Marine Weather Net

James Island to Point Grenville WA out 10 NM Marine Forecast


TONIGHT

SE
WINDS
5 - 15
KNOTS

MON

S
WINDS
20 - 30
KNOTS

MON NIGHT

S
WINDS
15 - 25
KNOTS

TUE

S
WINDS
5 - 15
KNOTS

The Marine Weather Forecast In Detail:
PZZ153 Forecast Issued: 836 PM PST Sun Dec 05 2021

SMALL CRAFT ADVISORY IN EFFECT FROM 1 AM PST MONDAY THROUGH MONDAY EVENING
Tonight...Se Wind 5 To 15 Kt Rising To 20 To 30 Kt After Midnight. Wind Waves 1 To 2 Ft Building To 3 To 5 Ft After Midnight. Nw Swell 4 Ft At 8 Seconds. A Chance Of Rain In The Evening Then Rain Likely After Midnight.
Mon...S Wind 20 To 30 Kt Easing To 15 To 25 Kt In The Afternoon. Wind Waves 3 To 5 Ft Subsiding To 2 To 4 Ft In The Afternoon. Nw Swell 3 Ft At 9 Seconds Building To Sw At 10 Seconds In The Afternoon. Rain In The Morning Then A Chance Of Rain In The Afternoon.
Mon Night...S Wind 15 To 25 Kt Easing To 10 To 20 Kt After Midnight. Wind Waves 2 To 4 Ft Subsiding To 1 To 3 Ft After Midnight. Sw Swell 7 Ft At 10 Seconds. A Chance Of Rain In The Evening Then A Slight Chance Of Rain After Midnight.
Tue...S Wind 5 To 15 Kt. Wind Waves 1 To 2 Ft. Sw Swell 6 Ft At 11 Seconds.
Tue Night...W Wind 15 To 25 Kt Rising To 25 To 35 Kt After Midnight. Combined Seas 5 To 8 Ft With A Dominant Period Of 12 Seconds.
Wed...Nw Wind 25 To 35 Kt Easing To 20 To 30 Kt In The Afternoon. Combined Seas 4 To 7 Ft With A Dominant Period Of 10 Seconds.
Wed Night...Nw Wind 15 To 25 Kt. Wind Waves 2 To 4 Ft. W Swell 7 Ft At 11 Seconds.
Thu...Nw Wind 10 To 20 Kt Rising To 15 To 25 Kt. Wind Waves 1 To 3 Ft Building To 2 To 4 Ft. W Swell 15 Ft Subsiding To 13 Ft.
Fri...W Wind 10 To 20 Kt Becoming Sw 15 To 25 Kt. Wind Waves 1 To 3 Ft Building To 2 To 4 Ft. W Swell 11 Ft Subsiding To 9 Ft.
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836 PM PST Sun Dec 5 2021
Northern and Central Washington Coastal and Inland Waters - PZZ100
Another weather system will reach the waters late tonight and into Monday. Tuesday offers a brief break but another front Tuesday night and Wednesday will bring increased winds to most of the waters.
Area Forecast Discussion
National Weather Service Seattle WA
743pm PST Sunday Dec 5 2021

The forecast is on track tonight and no changes appear necessary.

The mid and upper levels this evening continue to feature very weak ridging that stems from an anticyclone centered off the CA Coast. Just upstream from this feature exists cyclonic flow over the GOA, with a shortwave set to dart across southern BC overnight and into Monday morning. The surface pattern is still dominated by high pressure, with a frontal system/cyclone noted off the BC Coast associated with the shortwave headed towards southern BC. This feature is likely to stall and weaken around Haida Gwaii through tomorrow.

Recent radar imagery is picking up some echoes over the area this evening, however 00z UIL sounding shows a very dry layer between about 800-700mb that will take a while to overcome. Near the surface, however, temperatures are in the upper 30s to around 40, with dewpoints very similar, making for early development of some fog via negligible dewpoint depressions. Expect continued increasing clouds this evening, with areas of fog and perhaps a few sprinkles and flakes.

Biggest concern overnight and Monday morning will continue.nue to be lowland snow potential and snow across the Cascade passes. A few noticeable differences between this event and the last event Sat night are the lack of strong warm air advection at the onset combined with snow levels at 500ft or below for most locations east of the Olympics. This will likely yield a better chance for wintry precip at the beginning of the event. As the column finally saturates and wet bulbs a bit (likely after midnight), expect overnight temperatures to fall to the low to mid 30s. Given best predicted forecast for snow levels near the surface combined with coldest surface air, best shot for light accumulation still appears to be from southern Snohomish Co northward thru Whatcom Co, with Whatcom seeing the best chance for accumulations near an inch. Strong warm air advection by around 18z Monday morning will help change snow over to rain, with precipitation gradually tapering through the rest of the day. Remember to plan for wintry travel conditions over the Passes, especially Mon morning and afternoon.

