Marine Weather and Tide Forecast for Mount Shasta, CA

DISCUSSION

An H5 low centered over the Gulf of Alaska will maintain a broad area cyclonic flow over northern parts of the Pacific for the next several days. This will put the forecast area under southwesterly flow through Wednesday. For today, lingering light rainfall will slowly diminish this morning, and a break in activity is expected through tonight. By Monday morning, a warm front will approach the region before diminishing onshore. This front will allow for warm air advection and isentropic lift in the lower levels. This setup could allow for higher rainfall rates/amounts than what was seen Saturday into this morning. These rainfall chances will start to diminish through Monday evening. Again, little to no impacts are expected with these rainfall chances.

By Tuesday, heights aloft will increase, and temperatures will trend above normal both Tuesday and Wednesday. In fact, Wednesday looks to be the warmest day in the forecast. Not expecting any rainfall through this stretch.

By Thursday, models continue to depict an elongated trough developing over the Pacific just off the western CONUS. As it approaches the coast, a closed low develops on the southern extend as the flow splits off Friday. The result will be a larger broader area of cyclonic rotation over the Gulf of Alaska and a closed low over southern California. Uncertainty continues in the extended for Thursday onward as models are out of phase, so its still a little to early to say with much confidence some of the finer details. That said, we continue to see a signal for later parts of the week to experience more rainfall (potentially moderate to heavy) and strong winds. While there is the potential for higher elevation snowfall, it does not appear to be any significant accumulations at this time, but with the uncertainty this could change. Models continue to slow the advancement of the broad troughing over the Pacific over the western CONUS. Cluster analysis shows strong agreement of troughing over the PacNW late this week, but this has been the case for several days with the trough continually being delayed. This ultimately leads to little confidence in the extended. Stay tuned for more details on later parts of next week.

.AVIATION (12Z TAFs)...

Ceilings will be chaotic across the region as light rainfall continues for areas west of the Cascades. A combination of MVFR and VFR conditions are expected through much of this cycle with mostly VFR through much of today and early this evening. However, recent rainfall could lead to IFR/MFR conditions for westside valleys including KRBG and KMFR. Offshore flow may prevent low clouds from impacting the coast tonight. Lastly, there is some uncertainty for low clouds tonight impacting KLMT, but confidence was not high enough to include at this time even though some guidance is suggesting low level saturation. Can reevaluate in subsequent TAFs.

-Guerrero

MARINE
Updated 345 AM PST Sunday, November 8, 2026...Light rainfall will slowly diminish this morning. Winds will also continue to subside this morning, but high to very high long period westerly swell arrives this afternoon and continues through this evening resulting in warning level seas for all waters. Seas will likely peak around 16-20 feet at 16 seconds this afternoon/evening. Another front arrives on Monday which could bring gales to the northern waters with overall steep to very steep seas. Steep seas may continue through early parts of next week.

BEACH HAZARDS
Long period westerly swell will move into the coastal waters late tonight and Sunday morning, then peak at 16-20 feet at 16 seconds Sunday afternoon/evening. This will produce breaker heights in the surf zone of 22-27 feet. A High Surf Advisory is in effect through this evening.

Large breaking waves will create hazardous conditions along and within the surf zone, and could inundate beaches and low lying shorelines. Beach erosion is possible, and exposed infrastructure may be damaged.

MFR WATCHES/WARNINGS/ADVISORIES
OR...High Surf Advisory until 10 PM PST this evening for ORZ021-022.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 4 AM PST early this morning for PZZ350-356-370-376.

Hazardous Seas Warning until 10 PM PST this evening for PZZ350- 356-370-376.

Gale Warning until 4 AM PST early this morning for PZZ350-370.