Marine Weather and Tide Forecast for Calpella, CA

DISCUSSION
Nighttime satellite imagery reveals a blanket of stratus over the ocean waters and protruding into the coast and breaching inland. Kneeland Airport is beginning to get coverage and this implies a deep marine layer, and a glance at the Mckinleyville profiler confirms the deepened state to be upwards of 2500 feet. This occurrence can be attributed to falling pressure heights in advance of a weak shortwave and associated dry frontal boundary. This depth will keep chances lower for fog visibility, but the diurnal breakdown to clearing will likely be hindered. HRRR modeled wind streamlines handle wind eddies fairly well, and depict one over Humboldt Bay through late morning and southerly return flow along the coast south of Cape Mendocino today. These work to feed the stratus back into the coast when the northerly winds would otherwise peel it away sooner. The northerly winds are expected to eventually win out going into the afternoon for Humboldt Bay, but areas south of Cape Mendocino may see longer lasting coastal cloudcover.

High-resolution models generate a cumulus field this afternoon as the front passes near peak heating. There will be a brief wave of fleeting mid level moisture, thus a lone shower or two tied to the high terrain of Trinity County cannot be ruled out this afternoon.

Northerly winds will increase to breezy levels this afternoon behind the front and as a thermal trough begins developing. The strongest wind gusts will be experienced across Del Norte county coastal headlands. The thermal trough further strengthens Sunday when a weak shortwave trough clips N CA. There will be a brief pulse of MUCAPE over portions of eastern Trinity County as the shortwave passes, and models try to develop very isolated convective activity in neighboring Shasta County, and if anything develops that is where is will stay due to very limited low to mid level moisture over Trinity. Winds behind the trough will maximize Sunday afternoon and wind gusts of 25 to 35 mph will be likely along the exposed coastal headlands. Wind gusts of 45 mph are possible out over the Del Norte Coastal headlands (45% chance from NBM).

The gusty northerly pattern will persist through much of next week before the pattern breaks down with the influence of a cold midlevel trough. Clusters and ensembles are in firm agreement on general influence of this trough, but differ greatly in the depth and position of the trough as it moves into N CA or farther north of the PAC NW. As a result, there are a lot of questions as to how much precipitation would make it to our forecast area late next week or through next weekend. Initially, there may be some convective activity with increasing instability and moisture from a front on Thursday.

The ensemble members have good agreement on at least some very light rainfall, and NBM has growing chances for over 0.25 inches of rainfall in a 24 hour period (33-45%) over next weekend. With snow levels forecast to be near 5000 feet, there may be some late season light mountain snowfall. A resulting cooldown will also have to watched for frost development with the growing season underway.
Currently NBM has moderate probabilities for temperatures lower than 36 for the valleys of interior Mendocino County on next Sunday morning (4/27). /JJW



AVIATION
Southerly wind near shore combined with a stronger and lower marine inversion have helped promote an enhanced marine layer along shore overnight with IFR ceilings at all coastal terminals.
That said, the shallower marine layer has struggled to extend inland, allowing for VFR conditions across most inland valleys. \

Building northerly wind will most likely help scour out marine stratus in more exposed areas of the coast (like KCEC) by late morning. More protected areas such as near Humboldt Bay will see ceilings linger longer, but most models (80%) show conditions clearing to VFR by mid afternoon. Gusty north wind and weakening high pressure will both lower the probability of a marine layer reforming Saturday night, but IFR ceilings will remain possible (30% chance) for at least some of the night. /JHW



MARINE
After a couple day of calm, fresh northerly breezes have gradually begun to build in the outer water with gusts over 25 kts overnight. A passing upper level shortwave will help further enhance winds through the day today. Gusts will reach over 30 kts in the outer waters with gusts up to 25 kts pushing into the inner waters in the afternoon. Steep short period seas will gradually build alongside the wind.

Winds will only continue to increase on Sunday with solid gale force conditions throughout the outer waters with gusts in excess of 35 kts. Winds in the inner waters will ebb and flow with strongest winds pushing near shore in the afternoon. Regardless, steep short period seas up to 12 feet will fill in all across the waters. ELevated conditions will be long lived with gale force gusts and steep seas most likely to persist through at least Tuesday. /JHW



EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 9 AM PDT Tuesday for PZZ450.

Small Craft Advisory from 3 PM this afternoon to 9 AM PDT Tuesday for PZZ455.

Small Craft Advisory until 9 AM PDT this morning for PZZ470.

Gale Warning from 9 AM this morning to 9 AM PDT Tuesday for PZZ470.

Small Craft Advisory until 3 AM PDT Sunday for PZZ475.

Gale Warning from 3 AM Sunday to 9 AM PDT Tuesday for PZZ475.