textproduct: Eureka

SYNOPSIS

A weakening frontal system continues the chance for rain showers through Tuesday. Widespread rain is expected late Tuesday night into Wednesday followed by lingering showers into Thursday. Mountain snow and coastal small hail is possible Wednesday night and Thursday morning.

DISCUSSION

Light rainshowers have arrived to the area, with a band of precip. focused primarily on northern Humboldt and Del Norte. Rain rates have remained light to locally moderate in mountainous terrain. High resolution models show showers mainly for Del Norte, Humboldt, and Trinity counties, though a few isolated showers are still possible for Mendocino and Lake. These showers are likely to remain light,and little to no impacts are expected.

A stronger frontal system moves through the PacNW Tuesday night through Wednesday. Southerly winds will increase ahead of the main frontal passage Wednesday morning. Much of elevated terrain of Del Norte and the higher terrain in Humboldt have over 50% chances to see gusts over 40 mph. Localized gusts of over 50 mph are possible over the highest terrain. Lake County may also see strong gusts, with a broad 20% chance for gusts over 40 mph at lake level. The higher elevations, including the Cobb area, have much higher probabilities.

Widespread light to moderate rain is likely across the area. Periods of heavy rain are possible for the North Coast, and especially in the King Range and the mountains of Del Norte and northern Humboldt. Total rain amounts range from around 2.0-3.0" in Del Norte, 1.0-2.0" in Humboldt and Trinity Counties, and 0.25-1.00" in Mendocino and Lake Counties. This will largely be beneficial rain, but some minor impacts (flooding in poor drainage areas and mud/rock slides) are possible in Humboldt and Del Norte with the heaviest rain. Snow levels will drop with this system, down to 5,000-5,500 ft Wednesday morning during the period of most precipitation. This will bring some snow down to Scott Mountain Pass. Snow totals there range from around 3 to 6 inches, depending on how low snow levels drop.

Snow levels continue to drop into Thursday, and could be as low as 2,500 ft as stratiform rain turns showery. While precipitation is likely to be meager by this point, some light snowfall is possible on the highest passes of Highways 3, 36, 199, and 299. A Winter Weather Advisory has been issued for the Trinity Horn above 4000ft due to melted snow freezing overnight while snow level plummet, creating icy, hazardous roads.

Additionally, with much colder air aloft, atmospheric instability will increase, particularly along the coast. Showers capable of producing accumulating small hail are possible, along with isolated thunderstorms. Much cooler temperatures are expected Friday morning with widespread near-freezing or freezing temperatures. Temperatures will generally trend warmer as high pressure begins to rebuild into the weekend. JB

AVIATION...(31/06Z TAFs)

VFR conditions with mid- to high-levelclouds prevail across all TAF sites. Nevertheless, there is the potential for MVFR ceilings with VCSH for the coastal terminals from 31/07Z through 31/21Z. CAMs suggest there will be an increase of showers activity from 15Z through 20Z. Meanwhile, mostly VFR conditions in UKI through 20Z, before ceilings lowering to MVFR. Another frontal system will bring an increasing chances of precipitation after 01/05Z for all TAF sites. /ZVS

MARINE

Northerly winds continue to diminish overnight, before becoming northwest to west winds early Tuesday. Winds will shift to southerly Tuesday afternoon and strengthen Tuesday night through Wednesday as a front approaches from NW. Winds are expected to peak to strong to near-gale south winds across the northern waters Wednesday morning, while mostly moderate breezes flow over the southern waters. Isolated gale force gusts are possible near PT St George by Wednesday morning. Robust westerly winds will rapidly develop behind the front Wednesday afternoon and then shift to northerly early Thursday.

Seas will continue to subside through Tuesday morning as northerly winds diminish. Seas will remain below 5 feet through Tuesday night, before a period of steep wind waves builds on Wednesday in the northern waters. A large steep northwest swell will begin to build in Wednesday night and peaking to around 10-14 feet at 12 seconds on Thursday. /ZVS

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 5 AM to 3 PM PDT Wednesday for PZZ450.

Small Craft Advisory from 2 AM to 10 PM PDT Wednesday for PZZ470.