textproduct: Eureka

SYNOPSIS

Drying and warming weather today and Tuesday. A series of large swell will bring dangerous breaking waves along the west and northwest facing beaches this week. Confidence continues to increase for a moderate Atmospheric River (AR) impacting Northern California Friday into the weekend, bringing periods of heavy rainfall, high- elevation heavy snow, and strong south winds.

EXTENDED DISCUSSION...(Friday through the weekend)

There continue to be strong signals in ensemble and deterministic models for a good chance of widespread early winter weather late in the work week and weekend. CW3E Tools for GEFS and ECMWF EPS indicate there is a 75-85% chance of IVT greater than 500 kg/ms impacting the area Friday into the weekend. The Atmospheric River (AR) impacting Northern California Friday into the weekend, have the potential to bring periods of heavy rainfall, high- elevation heavy snow, and strong south winds. NBM chances for 72 hr storm total precipitation, Friday through Sunday, of over an inch are near 100% north of Cape Mendocino and 70% in southern Mendocino and Lake. NBM chances for over 3 inches of precipitation are over 90% in Del Norte and around 50% north of Cape Mendocino with much lower chances (30% or less) in Mendocino and Lake. High elevation areas of Del Norte and the King Range could see over 6 inches total. Rapid rises in small streams and rivers, minor flood impacts to urban areas, and debris on roadways are all possible. NBM is also showing high chances for wind gusts of over 40 mph over exposed ridges and coastal headlands with small (~20%), but nonzero, chances for winds this strong essentially everywhere across the area. Impacts will become clearer as the storm track solidifies in the coming days. /ZVS

AVIATION...06Z TAF

Post frontal conditions mixed with increasing dry, offshore flow has generally mixed out any marine stratus, allowing for generally VFR conditions all across the area. Some periods of MVFR visibilities are possible (35% chance) overnight due to low level fog formation, but anything more than that is highly unlikely. Mostly VFR conditions will persist Monday alongside moderate north breezes. There is a slight chance (20%) of a return of localized LIFR ceilings along the coast Tuesday night, but generally VFR conditions remains most likely (80% chance). /JHW

MARINE

Broadly hazardous conditions currently exist throughout the marine waters. Strong north wind shave built in, especially in the southern inner waters with some gusts over 36 kts, helping to build steep short period seas over 10 feet. Additionally, a steep long period westerly swell has built in and will peak early Monday around 18 feet at 16 seconds. Such hazardous conditions will persist into the early afternoon with both the swell and winds subsiding into Tuesday. Mostly calm winds are expected through the day Tuesday, but a fresh long period westerly swell up to 13 feet will keep the sea state elevated into Wednesday. After a brief lull around Thursday, strong winds and a series of steep westerly swells will return Friday through the weekend as a series of rainstorms cross the area. /JHW

BEACH HAZARDS

A large long period westerly swell has built across the coastal waters with waves registering up to 18 feet at 16 seconds. Such waves are capable of producing beach runup in excess of 22 feet. This is most likely the highest surf height of the season so far and will be particularly hazardous on west facing beaches where short period wind waves are calm (such as near Suemeg and Pt. Arena) where waves are most likely to manifest as unexpected sneaker waves. This risk will be greatest Monday morning. Surf will generally decrease through mid week but will remain elevated through Wednesday as another swell build in. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... Beach Hazards Statement until 10 AM PDT Monday for CAZ101- 103-104-109.

Frost Advisory until 10 AM PDT Monday for CAZ108.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 PM PDT Monday for PZZ450-470.

Small Craft Advisory until 3 PM PDT Monday for PZZ455.

Gale Warning until 11 AM PDT Monday for PZZ475.