textproduct: Eureka

SYNOPSIS

High pressure is forecast to remain over NW California through the weekend resulting in dry weather and generally above normal daytime temperatures. Overnight and morning temperatures will remain chilly with night and morning fog in the river valleys.

DISCUSSION

An upper level ridge has situated itself over the West Coast leading to large scale subsidence and adiabatic warming. Anomalous interior warmth with temperatures much above climatological norms will continue under the strong ridge. With clear skies and exceptional longwave cooling, it will continue to remain cold in the river valleys each night and morning, especially in northern Humboldt, Trinity and northern Mendo through the end of this week. The ridge aloft is not forecast to breakdown anytime soon and will continue to provide dry and stable weather conditions for NW California through the weekend.

The anomalous interior January warmth is contributing to a strong inverted trough and strengthening northeasterly winds, especially over the ridges. The most focused area of stronger northeasterly winds will be over the ridges Del Norte and Lake counties. This setup is also favorable for warmer coastal temperatures.

The offshore flow is greatly reducing the chances for coastal stratus and fog. HREF does have stratus creeping up from the south this evening, but it does not appear to have the density or optical depth that would hinder visibility beyond a few miles according to the model. Chances for the ridge to weaken or breakdown do not increase until mid next week. Probabilities for meaningful rainfall over 0.1 inch do not increase until late next week and next weekend. After another prolonged stretch of dry weather, wet weather will likely return for the latter part of January for NW CA.

AVIATION

The stratus remains off the Mendocino coast this morning. Any vis/cig reductions at KACV and KCEC look like they will be locally generated this morning. Confidence is low on whether this will form and if it does it will likely be intermittent. The offshore flow looks to keep stratus away through most of the daylight hours on Friday. Some of the models show stratus making its way onshore Friday late in the afternoon, but some hold it off the coast through early Saturday. Inland the northern valleys that have been seeing fog will likely see it this morning. KUKI will likely remain clear again as well. Winds will generally be light, aside from the easterly winds over the higher terrain. MKK

MARINE

Northerly winds have diminished and the locally wind driven waves along with them. Light winds are expected through Sunday morning. Waves have dropped to 5 to 7 feet and these are expected to continue dropping through Sunday morning.

Sunday afternoon or Sunday night northerly winds winds are expected to return and increase to 15 to 20 kt on Monday. There are still some differences in the models on how strong these will get, but most models keep them below 20 kt. Monday night and Tuesday the GFS wave model is showing a long period wave moving in and building to around 5 feet. The northerly winds are expected to diminish again on Tuesday. MKK

EKA WATCHES/WARNINGS/ADVISORIES

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