textproduct: Eureka

KEY MESSAGES

* A cooling trend arrives Friday into the weekend.

* Chances for light rainfall for Del Norte and northern Humboldt Saturday.

* Elevated fire danger each afternoon through Saturday for the interior.

*Fire Weather Watch for Lake County Saturday for strong winds and low relative humidity.

SYNOPSIS

Cooler temperatures Friday into the weekend. Light rain is possible for the northern half of the area Saturday. Westerly to northwesterly winds will increase the fire risk for the interior through Saturday.

DISCUSSION

Interior temperatures will will be over 10 degrees cooler Friday as troughing from the NW begins to influence the region. The trough and associated front will swing through on Saturday, considerably lowering interior temperatures to the 70s and 80s.

Chances for rainfall have waned a bit as models trend this slightly northward, but still the chance for measurable rain is around 75% for much of Del Norte and around 20% in northern Humboldt north of Eureka. The chance for wetting rain (0.1" or more) in Del Norte is around 50% and around 10% in northern Humboldt County. The trough will contain modest instability, brining chances of some thunderstorms for Del Norte County.

Post frontal westerly winds will strengthen Saturday afternoon to the eastern portions of the area. The probability of wind gusts over 30 mph are above 50% for much of Lake County, eastern Mendocino, and the Trinity River Valley in eastern Trinity County. This will elevate fire weather concerns, particularly over Lake County where the strongest winds will coincide with dry conditions. A Fire Weather Watch has been issued to highlight this threat. See the Fire Weather section below.

High pressure is likely to return again early next week, returning near- normal temperatures and dry weather to the area. /JB

AVIATION

Fog to locally dense fog of 1/4 SM or less VIS settled into the coastal terminals Thursday night. A weak disturbance introduced some light drizzle and deepened the marine layer somewhat. Ceilings are varying a bit, but period of fog are still likely through Friday morning. The influence of an approaching trough is then expected to allow for improvement in CIGs and VIS, with perhaps scattering in the 20Z to 22Z span Friday. The stratus will fill back in Friday evening, but chances for fog are currently lower due to likely further deepening of the marine layer. Interior locations will remain VFR with gusty north to northwesterly winds developing in the afternoon.

MARINE

Northerly winds increase across the southern waters Friday while easing some in the northern waters north of Cape Mendocino. Localized gale conditions can be expected around and south of Cape Mendocino Friday afternoon through Friday evening. Short period seas up to 11 ft will be generated in the cape area from these winds. Winds and seas quickly ease Saturday as a trough moves in. This will bring thunderstorm chances to the northern waters, mainly closer to the Oregon border.

FIRE WEATHER

Troughing Friday into the weekend will return cooler temperatures and a deeper marine layer. Afternoon westerly to northwesterly winds will increase further Friday and especially Saturday. A weak front Saturday morning and early afternoon might support wetting rain for Del Norte County, but elsewhere, the only impact will be cooler weather, more cloud cover, and especially gusty onshore winds. Wind gusts of 30 to 40 mph are possible in Lake, southern Mendocino, and eastern Trinity Counties Saturday afternoon. RH will rise with this onshore push of winds from the 20s to the 40s, so the fire threat will be subdued somewhat. Still, elevated to locally critical fire conditions are expected, especially for the eastern portions of the area where RHs will rise slower. A Fire Weather Watch has been issued Saturday for lake County. /JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 4 AM Friday to 3 AM PDT Saturday for PZZ455.

Small Craft Advisory until 3 PM PDT Friday for PZZ470.

Small Craft Advisory until 3 AM PDT Saturday for PZZ475.