textproduct: Eureka

SYNOPSIS

Slightly cooler temperatures, along with deeper coastal stratus and overall cloudiness is expected for Northwest California early this weekend. Later this weekend and into early next week, an upper ridge will build in causing hotter and drier conditions for the interior with threats for isolated thunderstorms or showers early next week.

DISCUSSION

An upper level trough is sliding eastward affecting Northwest California early this weekend while an upper level ridge over the Southwest US continues expanding westward late this weekend and early next week. Tonight through early Sunday, a troughing pattern will cause deeper coastal stratus overnight which will push further inland up river valleys. With the slight influx of moisture and cooler air from the trough, high temperatures will be slightly cooler, especially for interior areas, for the next couple of days. Some clouds associated with the trough will push through the region Saturday.

Sunday and into early/mid next week, the upper level ridge centered over the Southwestern US will aid in advecting monsoonal moisture up to Northwestern California by Sunday/Monday. This could result in isolated thunderstorms over the Yolla Bollys and Trinity Alps. Chances are still less than 10%, but this pattern is still worth monitoring due to potential fire weather concerns. Early to mid next week, the interior will warm up and dry out with the potential for moderate HeatRisk for communities in Lake and northeastern Trinity counties.

AVIATION

An approaching troughing pattern has aided in mixing out coastal stratus for the afternoon for most coastal terminals. VFR conditions will continue into this evening before a deeper layer of coastal stratus develops and envelops the coast again in the overnight hours. Due to the deepening of the stratus layer, MVFR/IFR ceilings could infiltrate further inland up river valleys. VFR conditions are anticipated for most interior terminals throughout the TAF period.

MARINE

The surface pressure gradient continues to weaken causing winds and seas to diminish. The southern marine zones will still have small craft conditions into this evening. Calmer marine conditions are anticipated before northerly winds increase again late weekend/early next week causing more concerns for small craft advisory criteria.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 10 PM PDT this evening for PZZ455-475.