Marine Weather and Tide Forecast for Philo, CA

DISCUSSION
A closed low center located just near 39N and 127W continue to track southeast toward central California through Saturday. This is promoting above normal moisture values across across Northwest California, especially along the North Coast this afternoon. Diurnal heating are promoting isolated showers are already around the Yolla Bolly. There is some shallow instability this afternoon with a cold air aloft over Trinity capable of produce moderate showers bands. For the rest of the day, showers activity are expected to increase in coverage this evening with increasing low to mid level moisture as the aforementioned low moves closer.
Expect scattered to numerous showers across the area through Saturday, with periods of moderate rain rates. Precipitation will tapper off from north to south Saturday evening as the trough eject the area, with lingering showers through Sunday morning.

Saturday's high temperatures are forecasted to be 5 to 15 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.

Breezy northwest winds will developed along the coast Saturday afternoon through Sunday as a surface high pressure begin to builds in and tighten the pressure gradient. Gusts from 25 to 35 mph are forecast for the coastal headlands and exposed ridges, with strongest winds over the more prominent exposed terrain. HRRR probabilities indicates there is a 50 to 75% chance of wind gusts greater than 30 mph for the North Coast Saturday evening, then increasing chance up to 50% across the Mendocino Coast late Saturday night.

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. Areas of valley fog are expected to develop Sunday night into Monday. High pressure continues to build in through the week with highs around 80 for the inland areas by Wednesday.

Ensemble clusters and deterministic models shows the high pressure shifting eastward on Thursday. Most of the cluster members (78%)
suggest an upper level trough approaching the area next Friday. However, there is uncertainties with the position of the low and if there will be any impacts to our area. ZVS



AVIATION
Upper level low spinning around near 39N 127W will continue to track southeastward toward central California tonight through Saturday. Multi-layered cloud cover and moist air will continue to wrap around the low center into the area tonight through Saturday, resulting in mostly MVFR conditions. Periods of IFR conditions are also expected for mostly coastal areas with a steady low level NW flow and a shallow humid layer. The occurrence of wrap around precipitation will increase the chance for IFR and MVFR conditions outside the terminal aerodrome airspace. Surface pressure gradients will begin to tighten on Saturday as the low tracks southeastward while high pressure builds toward the NW California coast. Gusty north-northwesterly winds and low level turbulence are anticipated for coastal aerodromes, especially at KCEC, in the afternoon. DB



MARINE
Wave spectrum remained heavily skewed toward shorter period bands (less than 10 seconds) today. Multiple long and mid swell groups from the SW and W were also present and contributing much less to the total sea state which has been 4 feet or less. 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.

Marine conditions are forecast to deteriorate this weekend and remain hazardous into at least early next week. On Synoptic scale, a weak and diffuse surface low over NRN California outer offshore waters (150-250NM) SW of Cape Mendo is forecast to move southeastward tonight through Saturday into central California offshore waters. Surface high pressure is forecast to build toward the Pac NW Saturday afternoon resulting in a tighter pressure gradient over NW CA coastal waters. Model derived 10 meter winds continue to show variability with the rate of increase and location of the speed max. Leaned toward the ARW and FV3 and the HRRR mean with strongest wind max over the northern waters around Pt St George during the afternoon and early evening hours. Coverage and duration of gale gusts over 34kt appears limited for a gale warning at this time. Steep northerly wind waves will build during the late afternoon and peak around 10 ft around 9 seconds. This will be borderline for a low end hazardous seas warning for primarily the outer waters or 10 to 60NM from shore into Sunday morning. Our spring time northerly wind regime featuring locally strong northerly winds around Pt St George and in the lee of Cape Mendo as well as steep northerly waves near 10 ft will most likely stick around on Sunday into early next week. DB

EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from 3 PM Saturday to 9 AM PDT Sunday for PZZ450-455-470-475.