textproduct: Eureka

KEY MESSAGES

* Moderate risk for sneaker waves along the Lost Coast and Mendocino Coast through Wednesday.

* Elevated fire danger today and Tuesday for interior areas due to breezy afternoon winds.

* Hot temperatures return late week into the weekend.

* Coastal stratus likely to form each night and clear each afternoon through at least the middle of the week.

SYNOPSIS

Near to slightly below normal temperatures are likely for the interior areas, while near to slightly above normal coastal temperatures are likely continue through Wednesday. Breezy afternoon winds elevate fire danger in eastern Trinity, eastern Mendocino, and Lake counties. Hot interior temperatures return late this week.

DISCUSSION

Warmer coastal temperatures may continue through Wednesday this week. This is highly dependent on the persistence of stratus into the afternoon and how early northwesterly winds start. A weak marine inversion will allow for at least partial, if not full, clearing in the afternoons. The Mendocino Coast will see breezier afternoon winds which will support closer to normal temperatures.

The troughing pattern has also brought breezy afternoon wind gusts of 20 to 30 mph in the interior areas, mainly in the higher elevations and channeled terrain (such as Clear Lake and the Trinity River valley). Low afternoon relative humidities in Trinity, eastern Mendocino, and Lake Counties along with these winds brings an elevated fire weather threat.

There is high confidence in high pressure rebuilding over the area later this week. NBM is showing moderate to high probabilities for high temperatures in the triple digits for most interior valleys starting Friday and continuing into next week. Currently, minor to moderate HeatRisk is expected. /JB/JJW

AVIATION

Stratus has started to erode from the coast late this morning, bringing VFR conditions to all areas. Occasional MVFR impacts are possible for the coastal terminals this afternoon from lingering stratus, but generally skies are expected to be mostly clear. Stratus returns this evening and overnight bringing IFR to MVFR ceilings. Some models do show lower ceilings and possibly fog to the coastal areas, but confidence in that is generally low. Breezy northwest winds are likely in the interior areas this afternoon and evening. /JB

MARINE

The sea state is dominated by a small 3 to 5 foot long period southerly swell and some small mid period westerly and northerly swells. A second reinforcing long period southerly swell will arrives Tuesday. Winds will remain very light, only up to 4 to 8 kts north of Cape Mendocino. Northerly winds strengthen 15 to 20 kts, locally up to 25 kts around the cape this afternoon. Northerlies trend higher in all waters starting Tuesday. Localized areas of gale conditions will develop in the expansion fan around Cape Mendocino. /JJW

FIRE WEATHER

Breezy westerly winds will continue in the afternoons today and Tuesday for interior areas and may be particularly breezy with gusts of 20 to 30 mph over the ridges and channeled terrain in eastern Trinity, northeast Mendocino, and Lake Counties. These areas are forecast to have low afternoon RHs in the teens and 20s. Localized and brief critical conditions are possible with these low RHs and winds. Overnight recoveries are expected to be good aside from the higher elevations of Lake and eastern Trinity County.

Closer to the coast, a deep marine layer brings high RH and perhaps stratus and/or fog into the river valleys overnight. Afternoon RH ranges from 60s to 80s near the immediate coast to 20s to 40s in interior Humboldt, Del Norte, and western Mendocino Counties.

Ridging rebuilds later this week into the weekend bringing much warmer high temperatures to the interior with most valleys forecast to reach the high 90s and triple digits. Afternoon RHs will again be in the teens and 20s for the eastern interior. Weak shortwaves arrive over this same period which may support some breezier afternoons along with this heat and low afternoon RH. Confidence is low at this time, but elevated fire weather conditions are again possible. /JB

BEACH HAZARDS

A long period southerly swell with periods up to 20 seconds remains in from tropical systems in the Eastern Pacific. A second reinforcing long period southerly swell will arrive Tuesday. These energetic swells will bring a low to moderate risk of sneaker waves that would be most hazardous on steep, south and southwest facing beaches along the Lost Coast and Mendocino Coast.

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 there recently. Stay safe and never turn your back on the ocean! /JJW

EKA WATCHES/WARNINGS/ADVISORIES

CA... Beach Hazards Statement through Wednesday afternoon for CAZ104-109.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 1 PM PDT Tuesday for PZZ455.

Small Craft Advisory until 9 PM PDT Wednesday for PZZ475.