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 shallow 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 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. The ridge aloft 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.

Stratus development this afternoon is being aided by a southwesterly push. Meager stratus development over the past few evenings has been hindered by offshore flow. The trend in wind bearing aloft may be why the signaling is strong for cloud cover by the HREF although surface winds overnight may return to easterly. The resilient ridge remains over the PACNW, and will continue its regime of subsidence, helping to scatter out cloud cover over the CWA by the afternoon on Sunday. Chances for the ridge to weaken or breakdown do not increase until the middle of this coming 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...(18Z TAFs)

Stratus has returned to the coastal terminals bringing periodic IFR to LIFR ceilings. More consistent IFR to LIFR conditions are likely this evening and overnight for the coastal terminals. Interior valleys that have seen fog will likely see fog again tonight. UKI is forecast to remain VFR for the next 24 hours. JB

MARINE

Mild conditions continue with light winds under 10 kts and combined seas of 2-4 ft being observed. Northerlies increase somewhat Sunday, especially around Cape Mendocino and the southern outer waters. Isolated gusts above 20 kts in the immediate lee of Cape Mendocino with steep seas of 4-6 ft by Sunday evening. Winds ease again by Monday evening and remain light through at least Wednesday. Seas will be characterized by smaller mid and long period west swells, the largest of which builds Monday night into Tuesday at about 5 to 6 ft. JB

EKA WATCHES/WARNINGS/ADVISORIES

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