Previous discussion follows with an updated aviation section.

/issued 255pm PST Sunday Dec 5 2021/

Synopsis
Colder conditions will continue.nue into the week with multiple systems making their way through the area. These will bring mostly lowland rain, mountain snow, and periods of breezy conditions. Wintry precipitation is possible in the lowlands at times this week, with minor accumulations possible. Confidence is increasing in active weather continuing into next weekend.

.Short Term - Tonight through Wednesday
Dry and partly cloudy conditions will give way later tonight to additional precipitation as another system moves into the region. Given a moist boundary layer and wet ground from recent rainfall, expect patchy fog to develop tonight, especially in Lewis and Thurston Counties ahead of precipitation onset tonight.

With cold air in place, there will likely be period of a lowland wintry mix across the region late tonight through tomorrow morning, with a chance for light snow across portions of Whatcom and Skagit Counties. Snow-levels will be down to the surface here, with HREF guidance favoring more concentrated areas of precipitation here around daybreak on Monday. Expect snowfall to be heaviest at this time, with some portions of Whatcom and northern Skagit Counties seeing higher probabilities of at least 0.5 to 1" of snowfall accumulation through Monday morning. Accumulations will be most likely on grassy and elevated surfaces, with some potential of sticking on lesser traveled roadways in these areas. Further south into Snohomish County, a dusting of snow on grassy and elevated surfaces will be possible, with minimal impacts expected. While conditions will be favorable to see a rain snow mix across most of Western Washington's lowlands, HREF guidance is indicating the potential of shadowing to occur across portions of King and southern Snohomish Counties tomorrow morning. As for mountain pass snow, totals look much less than previously forecast, with a general 3 to 6 inches possible from late tonight through Tuesday morning. Those with travel interest across the passes should use caution and prepare for wintry driving conditions at times.

Snow levels will quickly rise from south to north through Monday morning, with precipitation changing over to all rain by the afternoon hours. Rainfall will gradually taper Monday evening, with only a few showers lingering into the overnight hours. While cloudy skies will likely persist through this period, areas of fog will again be possible across portions of the region late Monday night into Tuesday morning. Drier conditions expected on Tuesday with temperatures warming into the upper 40s in the lowlands with the passage of a weak E-W oriented shortwave ridge axis.

The next impactful system will approach Western Washington Tuesday night into Wednesday morning, bringing a return of lowland, mountain snow and breezy to gusty southwesterly winds. Winds will increase Tuesday night, with occasional gusts in the 25-35 mph range at times through Wednesday morning. Winds will turn more westerly by late morning/early afternoon and will decrease in strength Wednesday evening. Precipitation will spread across the region late Tuesday night - early Wednesday morning. Snow levels will gradually lower through the night and through the day Wednesday with the passage of the front. This will spell light rainfall amounts for the lowlands and impactful snow in the passes - as snow levels will remain below pass level for the duration of this event. Snowfall accumulations on the order of 8-12 inches for the Cascade passes will be a possibility through the day Wednesday.

Long Term - Thursday Through Sunday
Broad trough will remain in place on Thursday with additional precipitation expected in the form of lowland rain and mountain snow, as snow levels remain between 1000-1500 feet. Northwesterly flow regime remains in place, so active weather will continue.nue into the weekend. Similar to what is forecast early this week, a shortwave ridge axis will cross the region on Friday, giving us a brief break in precipitation before the next system reaches the area by Saturday. Early indications is that this will be a prolonged wet system, with persistent rain in the lowlands and impactful snow in the Olympics and Cascades. Critically, snow levels look to generally remain 4000 feet or less across most of the region, which will keep rainfall rates manageable across the lowlands. Still quite a bit of time for details to play out, so stay tuned this week!

Marine
Next frontal system will star to move over coastal waters late tonight and spreading inland Wednesday. A small craft advisory for the coastal waters remains in effect for this system. Another front will arrive Tuesday night or Wednesday morning, with a slightly better chance of gales along with a stronger onshore push through the Strait of Juan de Fuca expected in its wake. Will wait for current set of headlines to expire before considering any advisories or watches for this second system. Meanwhile, seas expected to build back to 9 to 10 ft Monday, coupling with aforementioned SCA (Small Craft Advisory) nicely. A more significant swell will arrive toward midweek with seas building to 10 to 13 ft over the coastal waters.

18

Hydrology
No river flooding is expected in the next 7 days.

NOAA Seattle WA Office: Watches - Warnings - Advisories
WA...None. PZ...Small Craft Advisory from 1am to 10pm PST Monday for
Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-
Coastal Waters From Cape Flattery To James Island Out 10 Nm-
Coastal Waters From James Island To Point Grenville 10 To 60 Nm-
Coastal Waters From James Island To Point Grenville Out 10 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-
West Entrance USA Waters Strait Of Juan De Fuca.