textproduct: Eureka

SYNOPSIS

Midlevel clouds and cool, moist marine air will continue to build across the area Saturday. A cold front and widespread wetting rain will sweep across the area Sunday into Monday, mostly focused on the North Coast. Cooler and wetter weather will continue most of next week.

DISCUSSION

Low pressure slowly building alongshore has turned winds more westerly. This has brought much cooler and more moist marine air inland. Patchy fog has settled all along the North Coast and in near coital valleys, though passing waves and mid level clouds will continue to regularly disrupt the fog overnight. Highs will continue to cool Saturday aided by increasing midlevel clouds. Though mist will persist, dense fog will be less likely Saturday night into Sunday as instability and wind begin to increase.

There is high ensemble confidence that a deep trough and strong surface cold front will sweep across the area Sunday into Monday. This front will be focused on the northern half of the area and into Oregon. Widespread wetting rain is expected along the front, though there is still a good amount of uncertainty regarding amounts due to variability in the moisture plume strength and duration, particularly for the southern half of the area. That said, ensembles consistently place the area in the range for a weak atmospheric river with only very limited high end potential.

Though uncertainty persist, ensembles have increased in consistency over the past 24 hours. Most likely rainfall amounts vary from about 0.5 to 1.0 inches at low elevations in Humboldt County and 1.0 to 1.5 in Del Norte. Most likely ranges are greater at higher elevations generally 1.5 to 3.0 inches along near coastal ridges. Rain amounts will be less further south with most likely ranges of 0.1 to 0.4 inches for most of Mendocino and Lake Counties. There is a 15% chance of some wind gusts over 45 mph right along the coast, but any such winds would be very isolated to just the frontal passage itself Sunday afternoon.

Much colder air will move in behind the front. Snow levels will most likely drop to around 3000 feet by mid next week, but there will most likely be too little moisture at that time to support strong snowfall, with less than an inch or two at any highway passes. Any additional rainfall next week shows very little confidence in specific timing and amount. Broadly speaking, there is a slight chance of light rain focused on the southern half of the area around SUnday. There is moderate agreement (60% chance) for a stronger, widespread round of rain around next weekend. All that said, there is very high ensemble agreement in a generally colder and more moist pattern through at least mid month with additional waves of rain likely over the next couple of weeks. /JHW

AVIATION

(06Z TAFs)..LIFR conditions with low ceilings and visibility in BR/FG have been impacting the coastal terminal, with a shallow marine layer along the coast and adjacent coastal areas. Otherwise, variable conditions are expected for the coastal terminals with increasing mid to high-level clouds. High-res model guidances low clouds and patchy fog lifting and scattering out around mid morning on Saturday, resulting in VFR conditions with BKN- OVC mid to high level clouds. A frontal system is forecast to approaches Saturday night and Sunday. South winds are expected to increase to 10-15 kts at KCEC after 18Z, while light SSW winds up to around 5 kts will persist at KACV. Meanwhile, prevailing VFR conditions at UKI, with very light and variable winds are expected to continue through the next 24 hours. /ZVS

MARINE

As of 10 PM PST, buoy observations indicates the larger westerly swell around 10-11 feet at 14-15 seconds. This swell is expected to gradually subside tonight into Saturday afternoon. A forerunner westerly swell arrives Saturday evening, keeping seas elevated. South to southeast winds will increase to 10-20 kts overnight and through Saturday, with the strongest winds North of Cape Mendocino. Winds are the expected to strengthen and expanded into the southern waters on Sunday as frontal system approaches. Northerly winds are expected to return Sunday night in the wake of the front, before becoming moderate to strong breezes early next week. /ZVS

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PST early this morning for PZZ450-455-475.

Small Craft Advisory until 3 PM PST Sunday for PZZ470.