textproduct: Eureka

SYNOPSIS

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

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 have started to increase and are now 15 percent in northern Trinty county on Tuesday. Other areas 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

With the upper mid level low encroaching on our area, although be it slight, there is an introduction of moisture and instability that could effect flight categories and weather in general as monsoonal mid level moisture arrives over the next few days. With mixing there will be a deeper marine layer and subsequently higher ceilings overnight into Saturday morning of 1200ft or so with models hinting at a few hours of LIFR at KACV and KCEC. Variable winds out of the east at times but mostly light at KUKI with prevailing VFR conditions into the morning hours. Northerly winds will build at KUKI by 18-19z, sustained under 10kts or so. /EYS

MARINE

The surface pressure gradient continues to weaken causing winds and seas to diminish overnight but expect northerlies to build by Saturday afternoon. Localized areas south of Cape Mendocino will reach gale criteria, Saturday afternoon and into Sunday early morning. 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 3 AM PDT Sunday for PZZ455-475.