textproduct: Eureka

SYNOPSIS

Cold temperatures overnight are to be expected inland this morning and Saturday morning. Conditions will quickly warm and dry into the weekend with light drizzle along the coast early next week.

DISCUSSION

Offshore flow continuing overnight combined with drier air may allow for patchy frost formation in interior valleys of Trinity and NE Mendocino counties. That said, the addition of moisture to the environment from rain is already showing to enable the formation of fog, which reduces the likelihood of frost formation. Closer to the coast, unstable conditions will make any marine layer formation unlikely, leading to clear skies with the exception of radiation fog forming in the coldest lower elevations spots.

Cold air will quickly be pulled east of the area with high pressure and offshore flow generating quick warming and drying today into the weekend. By Saturday, interior highs will generally return to the mid 60s. Dry conditions may allow for continued frost concerns through Saturday morning, but the chance of proper freeze conditions remains low (less than 10% via HREF/REFS probabilities). Offshore flow Saturday will likely also help keep the coast clear but winds turning more onshore by Sunday will likely promote some coastal stratus formation.

Most ensemble members show a weak trough moving onshore well north of the area early next week. That said, most members show light rain and drizzle along the North Coast in Del Norte and Humboldt counties with a 90% chance of at least trace rain amounts in Crescent City, however an increasing probability (~15-20%) of any amounts over 0.3 inches. In the Humboldt Bay area, there is a 45% chance of no rain at all and less than 10% chance of even wetting rain (>0.01"). High pressure will then again most likely briefly build over the area by for Thanksgiving Day. /JHW&DES

AVIATION...(6Z TAFs)

Widespread low clouds are being observed in the interior valleys, but so far these have mostly avoided the major terminals. Weak offshore flow could promote some brief impacts to all the terminals at times before sunrise. Clouds will likely lift and scatter after sunrise, with VFR conditions likely through the day Friday. Winds will generally shift northerly and generally remain light. Offshore flow is likely to keep skies clear into the overnight hours Friday night. JB

MARINE

Northerly winds have started to build as high pressure begins to build. Meanwhile, a large WNW swell has filled in bringing steep waves of 15-17 ft at 15 seconds. Seas have already started to begin to ease and will continue to ease through the day. Northerly winds will peak this afternoon and evening with gusts up to 30 kts in the outer waters and 15-20 kts nearshore. Steep short period waves of 6-10 ft will accompany these winds. Winds ease into Saturday as the pressure gradient weakens. However, another large long-period NW swell of 10-12 ft is forecast to fill in Saturday, returning combined seas of 12-15 ft. Seas gradually subside going into Sunday and Monday, but northerlies are likely to return Sunday into Monday. Milder conditions are forecast to return by mid next week. JB

BEACH HAZARDS

A large W-NW swell has filled in, bringing a risk for dangerous surf through Friday morning. Breakers from 18 to 22 feet are being observed and large surf is likely to continue into Friday morning. The swell is too large for sneaker wave criteria and too low to warrant a high surf advisory, but still caution should be exercised on beaches and jetties. A longer period W-NW swell group from 8-12 ft with dominant periods near 16 seconds is forecast to build over the weekend. This swell may pose a greater risk for sneaker waves and continued erosion of beach profiles.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Frost Advisory until 10 AM PST this morning for CAZ107-108- 111.

NORTHWEST CALIFORNIA COASTAL WATERS... Hazardous Seas Warning until 9 AM PST this morning for PZZ450-455-470-475.