Marine Weather and Tide Forecast for Manchester, CA

DISCUSSION
A broad upper-level ridging continue promoting quiet weather conditions over the West Coast through today. Latest satellite imagery depicts high level moisture around the periphery of the ridge, with a narrow area of cirrus spreading across the northern portion of the forecast area. An inside slider shortwave trough will approaches from the north tonight and move in on Friday. This will likely lead to a shallow moist air and high boundary layer humidity tonight as an associated surface frontal boundary moves in. The potential of low clouds and fog will increase along the Nort Coast and adjacent river valleys into Friday morning. Low temperature are forecast to be in the mid 30's to low 40's for the lower elevations, and mid to upper 40's over the higher terrain.

The transient shortwave trough will continue to drive southward on Friday, before evolve into a closed low over Northern/Central California Saturday into Sunday. This cold core aloft will promote exceptionally dry airmass across the forecast area this weekend, with no rain expected.

Surface ridging will quickly spring back up offshore on Friday, resulting in a tighter pressure gradient for coastal areas.
Northerly winds are forecast to increase over the coastal headlands and exposed ridges. Overall, this northerly wind surge does not look very strong with very minimal impacts except over the coastal waters and coastal headland where isolated gusts greater than 45 mph are possible (35-80% chance), especially over the exposed terrain in Cape Mendocino. Lower elevations along the coast most likely in the 20-30 mph range based on the NBM probabilistic guidance.

Winds will shift to E-NE across the interior Friday evening. Once the cold core aloft heads southward on Saturday, northeasterly winds are expected to ramp up over the higher terrain and over southern Lake county. Strong NE winds may mix down to Lake level into the day on Sunday. NBM probability of 24 hr max wind gusts greater than 40 mph indicates there is a 50-60% chance for lowest elevations as Clearlake and Middleton on Saturday.

Now the airmass does not look exceptionally cold for January. It will be exceptionally dry over the weekend into early next week and depending how quickly winds decouple, we will likely have cold weather impacts and freezing or subfreezing temps again.


EXTENDED DISCUSSION
Tuesday through Thursday...
A broad H5 high pressure will build in quickly back to the West Coast on Tuesday. Omega block is expected to persist over the area through mid next week, with generally light offshore and frigging mornings. Deterministic and ensemble clusters shows the high pressure weaken and shift mid to late next week while an upper level trough approaches the region. Although, models are in disagreement in timing and position of this system. The ensemble cluster Phase Space indicates the spread between the ensemble forecast (EPS, GEFS, GEPS) is significant, will little overlap between them at times. The 24hr QPF Difference from Multi-Model Mean indicate there is a 60% of the models with precipitation across the West Coast late next week.



AVIATION
VFR skies continued across the region today. However a weak, dry and cool front will move over the region tonight; increasing high clouds will be the result. But some model guidances are introducing the possibility of patchy fog in the morning at the coast. More significantly, northerly surface winds will be revving up over Del Norte and Humboldt counties Friday afternoon as the pressure gradient tightens. Above ground "N-NE east" winds will increase by late day also...and thus promote the slight possibility of LLWS at the coast. /TA



MARINE
MARINE...Northerly winds winds remain relatively light this afternoon, around 5 to 15 kt, while the strongest winds move well offshore. Another long period wave is filling in this afternoon, with models show it peaking around 5 ft at 15 seconds on Friday.

A more significant wind event is expected Friday and Saturday.
Northerly winds are expected to start increasing tonight and continue to strengthen through Friday. Gale Force gusts are likely by sunrise Friday morning around 50 to 60 NM off Pt St George. These are expected to quickly spread closer to the coast and farther south through the morning and into the afternoon. A burst of Gale Force gusts are expected to sweep across the inner waters from Pt. Saint George to Cape Mendocino Friday afternoon, and have issued a Gale Warning for the northern inners in response. These stronger winds on Friday and Saturday will add 10 to 15 ft steep waves to the sea state. The models are coming into better agreement that these winds and locally generated seas will diminish Sunday afternoon and evening. The Gale Warning for the outer waters and small craft advisory for the southern inner waters continue unchanged with the afternoon update.

Sunday winds are expected to remain in the 15 to 25 kt range and slowly diminish through the day with lighter winds expected next week. A small swell of 4 to 5 feet at 15 seconds is expected to linger as well, with seas then possibly dropping below 5 ft by midweek next week. TRN/TDJ



EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Gale Warning from 3 PM Friday to midnight PST Friday night for PZZ450.

Small Craft Advisory from 3 PM Friday to 7 PM PST Saturday for PZZ455.

Gale Warning from 9 AM Friday to 7 PM PST Saturday for PZZ470.

Gale Warning from 3 PM Friday to 7 PM PST Saturday for PZZ475.