textproduct: Eureka

KEY MESSAGES

* Moderate to heavy rain and gusty south winds across much of the area throughout Friday.

* Very large surf Saturday with breaking waves over 25 feet is possible. This will increase beach erosion and possibly bring some coastal flooding.

* Additional rain and wind possible over the weekend and into early next week.

SYNOPSIS

A strong cold front is expected to bring gusty winds and moderate to heavy rain to the area starting late tonight and continuing through tomorrow. There may be a brief break in the rain on Saturday before another system brings more rain and wind Saturday night and Sunday.

DISCUSSION

A troughing pattern will move into the Pacific Northwest late this evening and will persist through early next week. Two cutoff low pressure systems are projected to affect Northwest California as this pattern takes hold. The frontal boundary associated with the first cutoff low will begin to impact the region by late tonight bringing strong southerly winds late tonight and early to mid morning tomorrow along with widespread moderate to heavy rain tomorrow morning. The next frontal boundary with the next cutoff low will approach the area late Saturday and bring more southerly winds and moderate rain, but is anticipated to be weaker than the first.

With the first front, southerly winds are forecast to ramp up by Thursday afternoon/evening starting first at coastal headlands and higher elevations near the coast of Del Norte and Humboldt counties. Several models show 55 to 65 kt winds aloft (at 925mb and 850mb) as the front moves into Humboldt and Del Norte counties. Lower levels could be unstable enough to enable the higher winds to mix down to the lower elevations, especially along the coast. Stronger southerly winds will begin this evening for coastal headlands and high terrain areas near the coast around Cape Mendocino and north. As the front progresses, stronger winds will impact most areas of Northwest California. The strongest winds are forecast for Del Norte County along with the King Range in Humboldt County. A High Wind Warning has been issued for the Del Norte Coast from midnight tonight and last through 1pm Friday. Wind Advisories have been issued earl Friday through early Friday afternoon for interior Del Norte; the immediate coast, coastal headlands and higher terrain areas of Humboldt county; coastal headlands and higher terrain areas of northern Mendocino County; and higher terrain areas of eastern Lake County.

Moderate to heavy precipitation is expected through the day Friday, with showers likely through Saturday and the potential for another bought of moderate rainfall on Sunday. Light rain will most likely start very late tonight or very early Friday morning on south facing slopes of the King Range. The heavier, main band of rain is forecast 2 to 3 hours before sunrise on Friday morning. The National Blend of Models (NBM)indicates over an 85% chance of total rainfall amounts of 2 inches or more for Del Norte, most of Humboldt, northern and western Trinity, and northern Mendocino and over a 75 percent chance for 1.5 inches or greater during the same time period for central eastern Trinity, southern Mendocino, northwestern Lake counties with southeastern Lake most likely seeing close to an inch. The Humboldt Bay region has about a 65 to 75 percent chance of rainfall totals of 2 inches due to a rain shadow effect.

Behind the front showers are expected, especially in Humboldt, Del Norte and northern Mendocino counties. The heavier showers may bring close to an additional inch of rain with them. There is the potential for some thunder with these showers as well The NBM thunder probabilities have come down slightly, but are still around 15 to 20 percent.

Generally dry weather is expected on Saturday, although there may be some lingering showers. This will be short-lived however with the next weather system moving in Saturday night or Sunday. This one is expected to have lighter winds and rain, but still could see a half inch in Lake county to nearly two inches in the mountains of Humboldt and Del Norte counties. Drier weather is possible Monday and part of Tuesday with another system possible later on Tuesday. /JLW

AVIATION...(18Z TAFs)

A strong cold front moves through the area tonight into Saturday morning, bringing widespread moderate to heavy rain. IFR to MVFR ceilings and visibility reductions are expected as the front moves through the area. Gusty south wind builds this afternoon and continues overnight, as well, with gusts exceeding 40 kts likely at CEC and may exceed 40 kts at ACV. LLWS is likely as winds 1500-2000 ft AGL remain much stronger at 45 to 50 kts. Steady rain turns showery by late Friday morning. Thunderstorms are possible within the strongest showers, especially along the coast, and bring brief periods of erratic, gusty winds, and small hail. Rain showers continue through Friday evening, bringing occasional MVFR to IFR ceilings and visibilities. JB

