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.

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

* Widespread gusty winds with gusts from 20 to 25 mph expected today; wind prone areas of coastal Del Norte and the King Range could see gusts up to 35 mph today and tomorrow.

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 today 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 this 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, also, an 80 percent chance or higher for gusts over 25 mph for all coastal areas along with the King Range and higher elevations of interior southern Mendocino and Lake counties. This afternoon and tomorrow afternoon, just along the Del Norte Coast north of Pt St George and the King Range have over a 70 percent chance for gusts over 35 mph.

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 a 75% to 90% probability of interior valley highs exceeding 90F Wednesday through the end of the week (this mostly includes the Trinity River Valley, the warmest valleys of southern Humboldt and southern Trinity counties, interior valleys of Mendocino and Lake counties).

AVIATION

Gusty northerly to northwesterly winds will surge this afternoon for many terminals in Northwest California. Gusts from 20 to 30 knots could occur for many coastal terminals this afternoon. There could also be periods of low ceilings or visibility this afternoon/evening due to low to mid level clouds pushing up onshore with the winds. As winds diminish this evening, there is a chance for IFR/LIFR ceilings for coastal terminals and down coastal river valleys. It is more likely that low ceilings will form and linger around the Eel River Delta and Humboldt Bay late this evening and overnight. VFR conditions are anticipated for many interior terminals.

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 12 to 14 seconds continues today. A Small Craft Advisory remains in effect through Thursday 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 early Wednesday morning with a Gale Warning taking over until Thursday 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 Gale Warning has taken effect and will remain in effect through late this evening.

* 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 through Thursday morning.

BEACH HAZARDS

A long period west northwest swell at 3 to 6 ft with a period up to 17 seconds continues to diminish today, also lowering the threat of sneaker waves. The smaller period south swell will continue to persist through today despite not being as impactful. It is still in all beachgoers and water recreationists 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 9 AM PDT Thursday for PZZ450.

Small Craft Advisory until noon PDT today for PZZ455.

Gale Warning until 9 PM PDT this evening for PZZ455.

Small Craft Advisory until 6 AM PDT Wednesday for PZZ470.

Gale Warning from 6 AM Wednesday to 9 AM PDT Thursday for PZZ470.

Gale Warning until 9 AM PDT Thursday for PZZ475.