textproduct: Eureka

SYNOPSIS

Snow, small hail and rain showers continue across the area into early Wednesday. A short break in the weather is expected Wednesday as the showers become more scattered. Rain and low elevation snow are expected to return Wednesday evening and continue through Thursday morning. Another break in the precip is expected Thursday afternoon through Friday before another strong storm system moves in for the weekend bringing rain, snow, and strong wind.

DISCUSSION

The cold upper level trough is continuing to bring showers to the area this evening. Many of these contain small hail as snow levels still hover around 1500 feet. late tonight, some of the snow levels may even drop down to sea level. A few flakes are even possible at the coast, although no accumulation is forecasted. Snow levels may drop to 500 or 1000 feet, although less precipitation and lighter snowfall amounts expected. Showers are expected to taper off this morning with a general break in the hazardous weather through much of the day. Late this afternoon/evening another wave of frontal energy should drop down from the northwest bringing more rain and snow. Snow levels are expected to be around 1500 to 2000 feet over the areas with levels as low as 500-1000ft for interior Del Norte, Trinity, and N. Humboldt Counties. There remains the potential for small hail along the coast.

Thursday afternoon shows diminishing showers and slightly higher snow levels before giving way to drier weather Thursday night and Friday. The dry airmass will be very cold, yet how much this is felt at surface will depend on the extend of cloud coverage. Overnight low temperatures may end up warmer than expected if there are more low clouds. A cold weather advisory may be needed for this time period when it gets closer.

Friday through early next week, models show a series strong weather systems moving through the area. Snow levels may start off around 1500 to 2000 feet and are expected to rise as it goes through the day on Saturday as heavier precip moves in. That said, snow levels often rise slower than the models predict so this will need to be watched over the next couple of days. Through the weekend, this event will be full of rain and possible flooding for Mendocino and Lake counties. The ensembles are showing higher IVT's with a 75% chance of exceeding 250 kg/m/s, however very little chance for over 500 kg/m/s. While this is not particularly strong, it looks like there will be multiple quick impulses that may overwhelm the rivers and streams. The exact timing of the breaks in rain will be a big factor in the level of impacts. Strong southerly winds are also expected with the strongest through Saturday night. The mean NBM 24 hour max gust shows around 40 to 50 mph at the lower elevations and the higher elevation wind gusts are showing over 70 mph.

AVIATION

VFR conditions and light surface winds have prevailed at the terminals through Tuesday evening. Random rain showers, intense and mixed with small hail at times, has occasionally resulted in MVFR ceilings from 1500-3000 feet and IFR vsby around 1 to 2 miles. That said, expect VFR to predominate through Thu. There is about a 50% chance for MVFR ceilings and a 20% chance for IFR vsby in more intense convection or showers at any given time. Winds will remain predominately light, 10 kt or less, with a 25% chance for gusts to 30 kt in showers.

MARINE

A large, steep, northwest swell is forecast through Wed. As of Tuesday evening, seas were still around 14 to 16 ft at 13 seconds which is borderline for a warning for seas. Winds shift to southerly or westerly on Wed and could gusts to 20-25 kt in the afternoon. A west wind surge is forecast to develop again after frontal passage Wed night, followed by periodic gale force N wind gusts for mostly the outer waters on Thu. Conditions settle down on Fri before a series of powerful frontal systems bring a moderate to high risk for gale or storm force winds Fri night through Sun night.

COASTAL FLOODING

High astronomical tides resulted in minor coastal flooding at high tide Tuesday, with the tide reaching 8.81 ft above MLLW with a surge around 1.5 feet. Applying the same anomaly for high tide Wednesday results in a tide of 8.6 to 8.7 ft MLLW at 11:45 AM at the North Spit tide gauge. Should the tide exceed 8.8 ft MLLW, minor coastal flooding is possible around Humboldt Bay, including the Arcata Bottoms and in King Salmon. JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... Winter Weather Advisory until 4 PM PST this afternoon for CAZ101-103.

Winter Storm Warning until 6 AM PST Thursday for CAZ102- 104>108-110-111-114-115.

Cold Weather Advisory until 7 AM PST this morning for CAZ113-115.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 10 PM PST this evening for PZZ450.

Small Craft Advisory until 3 AM PST Thursday for PZZ455-470- 475.

Gale Watch from late tonight through Thursday evening for PZZ470-475.