textproduct: Eureka

KEY MESSAGES

* Another cold morning is expected Tuesday with areas of frost and freezing potential.

* Dry conditions will lead to areas of low relative humidities through the week.

* A warming trend is expected to impact the area through the week into the weekend, peaking on Friday.

SYNOPSIS

Clear skies and seasonable temperatures are expected today. Another chilly morning is forecast for Tuesday morning with areas of Frost and Freezing potential. A warming trend will increase temperatures through the week.

DISCUSSION

Last weekend, a cold front brought cooler and dry air to the area. This system disrupted the marine layer allowing for clear skies at the coast through early this week as steady light offshore winds overnight continue. Clear skies and light wind will allow for uninterrupted cooling in the valley floors. Frost Advisories and Freeze Warnings have already been issued for many interior valleys from 1 A.M. through 8 A.M. Tuesday morning. Wednesday night should be warm enough to have much less impacts from cooler temperatures as temperatures could struggle to reach or go below 32F.

Through the week, a slight warming trend will take effect due to a building upper level ridge. This weather pattern will result in calm, chilly conditions with building winds in the afternoon as daytime heating takes effect. Inland heating is likely to peak Thursday and Friday with valleys reaching the high 80s to low 90s again. Winds will be mostly terrain driven with upslope - upvalley flow. Relative Humidities will reach a minimum late week with widespread areas of RH values <20%. however, winds ware likely to remain terrain-driven and light to moderate late week.

This coming Sunday into next Monday, Ensemble clusters show an upper level trough and an associated cold front entering the area. Both the GEFS and EPS support this as well. This system is 7days out and could change substantially through the week. Most of this system's rain would fall in the northern counties of Del Norte, Humboldt, and Trinity where some of the highest ridges above 4000ft could see very light snow whereas Mendocino and Lake counties are more likely to see moderate to strong NW winds if this system remains on track. This system is capable of changing and updates can be expected through the week. DS

AVIATION...18Z UPDATE

VFR Conditions are expected to be widespread today for all terminals in NW CA. Gusty northerly winds are expected at coastal terminals and within river valleys near the coast. Inland terminals can expect terrain-driven upslope/upvalley winds, yet gusts are not expected to be widespread. Winds will calm near sunset with continued VFR ceilings through the night. Very shallow ground fog is possible, yet minimal impacts are expected at this time. DS

MARINE

Gale force winds have decreased through the morning leading to wave heights decreasing sooner than expected. Widespread small craft advisories remain as waves continue to be steep. A fairly sizable NW swell has also entered the waters which is currently being recorded at 7ft @ 17s. Moderate to fresh breezes are likely to develop leading to a continued lowering of short period seas and the overall sea state. This NW swell is likely to wane to 4-5ft and mix with a S swell of 3-4ft through the week. DS

FIRE WEATHER

Multiple days of cool but dry air has lowered ERC values. Much weaker, terrain-driven winds and an increasingly stable atmosphere in the coming days will help greatly reduce overall fire danger. However, dry conditions are expected through the week (around 20% RH each day) with worsening overnight recoveries through Thursday as midslope thermal belts develop. Smoke transport will also worsen through the week for any fires that do start. More moist air is expected to push across the area this weekend with a potential for very breezy conditions in Mendocino and Lake county late this weekend into early next week. DS

BEACH HAZARDS

A long period swell currently up to about 7 feet at 17 seconds will persist through the day Monday. As short period seas begin to fall, this swell will provide and increasing sneaker wave risk through the day. The swell will begin to decay Tuesday. The sneaker wave risk will lessen as the swell decays, but will remain through midweek especially as short period seas calm.

The highest risk is expected during periods of incoming tides. With high tides along the California coast at around 11am to 1pm. A positive tidal anomaly is yielding tides around 1-1.2 feet higher than predictions on top of higher than usual tides, adding to the threat. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... Beach Hazards Statement until 10 PM PDT this evening for CAZ101-103-104-109.

Frost Advisory from 1 AM to 8 AM PDT Tuesday for CAZ103-104- 106-108>111-114-116>118.

Freeze Warning from 1 AM to 8 AM PDT Tuesday for CAZ108-110- 111-114-116-117.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT Tuesday for PZZ450-455.

Small Craft Advisory until noon PDT Tuesday for PZZ470-475.