textproduct: Eureka

SYNOPSIS

Drying and stable weather is expected through most of the week with above normal high temperatures and chilly nights.

DISCUSSION

A dry, cold air mass is moving into the area this afternoon in the wake of a quick, progressive cold front exiting to the east- southeast. This pattern will result in gradually clearing skies throughout the evening.

High pressure aloft will build into the West Coast tonight into Monday. A Rex Block pattern will begin to unfold, with a major 500mb height anomaly setting up over the region on Tuesday, resulting in multiple days of dry and stable weather along warmer temperatures. This will allow dry east-northeasterly winds developing across the area. Moderate breezes are forecast to develop over the higher terrain across the interior late tonight through Monday morning. Areas of low clouds and fog are expected to develop across the interior valleys tonight into Monday morning. Overnight low temperatures are forecast to be in the chilly side with freezing minimums highly probable for valleys in Trinity and perhaps portions of interior Humboldt, interior Mendocino and Lake counties Monday morning.

Dry offshore flow (easterly winds), especially at night, will keep the air very dry and reinforce the warming trend by mid week. Highs are forecast to warm up into the lower to mid 70's in the interior next week. South-facing exposures and higher terrain stand the best chance for highs in the 70's, while valleys trapped under the nocturnal inversion with night and morning fog may not warm up even into the lower 60s, especially in Trinity and northern interior Humboldt. Even the coastal areas are expected to warm up to mid 60s to low 70's before the sea breezes develop, especially on Wednesday.

Global Ensembles and deterministic model guidances are suggesting a break- through in the westerlies or undercutting of the blocking ridge Thursday night into Friday. The forecast becomes more uncertain on Saturday, as some model guidance suggests dry weather will continue while other guidance suggests precipitation will return to the area. There is currently a 25-50% chance of rain will return as early as late Saturday, and a 40-70% chance rain will return as early as Sunday. Stand by for more details as the situation develops. /ZVS

AVIATION

In general, clearer skies and VFR conditions are expected this afternoon and evening as drier air fills in behind the front that moved through the region earlier this morning. Late tonight and into Monday morning, light ground fog could bring some IFR conditions for interior river valleys. Low clouds could also affect KUKI tonight and into tomorrow morning, as well. There is some potential for MVFR conditions for coastal terminals tonight. Clearing is forecast to occur later tomorrow morning for most terminals.

MARINE

Combined seas are currently right around 10 feet and will continue to build through the day as a long period westerly swell builds in. This swell will bring steep seas from 10 to almost 13 feet by late this evening and through the day Monday before subsiding around midweek. There is moderate confidence in at least a 24 hour period of calmer seas around midweek, but another set of swells are likely to steepen the seas again late in the week. Wind, however, will remain gentle.

BEACH HAZARDS

A long period westerly swell train continues through today with heights eventually building between 10 and 13 feet with periods near 16 seconds. This swell may be too large for sneaker waves, though it could still pose a threat to beachgoers. Breakers up to 16 feet for west and northwest facing beaches are forecast based on average beach slope profiles. Beachgoers venturing near or in the surf zone tonight or early Monday morning should remain vigilant. Avoid rocks, jetties and steep beaches.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Coastal Flood Advisory until noon PST today for CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 4 PM PST Monday for PZZ450-455- 470-475.