MARINE

South winds continue to build today as a strong frontal system approaches the area. Gale to storm force gusts are likely, with the strongest winds in the northern waters. With some instability with the front and 925 mb winds exceeding 60 kts, some isolated 60 kts wind gusts are possible as the front passes Friday morning. Localized gusts exceeding 60 kts are possible in the far northern waters. Meanwhile, seas will be elevated as a 11 to 13 foot mid period westerly swell has moved into the waters. These will combine with southerly wind waves of 8 to 14 ft, with the highest seas in the northern waters, creating a very confused sea state. By 10 AM Friday, the front will have moved through and winds turn more westerly. Steady, heavy rain, will transition to rain showers. Instability increases behind this frontal passage, which will possible thunderstorms with localized gale force gusts, heavy downpours, small hail, and isolated waterspouts. Thunderstorm chances continue through Friday afternoon and evening, then ease overnight.

A very large NW swell of 26-29ft@18sec is forecasted to arrive Friday night into Saturday morning. Expect hazardous conditions to continue through the weekend with the increased potential for a hazardous seas warning to follow the gale and storm warnings. Saturday night, a second cold front is forecasted to pass over the area once again creating strong, likely gale force winds for the coastal waters into Sunday morning. Another large swell of 21- 23ft@18sec is also expected to arrive Sunday afternoon lasting into Monday. Expect continued storms through next week as the storm track looks to remain fixed over our area through Wednesday at the earliest. JB/DS

BEACH HAZARDS

Just as strong winds and shower activity diminish on Friday afternoon, a very large swell is expected to arrive to the shoreline. Global wave models shows this swell building to around 25-28 feet at 18 seconds. This could lead to breaking wave heights of up to 35ft. A High Surf Warning has been issued north of Cape Mendocino from 1pm Friday (11/13) to 4am Sunday (11/15) and south of Cape Mendocino from 4pm Friday (11/13) to 4am Sunday (11/15).

A second large swell at 19-22 feet at 17 seconds is forecast to arrive late Sunday into Monday. This will likely warrant another high surf advisory with breaking waves of up to 25 to 30 feet.

High surf in northern California can be very dangerous. It is recommended to stay away from jetties, exposed rocks, steep beaches, and the waterline in general during these events. Large waves can rush up the beach knocking down individuals. Very large logs and tree stumps can also be carried by the waves adding to the hazards on the beach. Low lying parking lots next to beaches could see water inundation and bluffs may be subject to coastal erosion during the peak swell Friday night. Please remain safe and avoid beaches, jetties, and bluffs during periods of high surf.

COASTAL FLOODING

Water levels inside Humboldt Bay continue to run 1.5 to 2.2 feet over the astronomical tides. The max high tide is expected to drop each day through the end of the week and into the weekend, yet stronger southerly winds and a large westerly ocean swell of over 25 feet on Friday will likely offset at least some of this decrease in max tide height. A Coastal Flood Advisory has been issued for areas around Humboldt Bay from 11am to 3pm Friday. The water levels are expected to be slightly below 8.8 feet the next couple of days around high tide (11/13 @1:04pm, 11/14 @1:45pm).

EKA WATCHES/WARNINGS/ADVISORIES

CA... High Wind Warning from midnight tonight to 1 PM PST Friday for CAZ101.

High Surf Warning from 1 PM Friday to 4 AM PST Sunday for CAZ101-103.

Wind Advisory from midnight tonight to 1 PM PST Friday for CAZ102>106.

Coastal Flood Advisory from 11 AM to 3 PM PST Friday for CAZ103.

High Surf Warning from 4 PM Friday to 4 AM PST Sunday for CAZ104-109.

Wind Advisory from 4 AM to 11 AM PST Friday for CAZ109>111.

Wind Advisory from 7 AM to 2 PM PST Friday for CAZ119-120.

NORTHWEST CALIFORNIA COASTAL WATERS... Coastal Flood Advisory from 11 AM to 3 PM PST Friday for PZZ415.

Storm Warning until 6 AM PST Friday for PZZ450-470.

Gale Warning from 6 AM to 4 PM PST Friday for PZZ450-470.

Small Craft Advisory until 1 AM PST Friday for PZZ455-475.

Gale Warning from 1 AM to 4 PM PST Friday for PZZ455-475.