textproduct: Eureka

KEY MESSAGES

* Warmer interior temperatures continue today, before 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.

SYNOPSIS

Cooler temperatures return to the coast today and across the area 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

High pressure begins to weaken today as a trough moves into the Pacific Northwest. Weakened offshore flow has allowed for coastal stratus to form with fog being reported along much of the Humboldt and Del Norte coasts. Some clearing is possible this afternoon, but still this will bring a much cooler day to the coast than yesterday. Along with coastal stratus, high clouds and virga showers from the remnants of Hurricane Marie are streaming into the area. This produced a few showers and a few lightning strikes this morning. This potential has waned as the bulk of the moisture has moved eastward, but the high clouds have been helping cool the interior temperatures slightly.

Interior temperatures remain relatively warm today in the 90s to just over 100, but temperatures will cool significantly with the trough moves in, with high temperatures over 10 degrees cooler by Friday. By this weekend, much of the interior is forecast to be in the 70s and 80s with the coast in the low 60s. A weak front moving through the northern portions of the area will bring a chance for light rain to Del Norte and northern Humboldt counties. Chances 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.

Post frontal westerly winds will be breezy 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 as these winds will be especially strong; and relative humidities, while higher, will still be low in the afternoon. See the fire weather section below for more information.

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

AVIATION...(18Z TAFs)

Stratus and fog has remained persistent along the Humboldt and Del Norte coasts bringing LIFR conditions into the afternoon. An eddy off the coast has continued to reinforce stratus that does erode. Temporary scattering and visibility improvements are possible this afternoon, but LIFR to IFR conditions are likely to continue into the evening and overnight. Fog is likely again at the coastal terminals overnight with a shallow marine layer. Interior areas remain VFR with gusty northwesterly winds this afternoon. /JB

MARINE

Breezy northerly winds return Thursday, particularly in the lee of Cape Mendocino. Near gale force gusts are possible by Thursday evening in the lee of Cape Mendocino and Cape Blanco. Steep seas may propagate into the nearshore waters even as winds remain relatively light, especially south of Cape Mendocino. Winds ease Friday north of Cape Mendocino and Saturday south of the Cape as a weak front moves through the area. Strong northerlies return Sunday. Along with wind driven seas, a long period south swell from Hurricane Marie at around 2 to 3 ft continues through the waters. /JB

FIRE WEATHER

Much warmer and drier conditions continue today, although offshore flow has weakened and marine influence started to return. Slightly higher afternoon RH is expected today along with breezy afternoon winds. Because afternoon RH is still low (teens and 20s), breezy winds of 10 to 15 mph will bring elevated to locally critical fire weather conditions. The greatest threat will be in Lake County and eastern Trinity County in the lower elevations where terrain channeling will locally enhance winds.

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. /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.