Marine Weather and Tide Forecast for Westhaven-Moonstone, CA

SYNOPSIS
A series of upper level troughs off the west coast are expected to generally keep inland temperatures near normal.
Persistent marine clouds expected along the coast with some afternoon clearing. Late in the week, a stronger trough will bring cooler inland temperatures and even the potential for inland thunderstorms.



DISCUSSION
A very brief shortwave ridge has built over NW CA.
Offshore flow in Del Norte county will likely keep the coast clear through most of the evening. Monday, another trough approaches from the southwest. Temperatures are expected to be close to average again, yet some smoke in the northern valleys could keep temps. in the low 90s. Some high clouds are expected to move over the area in the afternoon, as a shortwave disturbance moves over the area. There will be minor instability with this feature, yet it doesn't look like there will be enough moisture for any thunderstorms. IF anything, this lift could simply help move smoke away from the valleys, which would be beneficial.

Tuesday the ridge builds back to the west and will ever so slightly increase inland temperatures above normal back to the mid to high 90s. Coastal clouds may see a few breaks in the afternoon, but are generally expected to be pretty persistent, yet again. Wednesday, the another push of energy from an upper level trough in the east Pacific starts to push the ridge to the east, however, this will not impact the area until late week.

Thursday and Friday, the aforementioned upper level trough is expected to move by the area. A couple of the model clusters are continuing to show the vorticity lining up with the afternoon heating on Friday. This alignment increase the likelihood of storms, yet only by a minuscule amount as of right now. There continues to be a lot of uncertainty in how much moisture and instability there will be. This will need to monitored as it gets closer.



AVIATION
The marine layer continues to ebb and flow over North Coast terminals this evening with southerly flow dominating. High clouds continue to block IR satellite imagery of this feature, yet coastal observations continue to show that areas under the marine stratus will be foggy (Vis <1/2SM). Brief afternoon clearing to VFR with northerly winds are expected for coastal terminals and river valleys inland. Stratus is forecasted to return again.



MARINE
Northerly wind are expected to increase in the outer waters overnight to around 20 to 25 kt. These winds are strong enough to create small craft advisory conditions for the the outer waters due to steep short period waves in areas downwind of Cape Mendocino and Pt. St. George. Closer to the coast, high resolution models show southerly winds continuing through the evening. A small period southerly swell continues at around 3ft@17s.

Through the day, the northerly winds are expected to diminish as an upper level shortwave disturbance moves over NW CA which will likely cause the end to the small craft advisory. The southerly swell is expected to continue. High pressure briefly returns Tuesday and Wednesday which will increase northerly winds to around 20 to 25 kt.
Thursday and Friday, another upper trough is expected to flow over NW CA causing winds to diminish again with the potential for local southerly winds near the coast.



FIRE WEATHER
The main challenge for the fire weather forecast is the potential for thunderstorms. Monday afternoon a shortwave moves through, but at this point it still doesn't look like it things will line up for any thunderstorms. There may be some increased instability, but not enough moisture for any showers or thunder. Tuesday through early Thursday, weak high pressure is expected to bring dry and fairly stable conditions. Thursday night into Friday, another trough is expected to approach the area. At this point it is still hard to tell if the moisture instability and lift will line up to get thunderstorms, but it is possible. This will continue to be watched through the work week. MKK



EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 9 PM PDT this evening for PZZ470.

Small Craft Advisory until 9 AM PDT this morning for PZZ475.