Marine Weather and Tide Forecast for Boulder Creek, CA

UPDATE
Issued at 815 PM PST Mon Jan 20 2025

First and foremost - change up to the ongoing headlines. The Wind Advisory for the North East Bay was cancelled early. The offshore gradient peaked earlier today and is currently on the downward trend. Winds are still breezy to gusty with 30-40 mph still being observed of the higher terrain, but not strong enough for the advisory.

Given the offshore flow this afternoon temperatures rose to above seasonal averages in a few spots. What a rebound from Sunday to Monday for max temps. Sonoma County Airport did set an un- official record high of 70 deg. The official climate site in Santa Rosa came up short at 68 deg missing the record by 2 degrees.
Offshore also wipe away the marine layer. No clouds and now marine layer lurking off the coast either. Therefore, clear skies expected tonight.

As the winds continue to weaken under clear skies temperatures become the next weather impact for the near term. No change with ongoing Frost ADvisory/Freeze Warnings. See below.

Key items we'll be focusing on for the upcoming week: cold overnights continue with even colder temperatures possible next weekend, winds ramp up once again late in the weekend, and low chance for precip to region next weekend.

MM

SHORT TERM
(This evening through Tuesday)
Issued at 144 PM PST Mon Jan 20 2025

Gusty winds have been observed across the Bay Area with peak gusts ranging from 66 mph to 72 mph. These winds have largely been concentrated over the interior North Bay Mountains where a Wind Advisory went into effect at 4 AM and will expire at 1 AM Tuesday.
Gusty winds have additionally been observed in the East Bay Hills where a few stations are hovering right around Wind Advisory criteria. A few sites (PG914 and PG696) in the vicinity of Mt.
Diablo State Park have been gusting to between 45 to 50 mph. With this in mind, a Wind Advisory has been issued beginning now through 1 AM Tuesday for the East Bay Hills with gusts between 35 to 50 mph possible. Diving deeper into our winds, the SFO-WMC pressure gradient was -12.40 hPa as of noon. This has weakened (slightly)
from earlier in the morning when the gradient was -12.70 hPa at 10 AM PST. WRF guidance shows the pressure gradient begins will begin to weaken more significantly during the late evening hours which should coincide with winds starting to weaken. There is some uncertainty on when the gradient will switch from negative (offshore) to positive (onshore). The WRF shows the switch happening early to mid morning on Tuesday whereas the HRRR and GFS models both show it happening later Tuesday morning. Regardless, as the pressure gradient weakens winds will gradually ease over the Bay Area and drop below Wind Advisory criteria by very early Tuesday morning.

Conditions are expected to remain clear overnight which brings us to our second hazard, a combination of Freeze Warnings and Frost Advisories. Frost Advisories have been issued for the interior Bay Area and Central Coast except for the southern Salinas Valley where a Freeze Warning has been issued instead. For the Frost Advisory, overnight temperatures are expected to drop as low as 33 degrees with particular emphasis on the Valleys and highest ridgelines.
Given the clear skies anticipated overnight, additional radiational cooling is expected to occur overnight which will push more locations across the CWA into Frost Advisory territory. A Freeze Warning will be in effect overnight for the southern Salinas Valley where temperatures will drop as low as 26 degrees. Portions of the Fort Hunter Liggett area and far southeastern Monterey County may see locally colder temperatures dropping as low as 29 degrees. These areas are bordering the Southern Salinas Valley and Arroyo Seco zone. Cold mornings will continue through the week ahead with high confidence in the additional issuance of Frost Advisories and medium confidence in the additional issuances of Freeze Warnings over the upcoming week.

LONG TERM
(Tuesday night through next Sunday)
Issued at 144 PM PST Mon Jan 20 2025

For those of you who would prefer slightly warmer daytime weather and less breezy conditions, the next week is for you! The positively tilted upper level trough that has been digging into the West Coast (bringing our early week wind) continues to look fairly progressive and is expected to move eastward, away from the West Coast, on Tuesday. In its place a ridge of high pressure will build over the West Coast and bring with it clear skies and a gradual warming trend through the week ahead. Daytime temperatures will generally be in the 60s while the warmest portions of southern Monterey county may reach the low 70s. On the flip side, clear skies overnight will lead to additional radiational cooling and will continue to necessitate the issuance of Frost/Freeze products across the Bay Area and Central Coast. The most likely locations will be in the North Bay Valleys and the interior Central Coast.

The pattern will again change late week as an upper level low slides into the western United States and deepens over CA, with the ECMWF showing the upper level low becoming cut-off over the Bay Area before moving southwards. While this system continues to trend fairly dry, it does look as though it will produce strong, gusty winds both over the marine environment and over the interior North Bay Mountains and East Bay Hills. High end small craft warnings are likely over the southern coastal waters while Gale Warnings are likely over the northern coastal waters. The NBM continues to show PoPs in the range of 30-40% along the Central Coast and lower PoP values across the Bay Area. If any rain does develop with this system, it is likely to be only drizzle directly along the coastline with particular emphasis on coastal Monterey County. Any rainfall that does accumulate on the Central Coast is likely to be less than a tenth of an inch, not meeting wetting rain criteria. CPC guidance highlights the weeks 3-4 outlook (February 1 - 14th) as when the return of above average precipitation is likely.

AVIATION
(06Z TAFS)
Issued at 831 PM PST Mon Jan 20 2025

Satellite continues to show clear skies across the terminals.
Therefore, high confidence that VFR will prevail through the TAF period as the offshore winds will continue to bring dry conditions.
Light offshore winds through the TAF period for most terminals.
Winds will turn N/NW by Tuesday afternoon.

Vicinity of SFO...VFR through the TAF period. Light winds overnight, with light to moderate NW winds by Tuesday afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Moderate SE drainage expected overnight. Winds turn NW by Tuesday afternoon.

MARINE
(Tonight through next Sunday)
Issued at 831 PM PST Mon Jan 20 2025

Offshore breeze across the waters through Tuesday, with moderate to strong breezes within the San Pablo and San Francisco Bays through early Tuesday morning. Winds calm after Tuesday through Thursday. Moderate seas will persist through Thursday with significant wave heights becoming rough by Friday. Possible gale force winds are expected Friday and into the weekend.

MTR WATCHES/WARNINGS/ADVISORIES
CA...Frost Advisory from 1 AM to 9 AM PST Tuesday for CAZ504-506-510- 513>515-517-518-528.

Freeze Warning from 1 AM to 9 AM PST Tuesday for CAZ516.

PZ...None.