textproduct: Eureka

KEY MESSAGES

* Light rain showers are expected to become more widespread this morning before tapering off this afternoon and evening.

* Dry, cooler and breezy conditions are expected Friday with frost or freezing temperatures possible Friday night.

* There is the potential for a pattern change to cooler and wetter weather. This may start as early as Sunday or more likely hold off until early or mid next week.

SYNOPSIS

Rain showers continue through this afternoon and finally move out this evening and overnight. This will set up a cool and dry Friday with frost likely Friday night. Warm and dry conditions are expected Saturday. The next chance for rain for Humboldt and Del Norte being late Sunday into Monday.

DISCUSSION

An upper low off the Central California Coast continues to bring wrap around rain showers to the area. Shower activity continues through the morning and early afternoon across much of the area, outside of much of Del Norte. High resolution models are modeling a narrow band of moderate precipitation late morning and early afternoon in Humboldt and western Trinity Counties. A secondary moderate rain band may set up in eastern Trinity, eastern Mendocino, and eastern Lake in the afternoon. A stray thunderstorm is possible within these heavier showers, however confidence is low as persistent cloud cover may limit instability. Outside these narrow bands of rainfall, generally light rain is expected with some areas seeing no rain. Wetting rain (over 0.1") is likely for much of Trinity, Mendocino, and Lake Counties. Localized areas of over 0.5 inches are possible within heavier rain bands. The low quickly moves east of the area this evening and much drier air fills in behind. Behind the front areas that do manage to clear are expected to see valley fog. The chilly airmass could allow some areas to drop into the mid 30s and see localized frost, but with widespread rainfall, valley fog will limit cooling. Closer to the coast and above a couple thousand feet, the ridges are expected to clear out and see breezy easterly winds. Friday is expected to be see quite of drying, but temperatures are expected to remain in the 60s to low 70s. This drier air will set up the area for a chilly night Friday into Saturday morning. Easterly winds will likely keep the coast clear and the ridges dry.

Sunday and into early next week, the forecast remains highly uncertain. The models have backed off from the wettest solutions. However some of the model clusters continue to show a tenth to a quarter of an inch of rain on Sunday, mainly in the evening. NBM shows around a 35% chance for a tenth of an inch of rain Sunday night into Monday for Northern Humboldt and Del Norte. The models are still showing a fairly even split between a large ridge and trough over the area. This could mean a difference in interior high temperatures in the 50s in the trough or over 75 under the ridge. By Tuesday or Wednesday an increasing number of the cluster members showing a trough moving into the area bringing the potential for some rain. This will definitely be a time period to watch and may be the early signs of a more significant pattern change. JB/MKK

AVIATION...(6Z TAFs)

Stratus has formed off the Humboldt and Del Norte Coasts bringing LIFR impacts and fog to both coastal terminals. The upper low affecting the area will complicate the forecast and may disrupt the stratus layer at times. Models are showing high chances for stratus to last at least into the late morning hours, if not persisting through the afternoon. Rain showers may affect the coastal terminals at times, but the bulk of the rain will be over the interior areas. UKI will see rain showers peaking early to late morning with conditions improving over the day. MVFR ceilings and visibility reductions are possible within stronger showers. Showers taper off in the afternoon and evening. JB

MARINE

Northerly winds begin to increase today, especially by the afternoon as the upper low moves east of the area. Elevated winds and steep seas are anticipated today through Saturday with a 60 to 80 percent chance for widespread gale force gusts by very late today/early Friday to Friday afternoon. Seas will be dominated by these steep and hazardous wind waves and a decaying mid period westerly swell. Winds diminish Saturday into Sunday as a low pressure system approaches north of the area. JLW/JB

FIRE WEATHER

After this upper low exits the area this evening, a much drier airmass arrives Friday into Saturday. Breezy offshore winds over the ridges will develop Thursday evening in Del Norte and Siskiyou tonight, and over much of the interior ridges Friday night. Lake County, especially, could see more widespread offshore winds over the higher terrain. Overnight recoveries outside the valley floors are likely to be poor given these offshore winds with Maximum RHs in the 20s and 30s. While critical conditions are possible, wetting rains today may limit the impact of these conditions somewhat. There is also some uncertainty on how long and how widespread these winds will be. This will need to be watched for potential fire weather headlines. JB

COASTAL FLOODING

High astronomical tides associated with the full moon will bring chances for coastal flooding around Humboldt Bay starting as early as Sunday with chances continuing through next week. Astronomical tides at the North Spit tide gauge reaches 7.49 ft MLLW on 11:26 AM Sunday. With the tidal anomaly currently running 1.0 to 1.5 ft above forecast, minor coastal flooding is possible at these levels. The highest astronomical tides, and highest chances for coastal flooding, are forecast to be on Tuesday and Wednesday of next week at 8.04 ft and 8.06 ft, respectively. JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 6 PM this evening to 9 PM PDT Friday for PZZ450-455.

Small Craft Advisory from 9 AM this morning to 6 PM PDT this evening for PZZ470.

Gale Warning from 6 PM this evening to 9 PM PDT Friday for PZZ470.

Small Craft Advisory from 9 AM this morning to 9 PM PDT this evening for PZZ475.

Gale Warning from 9 PM this evening to 9 PM PDT Friday for PZZ475.