Marine Weather and Tide Forecast for Little River, CA

DISCUSSION
An elongated upper level trough continue to dig southward along the West Coast. Coastal stratus remain blanketed the west coast this afternoon, while cumulus clouds has been developing over the interior higher terrain due to an elevating instability, especially around the Trinity Alps and Yolla Bolly.
Latest doppler radar depicts light to moderate showers developing across Trinity County. There remain a potential (15-25%) for thunderstorms late this afternoon and evening. The best chance of thunderstorms will be over Trinity County.

Tonight into Friday, the upper level trough split and becomes in a cutoff low off OR/CA coast. This will bring an increasing mid to high level moisture across the region. CAMs indicated isolated showers moving toward the north coast with the flow aloft shifting to south-southeast Friday morning. Scattered to numerous showers are expected Friday afternoon through Saturday as the cutoff low continue driving southward along the coast toward central California. Saturday's high temperatures are forecasted to be 5 to 12 degrees below normal. ECMWF Extreme Forecast Index (EFI) highlight highs in the 60th-80th percentile below normal temperatures on Saturday, especially for the interior areas in southern Humboldt, interior Mendocino and Lake County. Overnight temperatures are expected to remain in the 40s across the valleys due to lingering low level moisture.

Sunday clearing skies are expected and temperatures will start to warm back up again as a high pressure begin to builds in downstream in the wake of the trough. Inland areas are expected to see highs in the 60s. Sunday night into Monday morning is expected to be the coldest night and frost is possible in the colder valleys. High pressure continues to build in through the week with highs around 80 for the inland areas by Wednesday.

AVIATION
A deep marine layer with tops up to 3500 feet is forecast to persist tonight into Friday. MVFR ceilings are forecast to prevail, however shallow moisture aad northwesterly surface flow will likely yield periods of IFR conditions in light precip tonight into Friday morning for coastal aerodromes. Cumulus convection and possible thunderstorms are also expected over the interior this afternoon and early evening. Wrap around moisture and rain may also result in MVFR conditions (20% chance) later tonight/Friday for location outside aerodrome airspace. DB



MARINE
Wave spectrum remained heavily skewed toward shorter period bands (less 8 seconds) today. Multiple mid period wave bands were also present, centered near 14 and 11 seconds. Longer period W and SW swell groups (>15 seconds) were contributing much less to the total sea state which has been fluctuating near 5 ft. A lighter NW wind regime (5 to 15 kt) is forecast to continue for tonight and Friday with steep seas continuing on a downward trend.

A weak surface low and cold frontal system will approach the outer waters tonight and continue to weaken the pressure gradient across NW California waters. Lighter winds around 5 to 15 kt with seas 5 ft or less are forecast on Friday. In the wake of the frontal system, northerly winds will begin to increase Friday night through Saturday as high pressure builds eastward toward the outer waters. Pressure gradients tighten some by Saturday, however there are considerable differences between the models and the rate at which northerly winds increase Saturday. NBM probability for wind gusts > 25 kt increase to 60-70% on Saturday, highest in the outer waters and downwind of Cape Mendocino. Wind gusts up to 30 kts are expected by Sunday over these same areas. Our spring time northerly wind regime will return this weekend and continue into at least early next week. There is a chance for gale force gusts over 34 kts (40% chance) on Monday, mainly for the afternoon south of Cape Mendocino. The duration and coverage appears quite limited and no highlights are necessary. DB



EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
None.