textproduct: Eureka

SYNOPSIS

Gusty north winds during the afternoon will be the highlight of the forecast through the weekend with otherwise mild and sunny conditions. Winds will weaken with hotter conditions building through the week.

KEY MESSAGES

-Strong north winds will continue for one more day Sunday into Monday with peak gusts near 40 mph.

-Generally clear skies and dry conditions even along shore through early next week.

-Conditions will begin to warm again Sunday through most of next week.

DISCUSSION

A strong ridge of high pressure has begun to peak today over the eastern Pacific. Contrasting with a trough over the western US, this has form a strong pressure gradient parallel to shore. Persistent strong winds have built across the the interior and along shore with some isolated gusts near 40 mph. Though stubbornly consistent gusts have stayed below advisory criteria with limited potential for impacts or damage. The wind has pulled marine influence far inland and keep low levels well mixed, generally limiting high temperatures to the mid 60s and 70s. Coastal conditions have remained cool despite winds keeping skies mostly clear. Clear skies and drier air tonight might allow for some cooler overnight conditions, but winds will most likely remain to high to allow for any frost formation.

High pressure will begin to push inland Sunday and into early next week. The strongest North winds will shift towards the Sacramento Valley in response while winds will remain breezy near shore on Sunday, the strongest winds will shift to Lake County with gusts over 40 mph at high elevations and along the rim of the Sacramento Valley. At the same time, north winds Sunday will pull more air from the interior, promoting very dry conditions, especially far form the coast. Coastal conditions will remain mostly clear and dry

Winds will begin to weaken Monday through mid week as high pressure settles further onshore and weakens. Conditions will remain very dry with interior highs gradually approaching the 90s by Thursday. Any HeatRisk currently minor at most. A building inversion and weaker winds will likely allow a very shallow and weak marine layer to begin reforming onshore, though offshore flow overnight will generally limit the extent of any stratus and allow it to clear during the day. Some moderate north wind will remain close to shore but be much weaker for the interior.

Models diverge on the pattern late next week. Most models show a trough of some description moving over the Pacific around next weekend with a cutoff low off the central California coast, though the relative strength of either is uncertain. Cooler temperatures are near certain, but moisture is highly uncertain. About 25% of ensemble members show some rain showers and thunderstorms but the rest remain dry.

AVIATION

Prevailing VFR conditions are expected at all terminals during the next 24 hours. Breezy surface NW winds around 15-25 kts with gusts 25-35 kts through this evening, diminishing to 5-15 kts after 17/06Z. However, breezy conditions is expected to persist at CEC through the forecast period. In addition, low level wind shear (LLWS) around 30-35 kts at 1000-2000 feet is expected for KACV and KUKI between 6Z and 15Z with light to gentle winds at the surface. North-nortwest winds are expected to increase again by Sunday afternoon. /ZVS

MARINE

Northerly winds continue to increase this weekend across the waters as the pressure gradient tighten, peaking on Sunday afternoon. Gale force gusts around 34-45 kts expected across all zones, with the strongest winds downwind of Cape Mendocino. A Gale Warning is now in effect for all coastal zones. Steep to very steep, hazardous seas will continue to build with the increasing winds, peaking to 11-17 feet on Sunday.

By Monday, the pressure gradient relax slightly and the strongest winds moves offshore. However, conditions will remain hazardous across the waters for much of the workweek with strong to gale force gusts winds and steep to very steep seas./ZVS

FIRE WEATHER

Strong north winds have built all across the area today. Though most gusts have remained below 40 mph, sustained winds have been stubbornly consistent above 15 mph in exposed and wind channeled areas. Marine influence and mixing have so far kept conditions moderate with highs only near 70 and RH generally over 30 percent.

High pressure will shift more onshore by Sunday. Strong afternoon winds will continue, but the focus of stronger winds will shift closer to the rim of the Sacramento Valley, especially in Lake County. Winds will pull in drier air by Sunday, supporting very dry afternoon conditions in eastern Mendocino, Trinity, and Lake Counties with minimum RH near 15 percent. Overnight RH recovery will continue to worsen with upper elevation recoveries very poor by Monday morning. Winds will begin to weaken early week but very dry conditions will remain with increasing day time temperatures.

All that said, fuels generally retain a spring character. Although ERC values are forecast to jump up near record values for May, grasses remain mostly green for all locations but some of the hottest valleys in Lake and Mendocino Counties. Heavier fuels are retaining moderate moisture. Despite critical weather variables, fuels are very unlikely to support extreme fire at this time, hence a Red Flag Warning is not currently expected for these conditions in Lake, Trinity, or Mendocino Counties. This event, however, will likely push fuel towards a drier and more conducive state for fire in the coming weeks. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Gale Warning until 3 AM PDT Monday for PZZ450-455.

Gale Warning until 10 PM PDT Monday for PZZ470-475.