Marine Weather and Tide Forecast for Redwood Valley, CA

DISCUSSION
Visible satellite imagery showed stratus and fog lingering near the coastline this afternoon. The fog and low clouds were most extensive south of Cape Mendocino with web cameras showing a much more subdued and smashed down marine layer compared to yesterday.
Adiabatic warming will most likely keep the layer compressed and shallow tonight with less inland intrusion. A sheared-out 500mb trough and surface frontal boundary will likely bring a new push of shallow moisture and low clouds to the North Coast late tonight into Saturday morning. With northerlies increasing offshore and a shallow influx of marine air a few spats of drizzle will be possible.

Northerly winds will ramp up behind the first shortwave trough on Saturday with the strongest wind gusts mostly across Del Norte county coastal headlands. Additional shortwave troughs in the westerlies aloft will follow Sun-Mon and will serve to reinforce the blustery and windy coastal northerlies. Confidence northerlies will break down the persistent stratus locked-in south of Cape Mendocino and offshore the Mendocino coast remains low. Models have not been handling small scale eddies spinning up each day. Strong surface high pressure will remain nearly stationary just outside 140W and north of 40N into early next week and windy diurnal coastal northerlies are probable each day. The one exception will be the Mendocino coast where eddy circulations and stratus may persist each day.

Precipitation chances remain low to non-existent through mid next week as series of troughs in westerly flow traverse across the area. 24-hour ensemble cluster means show a potential for a somewhat wetter scenario Tue-Wed. All this may end up amounting to is a few showers over the mountains. Not really confident in any significant precipitation the next 5 days, so will stay with the NBM guidance at this point. A cooling trend of high temps and a deeper marine layer with more cloud cover should commence around mid week and may continue into the latter portion of next week.

Weather could get much more active and anomalous toward the latter portion of next week and next weekend (Fri 4/25 to Sat 4/26) as a deep 500mb cold core moves toward or across the NW Cal. There are multiple possible outcomes. One extreme is a cut-off low may form well offshore or the 500mb cold core may head south leaving NW California high and dry with no rain or mountain snow. Another possible outcome is one that will feature bouts of rain, high mountain snow and perhaps isolated thunderstorms. A mix or blend of both of these is also possible. Now, latest NBM indicates a 30-50% chance for 0.25in to 0.50in of rain in 24 hours for Del Norte/Humboldt and a 10-30% chance elsewhere Thu-Sat next week.
There is even a chance for snow in the high mountains, above 5000 feet. Though amounts do not appear to be very impactful compared to winter standards. If this wetter and colder scenario pans out, it will get quite chilly in the high mountains with subfreezing low temps and near freezing high temps. DB

AVIATION
Coastal fog has been creating TEMPO periods along coastal terminals. LIFR conditions due to low level stratus consists of ceilings of VV002 and Visibilities between 1-3SM. However, minimal high clouds are keeping terminals in VFR when the fog is not present. Winds are light today, under 10kts from the north. Tonight around 0900Z , HRRR model data shows over a 70% chance of coastal fog in and around humboldt Bay and at KACV. Fog is forecasted to remain through most of tomorrow. Inland at KUKI, morning fog has burned off and clear skies are forecast through the day. LAMP data shows a 40% chance of LIFR ceilings (<500ft) returning late tonight into tomorrow morning around 09-12Z. DS

MARINE
Calmer conditions will persist today with Fresh breezes staying isolated to the far outer waters.

A passing upper level shortwave this weekend will once again push strong northerlies closer to shore. Gale force gusts up to 35 kts are most likely (~85% probability) in the outer waters with gusts up to 25 kts pushing into the inner waters each afternoon. Some HiRes guidance (CANSAC model) shows stronger winds (sustained ~30kts), yet forecast confidence on winds of this strength manifesting in the inner waters remains low. Winds build steep short period wind waves once again in excess of 12 feet. Consistent, strong north wind is most likely to continue through most of next week. /JHW/DS

EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from 9 PM this evening to 9 AM PDT Monday for PZZ450.

Small Craft Advisory from 3 PM Saturday to 9 AM PDT Monday for PZZ455.

Small Craft Advisory until 9 AM PDT Saturday for PZZ470.

Gale Warning from 9 AM Saturday to 9 AM PDT Monday for PZZ470.

Small Craft Advisory until 3 AM PDT Sunday for PZZ475.

Gale Watch from late Saturday night through Monday morning for PZZ475.