wind or precipitation remains low. Long range outlooks from the CPC show warmer and drier than normal conditions are most likely to persist through the first week of December. /JHW

AVIATION...(18Z TAFs)

A frontal boundary will usher in cloud cover and light rain by 02-03z at KCEC. Light precip will start at KACV a few hours later, likely around 08-09z. The model blend has cloud cover filling in by the early evening. Ceilings are ~50% probable to drop below 3000ft at KACV before midnight and ~65% likely at KCEC for a similar time frame. Ceilings could even drop lower as some guidance suggest, which could bring IFR/LIFR conditions into the early morning hours Monday at KACV. KUKI could also see a brief spell of low ceilings and low visibility by 10-12z. /EYS

MARINE

The passage of a frontal boundary has shifted winds to a southerly bearing in the northern waters and northerly winds being reported by buoy 46014 in the southern waters. As of 22z this still holds true and is likely due to the stalled nature of the front. Models show the front drifting slowly to the south and offshore overnight into Monday morning and eventually meandering inland, resulting in northerly winds prevailing all area waters by 12-14z. Northerlies will fill in at a moderate to fresh breeze sustained by the late morning after a few hours of mild conditions. A small craft advisory is likely due to cover the conditions in the outer waters initially and possibly the inner waters by Monday evening. The highest velocities will be south of Cape Mendocino, with 23-28kt gusts. Wave heights around 10ft with the westerly swell easing in period from 16-17 seconds to around 12-13 by Tuesday evening.

Tuesday and Wednesday are generally expected to see fairly light winds. Wednesday afternoon these are expected to start becoming southerly again as a frontal boundary approaches the area. There are still some discrepancies in the models on how strong these winds are expected to get on Wednesday night and early Thursday, but generally they are expected to peak around 20 kt in the northern outer waters with lighter winds farther south. Friday stronger northerly winds are expected to return and models are in fairly good agreement on this. Over the weekend the models start to diverge with some bringing in another weak weather system and others bringing stronger northerlies.

The swell is expected to continue to diminish Tuesday and Wednesday with swell heights only around 4 to 6 feet at 10 seconds. The wind driven waves are expected to diminish Tuesday night setting up a very calm day on the water for Wednesday. Total wave heights look to be around 4 feet with a dominant period of 12 seconds. The next swell is expected to build in Thursday morning. /MKK /EYS

BEACH HAZARDS

The long-period WNW swells continue to move through the waters today. Periods are around 15 seconds with intervals of longer period swell being observed at the buoys around 17-18 seconds, enhancing the threat of sneaker waves as they run up the coastline. This type of set behavior contrasts with the predictable prevailing wave action which can catch beachgoers off guard through the rest of the day and into the early evening. Breaking wave heights may reach 17-19 ft. Be cautious visiting beaches and jetties and remember to never turn your back to the ocean! /EYS /MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... Beach Hazards Statement until 10 PM PST this evening for CAZ101-103-104-109.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PST Monday for PZZ450-455- 470-475.