textproduct: Eureka

SYNOPSIS

High pressure continues to build into the area bringing warmer and dry conditions through the week. Some of the more protected northern valleys will see night and morning low clouds and fog limiting warming.

DISCUSSION

High pressure remains fairly flat over the west coast. As the inversion strengthens, inland valleys should expect morning fog this week. Between the low clouds and time of year, these valleys will have trouble warming each day as compared to other inland locations. The ridges are expected to be warmer and dry.

This pattern is expected to continue through the work week. There will be some subtle changes. In the valleys the inversion may get slightly shallower, but the valleys are still expected to have RH reach 90 to 100 percent each night. This may also create poor air quality with any locally generated pollutants getting trapped. The valleys, especially the ones seeing fog, will likely struggle to warm up. So far these have been only reaching around 50 degrees. Over the week they will likely get slightly warmer, but there is high uncertainty on how much warmer they will get. Temperatures in these valleys have been adjusted to well below what the NBM is forecasting as a result.

The higher terrain will likely see low RH both overnight and in the afternoons. The dry air at the higher elevations is generally expected to persist through the week. These higher elevations will also see warmer temperatures, likely in the 60s or even near 70 by the middle of the week.

The next chance for rain is not until the 21st or 22nd of January. This is a long ways out, but the NBM has remained consistent in showing this since yesterday. MKK

AVIATION...(06Z TAFs)

Shallow humid layer nearshore will most likely (70% chance) result in occasional IFR visibility and sky obscuration into early Monday morning, especially around Humboldt bay and near KACV. Confidence is not high due to light E-NE flow which will most likely result in a high degree of variability. Areas of IFR over the waters or right near the shoreline may impact terminals through 18-20Z Monday. Probabilities for longer duration IFR increases Monday evening and overnight at coastal terminals. Otherwise, fog and LIFR ceilings in the valleys of Trinity, Humboldt and northern Mendocino counties will clear out by noon on Monday and VFR is forecast to prevail for the afternoon.

MARINE

A long period westerly swell around 10 feet will continue to be a hazard to mariners in small craft through Monday evening. An advisory for hazardous seas remains in effect. Northerlies will increase to gentle to moderate breezes on Monday, especially south of Cape Mendocino. Highest chance for gusts from 25 to 30kt will be near and just downwind of Cape Mendocino. A brief lull is forecast on Tuesday before northerlies strengthen to strong breezes on Wednesday. Highest chances (70%) for gusts from 25-30 kt will be near and downwind of Cape Mendocino and over the northern outer waters. Gale gusts > 34 kt are less certain with chances around 30%. Large steep northerly waves from 8-10 feet will likely develop by Wed afternoon and evening and seas will become quite hazardous for small craft. Strong northerly breezes and large steep northerly waves will continue into Thursday, especially in the outer waters.

BEACH HAZARDS

A long period westerly swell is forecast to peak around 12 ft at 16 seconds by early Monday morning. The swell will decay through the day on Monday and will continue to pose a threat for wave runup and sneaker waves through Monday evening. A Beach Hazard Statement remains in effect for this moderate risk. Another long period swell group with peak energy near 17 seconds will build on Wednesday. This swell appears less energetic but may still result in a threat to beachgoers. Stay much farther back from the ocean and avoid steep beaches and jetties. Remember, never turn your back on the ocean!

EKA WATCHES/WARNINGS/ADVISORIES

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

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 PM PST Monday for PZZ450-455.

Small Craft Advisory until 3 AM PST Tuesday for PZZ470-475.