textproduct: Eureka

KEY MESSAGES

* High pressure builds through the rest of the week, bringing an extended dry period with interior valley high temperatures warming into the 80s and 90s.

* An arriving long-period west-northwest swell brings an elevated risk for sneaker waves along the shoreline.

SYNOPSIS

Upper-level ridging builds over the West Coast this week, supporting a progressive inland warming trend and dry conditions through this coming weekend.

DISCUSSION

Broad mid-level ridging over the eastern Pacific will expand inland Tuesday through Friday, establishing high confidence in dry conditions across the region.

At the surface, the onshore pressure gradient between the offshore eastern Pacific high and the interior thermal low will drive fresh northerly winds along shore, strongest south of Cape Mendocino. Additionally, conditions will be gusty for many locations across Northwest California. Gusts greater than 20 mph could be possible Tuesday afternoon/evening with an 80% chance or higher for coastal areas from Del Norte to Mendocino, and more widespread chances for all of southern Humboldt and most of Mendocino and Lake counties, and for the ridges of Del Norte and Trinity counties. There is an 80 percent chance or higher for gusts over 25 mph for all coastal areas along with the King Range, with more widespread chances for Tuesday evening.

Strong atmospheric sinking beneath the upper ridge will steadily warm the air mass aloft. Thermal profiles across interior valleys will support afternoon maximum temperatures climbing into the 80s and 90s mid-week. Ensemble guidance highlights an 80% probability of interior valley highs exceeding 90F Wednesday and Thursday.

AVIATION

Gusty winds kept the terminals clear for most of the evening Monday but overnight there could be a few areas with light or patchy stratus coverage. As the mid level ridge set in there will be more drying and subsidence, and the soundings do show inversions at low levels. A mist or haze at various heights may be visible during Tuesday morning. Winds do switch bearing from southerly to easterly and finally northerly by Tuesday afternoon, with light winds the variation will not be as dramatic for flight safety. Due to an ongoing ASOS communications outage at KUKI, automated observations are unavailable and amendments are not scheduled.

MARINE

Fresh northerlies continue due to the pressure gradient between offshore high pressure and the interior thermal trough.

* Northern Inner Waters: Northerlies of 10 to 20 kt will generate steep short-period seas. A west-northwest swell at 15 to 17 seconds arrives today. A Small Craft Advisory remains in effect through Tuesday morning.

* Northern Outer Waters: Northerlies of 20 to 25 kt with gusts to 35 kt (mainly in the lee of Cape Blanco) will build combined seas to 10 to 11 ft. A Small Craft Advisory remains active through Tuesday morning.

* Southern Inner Waters: Fresh to strong northwest winds of 20 to 25 kt with gusts to 35 kt (mainly in the lee of Cape Mendocino) will maintain steep seas. A Small Craft Advisory remains in effect through Tuesday morning.

* Southern Outer Waters: Gale force conditions develop in the lee of Cape Mendocino, where northerly winds of 25 to 30 kt with gusts up to 40 kt will yield steep, hazardous combined seas of 11 to 12 ft. A Gale Warning remains in effect this afternoon through Wednesday morning.

BEACH HAZARDS

A long period west northwest swell at 3 to 6 ft with a period up to 17 seconds is likely to diminish into Tuesday, also lowering the threat of sneaker waves. The smaller period south swell will continue to persist through Tuesday despite not being as impactful. It is still in all beachgoers and water recreationalists to use caution, especially on south facing beaches. High astronomical tides will increase the danger, especially over rocks and jetties.

Sneaker waves are a unique hazard, with up to 30 minutes between waves. Large, unexpected waves can sweep across the beach without warning, sweeping people into the sea from rocks, jetties, and beaches. These sneaker waves can also move large objects such as logs, crushing anyone caught underneath. Even ankle to knee deep water can knock you down and drag you out when a sneaker wave hits. Pay attention and stay above the high water line and any wet sand to stay safe. If the ground is wet, waves have surged.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT Wednesday for PZZ450- 470.

Small Craft Advisory until noon PDT Tuesday for PZZ455.

Gale Warning from noon to 9 PM PDT Tuesday for PZZ455.

Gale Warning until 3 PM PDT Wednesday for PZZ475.