textproduct: Eureka

SYNOPSIS

Cloudy and misty conditions expected this morning. A warm front with light rain and drizzle passes over Del Norte and Humboldt counties today. Generally dry weather conditions is expected to prevail across NW CA this coming week, with periods of light rain/drizzle for the North Coast.

DISCUSSION

A stubborn high pressure center has been sitting off the California coast for a few weeks now. The strength of the high pressure has been keeping the storm track far to the north of NW CA for the last few weeks. This slower start to winter will continue this week with increased moisture, yet not enough forcing will be present to create meaningful precipitation amounts as most of the vertical vorticity of a frontal system to the north will be focused in Oregon, only briefly and periodically clipping NW CA. The increased atmospheric moisture will create fog and low clouds along the coast and in the inland valleys. Increased cloud coverage will keep nighttime temperatures on the warmer side for the season.

A passing warm front will bring light rain and/or drizzle across mostly Del Norte and Humboldt counties later today. Total storm precipitation amounts will be minimal and mostly north of Humboldt Bay and West of the Klamath River. REFS probabilities shows only a 20-30% chance of wetting rain in Del Norte and a 0-15% chance of wetting rain in northern Humboldt Co. Elsewhere, drier weather conditions will prevail with morning valley fog, mist and low clouds.

High pressure slowly builds back over the area next week in the wake of the frontal passages. The general consensus between the ensemble and operational models is dry weather conditions across much of Northwest California, with intermittent light rain/drizzle in Del Norte County through Thursday at the earliest. The dry weather allows for a gradual warming trend through the week, with interior high temperatures warming up to mid 60s to mid 70s late in the week peaking on Thursday.

Some ensembles are indicating a pattern change by mid December but there is a large amount of uncertainty as it is too far out in time to have any true meaning for the forecasts. -ZVS/DES

AVIATION...(06Z TAFS)

Periods of LIFR to IFR stratus will continue into early Sunday for coastal areas ahead of an approaching front. Light rain is possible over Humboldt and Del Norte starting early Sunday morning around 12Z. Some interior valleys may see stratus and fog again tonight, but confidence at UKI is lower. JB

MARINE

Northerly winds and seas have eased as front moves in north of our area. Generally light winds are forecast this weekend, with south winds forecast north of Cape Mendocino and west-northwest winds forecast south of the Cape. A mid period northwest swell will continue and peak at around 7-9 ft at 12 seconds. Wave heights peak early Sunday morning. Combined seas could briefly reach or exceed 10 ft, especially if the swell fills in higher than forecast. Seas subside Sunday and Monday as this swell decays. Light winds continue into early next week, but seas will remain elevated as a series of mid-period northwest swells fill in from systems to the north. JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None.