textproduct: Eureka

KEY MESSAGES

* A general troughing pattern will bring additional light rain over the region tonight/Friday and periods of unsettled weather over the weekend.

* Overnight temperatures for the interior will turn chilly, bringing chances for frost Friday morning and through the weekend.

SYNOPSIS

Light rainfall chances continue this evening as a weak area of low pressure moves by. Overnight temperatures for the interior will turn chilly, bringing chances for frost Friday morning and through the weekend. A general troughing pattern will bring additional light rain chances over on Friday and periods of unsettled weather over the weekend.

DISCUSSION

A second colder and somewhat unstable area of low pressure will continue to move by the area today and tonight. This will continue the chances for showers and perhaps a couple of coastal thunderstorms.

As the environment attempts to clear out through Friday morning, much cooler overnight lows will develop for the interior. If clouds do clear out and fog does not develop, areas of frost will be likely for the interior. There is still some question on the amount of clearing or even additional light showers, especially with the numerous troughs forecast through the weekend. These will also bring a shot for some isolated thunderstorms. Despite the uncertainty, issued a frost advisory for southern Trinity, northeastern Mendocino, and northern Lake counties due to the forecast lows being in the mid 30s and the fact these cold temperatures are occurring so early in meteorological fall.

The broad upper low to the north will stall ahead of blocked flow through the weekend, with weaker shortwave disturbances rotating in. More at least weak troughing may redevelop behind it. This gives mixed signals for the extended outlook. There will look to be some sort of warmup early to mid next week, but if it occurs, it should be short lived if the troughs continue moving through. There are also questions about whether tropical moisture may stream northeast toward the region from decaying tropical systems well off the coast. Model guidance has a large variance in possibilities ranging from completely dry after Sunday to several chances of showers and possibly thunderstorms mid to late week.

AVIATION...(18Z TAFs)

Rain showers continue across portions of the region, particularly in the north in Humboldt, Del Norte, and Trinity counties. Ceilings have been variable, ranging from LIFR to VFR as the showers and cloud bands move through the area. Farther south the lower level clouds are now starting to clear out and VFR is prevailing at UKI. The occasional showers will and possibly a thunderstorm will continue along the Humboldt and Del Norte coasts into tonight with ceilings falling with each passing shower. Some areas of fog will be possible overnight into Friday morning.

MARINE

A trough from the north is bringing steep NW swell at 8 to 11 ft at 11 seconds to much of the waters. With buoys reporting over 10 feet a small craft advisory has been issued for waters north of Cape Mendocino through Friday morning. Otherwise winds will be light for most of the waters through Saturday. Then, northerlies will strengthen some through the weekend, mainly over the southern waters south of Cape Mendocino. The northerlies do not look to fully strengthen again until early next week. Hurricane Marie will deliver a long period southerly swell Saturday. Though small, at around 4 ft at 16 seconds, is a larger than typical swell from this direction.

BEACH HAZARDS

Hurricane Marie will usher in a long period southerly swell of 3-4 feet at 16 seconds for south facing beaches by Saturday into Sunday. Thus, there could be a risk of sneaker waves, especially if the swell comes in slightly larger.

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!

EKA WATCHES/WARNINGS/ADVISORIES

CA... Frost Advisory from 3 AM to 9 AM PDT Friday for CAZ108-110- 111-114.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 AM PDT Friday for PZZ450-470.