textproduct: Eureka

SYNOPSIS

Seasonably warm and dry conditions will build through midweek with gusty north wind along shore each afternoon.

DISCUSSION

Cooler than average temperatures persist behind a late season cold front that passed Friday. Clearing skies and the lingering colder air mass will bring chilly overnight lows, potentially down to near frost levels in the upper 30s for the colder interior valleys. Remnant moisture and the shorter duration of nighttime hours should limit or prevent frost formation however.

High pressure is strengthening over the easter Pacific. A Great Basin trough will enhance the local pressure gradient against the high, resulting in breezy to strong northerly winds. The focus of stronger will mainly be along the coastal areas and exposed interior areas. This pattern will remain relatively stuck, with afternoon gusts in excess of 30mph each day. The influence of high pressure will moderate interior temperatures to the mid to upper 80s for the warmer valleys starting Monday, but these values are still below average by 3-6 degrees.

The extended forecast holds the passing of a trough late next week, as early as Thursday. This will finally weaken the pressure gradient and ease the winds. Light showers or periods of drizzle will be possible the trough, but chances for meaningful rainfall are very low through Friday. Ensembles hare highlighted slightly high probabilities for far northeast Trinity County. If the modeled very weak elevated instability with the front passes through during peak heating, there may be a chance for a thunderstorm out there Thursday afternoon, but chances for that too are very low at this time.

AVIATION

Instability in a post-frontal air mass left VFR conditions with mostly terrain tied cumulus and strengthened northerly winds Friday evening. Soundings show a saturated level in the 1500 ft AGL level around Humboldt Bay overnight. There remains a 30% chance for ceilings to reach IFR levels around the bay and perhaps into ACV. If winds go calm some patchy fog will be possible after the recent rainfall. The expected light offshore winds should limit this threat, and anything that does manage to form will be quick to disperse Sunday morning as northerly winds quickly increase again. Gusts of 20-30 kts are forecast for the coastal terminals Sunday before winds ease again Sunday evening.

MARINE

Strong northerly winds are over the waters while steep seas build in response. Strengthening high pressure to the west will further strengthen winds throughout the day Sunday. Gale strength gusts will start in the southern waters Sunday morning before expanding northward through the afternoon. Gale Warnings remain over the outer waters, but gale conditions can be expected around Point St George and Cape Mendocino. The proximity of gale conditions to the inner zones will favor poorly modeled large to hazardous seas to pulse into the inner waters at times. The greatest threat for this will be over the late Monday, Tuesday, and Wednesday after maximum afternoon winds are achieved. A Hazardous Seas Watch or Warning may be required to cover this threat, though the period of hazardous level seas may be brief between these pulses.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM PDT Tuesday for PZZ450-455.

Small Craft Advisory until 3 PM PDT this afternoon for PZZ470.

Gale Warning from 3 PM this afternoon to 3 PM PDT Tuesday for PZZ470.

Small Craft Advisory until 9 AM PDT this morning for PZZ475.

Gale Warning from 9 AM this morning to 3 PM PDT Tuesday for PZZ475.