textproduct: Eureka

SYNOPSIS

Gusty northerly winds continue through the evening, easing a bit by Tuesday. Cold temperatures are likely after the winds back off overnight, Tuesday and Wednesday morning.

DISCUSSION

As high pressure fills in behind the passing cold front, gusty winds out of the north have ramped up in its wake. This is due to a well mixed boundary layer, promoting efficient downward momentum transfer and gusty surface winds along the coast. Also, a cutoff low to the south tightens the pressure gradient against the building ridge. Gusts greater than 30mph have been recorded at the Crescent City airport and Cooskie Mountain as well as coastal headlands and the usual areas exposed on the coast and at elevation. Winds will ease some Tuesday, but will remain breezy through Tuesday afternoon while remaining elevated over the near and far coastal waters. Highlighted hazards for area waters are covered in the Marine section below.

Chilly, and potentially frosty, morning conditions could occur in the wake of the passing front Tuesday and Wednesday mornings. However, on Tuesday morning, lingering elevated winds along with generally overcast skies could result in morning temperatures above 36 resulting in no frost development. For both mornings, NBM indicates that coastal locations from about Albion in Mendocino County to the Oregon border have about a 60 to 80 percent chance of lows below 40 degrees (this includes areas around Humboldt Bay and Crescent City). There is also about a 50 to 70 percent chance for morning low temperatures 36 degrees or less for some regions of interior Del Norte, interior Humboldt, Trinity, and NE Mendocino counties. The growing season has begun for Mendocino, Lake, coastal Del Norte, and the northern Humboldt coast, so a frost product could be applicable for just NE Mendocino (including Legget, Laytonville, Willits, Potter Valley, and Covelo) for one or both mornings.

A strong Pacific ridge will generally remain in control as additional weak fronts attempt to briefly flatten it, introducing more very slim chances for light showers, mainly in Del Norte County. Chances for a wetting rainfall (0.1 inch or higher) only reach 25% to 35% late this week and increase some this coming weekend. There will be periods of rebounding high temperatures between the fronts. /JLW & JJW & EYS

AVIATION

MVFR conditions persist this morning with gusty northerlies along the coast. VFR is forecasted around 20Z (+/- 1hr) with >80% confidence. Strong winds to continue through the daylight and evening hours. Expected LLT as High-Resolution models suggest a speed maximum of 30-40kts at around 2500 ft AGL, especially closer to and south of Cape Mendocino. HREF and NAM models show a return of SCT-BKN ceilings this evening from 03Z-09Z. Strong winds could create hazy conditions at terminals near ocean shore break down to 4SM this afternoon. Inland terminals can expect valley fog clearing through the day with afternoon gusty winds mixing down to terminals. Wave clouds have been spotted on visual satellite, increasing the confidence in LLT near Terrain, especially by the King Range.

MARINE

Northerly winds are strengthening in all waters today due to a dry cold front that passed over the area yesterday. Northerly winds will be very strong as a sharp pressure gradient exists between Ukiah CA (1013mb) and Coos Bay OR (1023mb). Severe Gale conditions with gusts of 40 to 45 kts will remain in all zones before beginning to ease in the northern waters Tuesday morning and ease in the southern waters Wednesday early morning.

After these winds ease in the northern waters, it will take some time for the steep short period waves to dissipate. A small craft advisory will more likely than not be warranted through Tuesday after the winds have died below Gale Warning criteria. The southern waters can expect larger, steeper and more hazardous seas building 13 to 15 ft through Tuesday as local steep northerly waves mix with a NW swell of 9ft @ 13s. While these northerly winds ease greatly Wednesday, the typically windy spots near and downwind of Cape Mendocino will continue to blow at 15 to 20 kts through the rest of the week and likely longer. The aforementioned NW swell will decrease in size and will also remain through the week into the weekend.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Frost Advisory from 3 AM to 9 AM PDT Tuesday for CAZ101-103- 109>115.

NORTHWEST CALIFORNIA COASTAL WATERS... Gale Warning until 4 AM PDT Tuesday for PZZ450-470.

Gale Warning until 10 AM PDT Tuesday for PZZ455.

Gale Warning until 5 AM PDT Wednesday for PZZ475.