Alderpoint, CA 95511 Weather

Key messages

* Light to locally moderate rain likely today.

* Additional light rain possible Tuesday.

* Stronger storms with heavy rain possible starting late next week and into mid November.

Synopsis

A cold front will bring light to locally moderate rainfall with some possible isolated embedded thunderstorms today and tonight. Additional light rainfall is possible at times next week, with chances for heavier rainfall in the extended forecast.

Discussion

Rain chances increase Saturday morning as a NE Pacific trough moves in. Rainfall totals will be on the low side with the trough. The trough will turn negatively titled on approach and will contain some instability, so locally heavier rainfall amounts and perhaps some isolated thunderstorms are possible given the associated dynamics. Rainfall totals are forecast to be between a few hundredths to around 0.3 inches in localized areas. This cold trough will lower snow levels to around 5000 feet and may bring small accumulations near 1 inch over Scott Mountain pass.

A transient ridge will pass through Monday ahead of another trough, brining slightly warmer and drier conditions. Chances for light rainfall arrive Monday night into Tuesday. There is only a 30 to 40% chance for rainfall over 0.1 inch for the area with that trough. A deeper low with a stronger front is modeled for late next week. This could bring some higher rainfall amounts and round of gusty southerly winds, but it does look to weaken as it nears the N CA coast. Rainfall chances for over 1 inch are currently 25% for that system.

For the extended forecast, the longer term guidance continues to outline a stretch of more active weather and atmospheric river potential over week two, somewhere near or after November 9th. Models guidance can overestimate storm strength in the extended through the transition into the wet season, but the signal seems to be becoming more consistent and bears watching. JJW/JB

Aviation

(6Z TAFs): VFR conditions are likely early this morning at all the terminals as light offshore flow and a weak marine inversion prevent coastal stratus from forming. Some interior valley clouds and fog are possible, however. An approaching frontal system will bring light to locally moderate rain late morning and through the afternoon. Occasional MVFR ceilings and visibility reductions are possible during heavier rain showers. Rain moves out of the area Saturday evening and overnight. JB

Marine

Seas remain mild and are dominated by mid period swells as winds remain light. Tonight into Sunday northerly winds are expected to return again as high pressure builds in briefly. The most recent models are showing this to be fairly short lived and the northerly winds may not be very strong in the northern waters. Fairly light winds are expected on Monday with southerly winds returning as early as Tuesday.

Also of a note, a very long period northwest swell is expected to start moving into the waters Sunday late in the afternoon. Initial waves are expected to be around 2 feet at 21 seconds. This will likely bring some fairly big sets of larger waves interspersed with smaller waves overnight and into Monday. This may show up on the shoals near harbor entrances. MKK

Beach hazards

A very long period northwest swell arrives Sunday afternoon and into Monday. This will bring an extreme threat for sneaker waves as winds remain light and other wave groups remain limited. This swell starts at around 2 ft at 21 secs and builds to around 6 ft at 17 secs by Monday morning. A Beach Hazard Statement will be needed for this sneaker wave threat.

Sneaker waves are relatively large, unexpected waves with long period between large sets. Up to 30 minutes may pass between waves. Large, unexpected waves can sweep across the beach without warning, sweeping people into the sea from rocks, jetties, and beaches. Avoid jetties, steep beaches, and stay much farther back from the ocean!

Watches, warnings and advisories

CA: Beach Hazards Statement from Sunday evening through Monday evening for CAZ101-103-104-109.

NORTHWEST CALIFORNIA COASTAL WATERS: None.