Marine Weather and Tide Forecast for Eureka, CA

DISCUSSION

.SHORT-TERM
Today through Friday
Coastal low clouds developed again over Humboldt Bay/Eel delta overnight. Low clouds and fog were also observed from satellite imagery extending into all North Coast river valleys early this morning. Some low clouds and possible fog also formed overnight in Mendocino coastal zones and adjacent river valleys. The stratus is forecast to quickly erode by mid to late morning with abundant sunshine across the forecast area today. Afternoon northerlies will continue to remain gusty along the land-ocean interface, particularly the coastal headlands and perhaps around Humboldt Bay in the late afternoon.

Interior temperatures are forecast to remain above normal today into Thursday. Warmest interior valleys are forecast to peak in the mid to upper 80's. A few hot spots such as Big Bar RAWS may hit 90-92F. High resolution models seem overdone with shower development this afternoon over the interior mountains. GFS and NAM soundings do indicate elevated CAPE profiles. GFS has much more stability and drying this afternoon while the NAM12 and other high resolution model simulations seem a bit overdone in this particular synoptic set up of a ridge building and drier NE flow aloft.

Warm, dry and stable weather to continue on Thursday. Stratus may start to bloom later tonight and then grow Thu-Thu night resulting in some minuscule drizzle drops by Fri morning. A 500mb trough will approach late on Friday. Instability increases and few late afternoon tstms will be possible over Trinity County. Legacy SREF and NBM indicate 15-20% chance of thunder late Friday afternoon and evening. At this point, main threat from these very short-lived storms with limited CAPE will be cloud-to-ground strikes.

.LONG-TERM...Saturday-Wednesday...A 500mb trough will traverse across the area on Saturday. The trough is expected to split with the southern branch of the split developing in a closed 500mb cyclonic circulation or cut-off low over southern CA by Sunday.
This will put much of the forecast in a dry northerly flow as a ridge builds toward the Pac NW by Sunday. There are not many members depicting wrap around precip swinging northward either. It will be unseasonably cooler with strong and blustery northwest to north winds this weekend. Rain and high mountain snow with isolated interior mountain tstms may linger on Saturday, but precipitation chances will approach zero or less than 10% on Sunday. N-NW winds will ramp up over the weekend and remain quite blustery with gusts in excess of 40-45 mph over the ridges and coastal headlands. If winds go calm, frost and subfreezing early morning temperatures are also possible for interior valleys, primarily for Trinity, northern Mendo and northern Lake, early Sunday morning. Chance for frost and freezing temps in these colder high mountain valleys diminish on Monday.

High temps in the interior will begin to rebound to around or slightly above seasonal averages (70s to lower 80's) early to mid next week. Coastal areas will most likely not warm up much at all with marine air influences each and every day. Ensemble means and deterministic global models continue to differ on how fast the closed low or cut-off low over the Desert SW ejects eastward. A narrow positive tilt 500mb ridge axis is forecast to lean over into the PAC NW early next week. This is dry synoptic pattern for NW California. Greater uncertainty arises with an upstream trough mid next week. This trough may end up digging well offshore, keeping the area in dry SW flow aloft. DB

AVIATION
Gusty northerly winds persisted at CEC overnight with gusts 15 to 25 knots. Marine stratus has been largely confined to the Humboldt coast south of Trinidad, producing IFR ceilings and reduced viz at ACV. Stratus is expected to dissipate late this morning as winds strengthen nearer to the coast beneath clear skies.
HRRR indicates the stratus layer returning to the coast by early Thursday morning as winds diminish overnight. Stratus will likely be more widespread bringing MVFR to IFR conditions to both coastal terminals.

MARINE
Northerly winds and steep wind waves will continue through Thursday. Conditions will begin to diminish Thursday afternoon as winds push further offshore. Small craft advisories will persist in the outer waters through Friday, becoming confined to the southern outer waters downwind of Cape Mendocino. A brief period of southerly winds is possible Friday as a weak cold front approaches the north coast, bringing a chance for light showers. Strong northerly winds will resume Friday night into Saturday as high pressure builds into the eastern Pacific. GFS model and 90th NBM are still forecasting sustained near gale to gale force winds and gusts exceeding 40 knots late Saturday into Sunday, peaking Sunday afternoon.

EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 11 AM PDT Thursday for PZZ450- 455.

Small Craft Advisory until 9 PM PDT Thursday for PZZ470.

Small Craft Advisory until 4 AM PDT Friday for PZZ475.