textproduct: Eureka

AVIATION...12Z UPDATE

A stratus deck has made its way to Humboldt Bay early this morning bringing MVFR conditions. A dry cold frontal boundary making southward through the morning will help mix this layer away leading to wide spread VFR conditions for coastal terminals. Northerly winds will build to gusts up to 30kts after this frontal passage. These winds have the potential to transport haze from large breaking waves along the coast over terminals, yet minimal degradation is expected. Inland areas can also expect VFR conditions with enhanced north winds. These winds are also capable of low level turbulence near terminals, especially during the peak of the afternoon. DS

PREV DISCUSSION

/issued 237 AM PDT Sat Oct 10 2026/

KEY MESSAGES...

* An incoming dry cold front will bring much cooler conditions by Friday and the weekend.

* Strong, gusty north winds expected close to shore, along ridges, and in channel terrain this weekend.

* No wetting rain forecast for the next 10 days.

SYNOPSIS...An incoming dry cold front will cause strong north winds through the weekend. Dramatically cooler temperatures are to be expected, with chances for frost or sub freezing temperatures for the interior through late next week. Chances for wetting rain remain near 0% through the extended forecast.

DISCUSSION...This weekend weather will be dominated by the impacts of an upper level trof entering the PacNW. While the center of this low pressure system will be farther north, over WA and OR, shortwave disturbances will flow over NW CA enhancing atmospheric mixing and leading to gusty conditions. Gusty north winds will be strong Saturday and Sunday with coastal areas and ridges experiencing the bulk of the flow. Higher resolution models also are showing these winds mixing down into river valleys that are exposed to the direction of flow. Wind speeds will be strong, between 25-35mph in the afternoon, while still remaining below levels needed for a wind advisory. Cooler temperatures are also expected with this feature through the weekend into early next week.

Besides the stronger winds, mornings are expected to be chilly. These colder temperatures have the potential to cause some localized frost for inland valleys. Confidence is high on temperatures dropping below 35degF for much of Trinity and NE Mendocino. That said, frost could be stopped by cloud development in these valleys as forecasted RH valleys above 95% are likely for most valleys besides those in NE Trinity County. Another feature that could limit frost formation is winds lasting overnight. Over the next 24hrs, it will become more clear on this threat as ground observations record the moisture flux to the area.

This coming work week, the trough that will impact this weekend's weather will move eastward over the Great Basin allowing for an upper level ridge to rebuild into the region. This rebuilding will show a warming trend back to above normal temperatures for inland areas, dry ridges, and overcast skies along the North Coast. Temperatures in the 80s are likely by midweek and could even break 90degF by the end of the coming week. DS

MARINE...An incoming dry cold front will continue to cause enhanced strong to gale force winds through the weekend. These winds will strengthen through today, with gusts to 40 kts. Near Storm force gusts will develop south of Cape Mendocino. Steep and hazardous short period seas of 12 to 15 ft are developing as a result. In addition to very steep short period seas, a moderate, very long period westerly swell will impact the waters around Sunday while gale conditions remain in the outer waters and around Cape Mendocino. Winds will gradually subside early next week while the long period swell very slowly weakens.

FIRE WEATHER...Close to record breaking ERCs exist for the area at this time of year today. An incoming dry cold front will also cause an unstable atmosphere leading to strong wind gusts for ridges and channeled terrain along the NNW flow. Winds will turn more easterly by early Sunday, further drying conditions and producing poor RH recovery at high elevations. That said, this cold front passage will cause conditions to be much more seasonably cool and moist (highs in 70s and RH around 30 percent). However, the lack of any rain chances and recent drying will still support near record breaking Burning Index values for October around Saturday. All of these factors together show that there is the potential for much above average fire activity through the weekend.

BEACH HAZARDS...The first long period swell of the season arrives this weekend. The west-northwest swell will arrive to Northern California this evening with a period over 25 seconds. Swell will then build through Sunday, peaking Sunday afternoon and evening at around 5 feet at 19 seconds. This very long period swell will result in a heightened chance for sneaker waves and run-ups of unusual size through Monday evening. A beach hazard statement has been issued for Sunday morning through Monday midday as a result.

While the threat for sneaker waves will be persistent throughout Sunday and Monday, the highest risk is expected during periods of incoming tides. With high tides along the California coast at around 11am to 1pm Sunday and Monday along N CA coast. A positive tidal anomaly is yielding tides around 1-1.5 feet higher than predictions on top of higher than usual tides, adding to the threat.

COASTAL FLOODING...A new moon lunar cycle is causing higher than usual tides. A positive tidal anomaly of 1-1.5 feet will yield high tides that will be near or even reach advisory levels of 8.8 ft for Humboldt Bay Saturday, Sunday, and Monday.

North Spit high tide estimates: Saturday: 8.5 ft at 12:03 P.M.; Sunday: 8.8 ft at 12:32 P.M.; Monday: 8.6 ft at 1:01 P.M.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Beach Hazards Statement from late tonight through Monday afternoon for CAZ101-103-104-109.

NORTHWEST CALIFORNIA COASTAL WATERS... Gale Warning until 4 AM PDT Sunday for PZZ450-455.

Gale Warning until 2 AM PDT Monday for PZZ470-475.