textproduct: Eureka

KEY MESSAGES

* Temperatures cooling to near normal today and slightly below normal Thursday before warming above normal once again for Friday and into the weekend.

* Breezy afternoon winds today and Thursday across Mendocino, Lake and Trinity counties. Local areas of low RH elevate fire danger, especially in Lake county.

* Possible thunderstorms across the interior next week.

SYNOPSIS

An upper level low off the Pacific Northwest will bring cooler inland temperatures, back closer to normal for the next several days. This will also bring some breezy afternoon winds in the interior. Above normal temperatures are expected to return for the weekend with another chance for thunderstorms next week.

DISCUSSION

The upper level trough off the Oregon and Washington coast is expected to bring slightly cooler temperatures and some breezy afternoon winds. Highs across the interior are expected to be in the mid to upper 90s. Some of the areas farthest inland such as Lake and eastern Trinity county will not see much cooling. This will bring onshore flow, likely keeping quite a few coastal clouds around. With the cooler air aloft the inversion may be slightly weaker which could allow some clearing in the afternoon at the coast. This is expected to increase afternoon winds slightly, especially in Mendocino, Lake, and eastern Trinity counties. See fire weather section for details. More significant cooling is expected on Thursday with highs in the 80s closer to the coast and near 90 farther inland. Stratus is expected to be more persistent with the onshore flow. Afternoon winds will be breezy once again.

Friday and into the weekend high pressure starts to push it's way back to the west as the low becomes an open trough and lifts to the north. The ensemble clusters indicate there is some uncertainty on how quickly this will occur. It looks like high temperatures, at least in Trinity county, will be above normal and close to 100 in the valleys for the weekend. This may bring some locally moderate heat risk. It looks like Mendocino and Lake county will remain cooler and closer to normal with highs in the 90s. Heat risk will remain in the minor level in these southern areas.

Early next week the models are showing a return of monsoonal monsoonal moisture. This will bring the potential for thunderstorms once again or least some mid and high level clouds. This will need to be monitored as it gets closer. Currently there are no thunderstorms in the forecast, but this may change. This will likely also bring some cooler temperatures. MKK

AVIATION

Stratus is expanding across the Humboldt and Del Norte coasts this morning. Some also may develop on the Mendocino later early in the morning, but confidence is low on this. Later this morning and into the afternoon the marine layer is expected to deepen and cigs are expected to lift some. The upper low approaching the Oregon coast is expected to weaken the inversion and may allow for afternoon clearing at the coast, although confidence is low on that. Tonight stratus is expected to be widespread again, although it may remain a bit higher ceilings IFR or close to that. MKK

MARINE

Conditions are expected to remain persistent through Friday. Northerly winds continue with the strongest winds in the lee of Cape Mendocino. A few gusts to 30 kt are expected just south of the Cape. Waves will mainly be wind driven, but there are a couple small swells. One out of the south to southwest around 2 feet at 14 seconds. The second small swell is expected to start to build in this morning at around 2 feet at 14 seconds.

The stronger winds pushing farther off the coast has slowed slightly with the winds remaining fairly steady through Friday night. Now it's looking Saturday will be the when the northerly winds start to push a bit farther offshore. It now looks like it will take until Sunday for much of the area to drop below 10 kt. These lighter winds are expected to continue into early next week. MKK

FIRE WEATHER

Wednesday afternoon, stronger northwest winds are expected in Mendocino, Lake, and eastern Trinity counties. Afternoon RH is expected to be low with teens and 20s expected for much of eastern Lake County and teens in Lake County and Trinity County. These winds and low RHs will elevate fire danger. The upside is these onshore winds will bring more moisture and RH will gradually rise. Winds continue to be breezy Thursday but higher afternoon RHs are expected with 20s and 30s in Mendocino, 20s in Lake County, and teens to 20s to eastern Trinity County. Winds ease Friday, but afternoon RH will also lower back into the teens and 20s. /JB/MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT Saturday for PZZ455-475.