Marine Weather Net

Central U.S. Waters Strait of Juan de Fuca Marine Forecast


TODAY

LIGHT
WINDS

TONIGHT

W
WINDS
TO 10
KNOTS

MON

N
WINDS
TO 10
KNOTS

MON NIGHT

W
WINDS
15 - 25
KNOTS

The Marine Weather Forecast In Detail:
PZZ131 Forecast Issued: 852 AM PDT Sun Sep 25 2022

Today...Light Wind Becoming E To 10 Kt In The Afternoon. Wind Waves 1 Ft Or Less.
Tonight...W Wind To 10 Kt In The Evening Becoming Light. Wind Waves 1 Ft Or Less.
Mon...Light Wind Becoming N To 10 Kt In The Afternoon. Wind Waves 1 Ft Or Less.
Mon Night...W Wind 15 To 25 Kt. Wind Waves 2 To 4 Ft.
Tue...Light Wind. Wind Waves Less Than 1 Ft.
Tue Night...Nw Wind 15 To 25 Kt Becoming Sw To 10 Kt After Midnight. Wind Waves 2 To 4 Ft Subsiding To 1 Ft Or Less.
Wed...Light Wind Becoming Sw To 10 Kt. Wind Waves 1 Ft Or Less.
Thu...Light Wind. Wind Waves Less Than 1 Ft.
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Area Forecast Discussion
National Weather Service Seattle WA
953am PDT Sunday September 25 2022

Synopsis
An upper level ridge will remain over the region through at least Tuesday with warm and dry conditions expected to continue. Elevated fire weather concerns Monday as light offshore flow develops. The next disturbance approaches midweek, with the following frontal system bringing cooler and cloudier conditions along with renewed rain chances.

Short Term - Today through Tuesday
Mostly sunny skies this morning, with some patches of fog remaining in the river valleys and some mid level haze associated with area fires. Otherwise, a mild and pleasant Saturday with a light north breeze increasing a bit into the afternoon with high temperatures likely to reach the upper 70s inland (and even around 70 at the coast with light offshore flow developing. Remainder of the previous short term discussion follows below. 12

As the upper level ridge gradually moves through W WA, with the ridge axis not exiting the area until Sunday night/Monday morning, clear skies and dry conditions will be on tap for the entire area. An embedded upper low moves inland Monday, but with hardly any precipitation associated with the feature, impact on the area should be minimal. However, one impact looks to be some increase in instability over the area, especially the Cascades. With temps peaking on Monday, this combination of hot, dry conditions along with this instability may give rise to fire weather concerns. For details on this, please see the Fire Weather section below. Temps cool slightly Tuesday as W WA falls on the backside of the ridge and an upper level low starts to make its way over the coastal waters. This system will bring a return to coastal clouds Monday night and into Tuesday before spilling inland as early as Tuesday night.

As alluded to earlier, warm temps expected today with lowland locations seeing highs ranging from the mid 70s to around 80. Coastal locations and those closer to the water will be a bit cooler with highs in the mid to upper 60s. Temps bump up a couple of degrees Monday, again the warmest day of the short term forecast, with lowland highs generally ranging from the upper 70s to mid 80s. Locations near water will still be cooler, but still a couple of degrees warmer than today. Temps Tuesday look to fall just a bit, with highs on par with what is expected today. 18

Long Term - Wednesday Through Saturday
Models in general agreement on the two systems that are expected to move through the area on Wednesday and again on Saturday, although details do vary. The first system expected Wednesday has both models agreeing that the front will dissipate as the upper trough moves eastward. Currently the GFS (Global Forecast System) has more moisture coming into the area on the back side of the trough, allowing precipitation to linger into Thursday, however the ECMWF (European Centre for Medium-Range Weather Forecasts) seems less impressed and has this feature drier. Ensembles leaning more in the Euro direction and as such, Probability of Precipitation here generally ranging in the slight chance to low end chance for most locations, however the coast seems to get into solid chance /around 50 pct/ as the front first comes on shore Wednesday morning.

Models sync back up again late in the day Thursday with a shortwave ridge overhead, bringing dry conditions again for all of Friday and the start of Saturday. Right now, both deterministic models show the upper low associated with this second front looks to pull well north of the area and thus limiting moisture with said front. Ensembles reflect this as well with mean precipitation lower than what is expected Wed. The thing to watch here will be the general trough pattern that will persist over the coastal waters as the main upper low will continue to sit and churn, which may result in active weather for the first full week of October. 18

Marine
Northerly flow will prevail over the waters through Monday with high pressure situated offshore. An onshore push will develop Monday afternoon and evening with Small Craft Advisory winds likely along the central and eastern portions of the Strait of Juan de Fuca. A frontal system will cross the Coastal Waters Tuesday night then shift inland on Wednesday. Moderate onshore flow will follow on Thursday. The flow will then turn offshore again on Friday.

Seas across the coastal waters hovering at 4-6 ft this morning and subsiding to 2-4 ft later today. Seas then look to build to 10-12 ft near midweek. 33/14

Fire Weather
A ridge of high pressure will remain in place for the bulk of theNear Term - Rest Of Today Through Tonight
wing warm and dry conditions to persist over W WA. Surface low pressure over NW OR may allow for weak northeasterly flow to set up over the west slopes of the Cascades. While these winds likely will not reach speeds to warrant Red Flag conditions, they will help to contribute the lowering of RHs during this time period. Additionally, as mentioned in the Short Term section, during this time an upper low embedded within the exiting ridge will help create unstable conditions, with widespread Mid-Level Haines Index values of 6 expected. These two ingredients could couple to trigger Dry and Unstable Red Flag criteria. In an abundance of caution, due largely to two large incidents remaining within the CWA, will opt to send out a Fire Weather Watch for Fire Wx Zones 658 and 659 with the morning forecast package. Main time of concern looks to be from noon through 7pm PDT. Beyond that, RH values start to recover and some relief can be expected. Understand however that this situation is pretty borderline, as it is late in the season. However, recent RH forecasts have trended to be a touch too high. Future shifts will have to weigh these options when determining whether or not to upgrade. 18

Hydrology
The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed.

NOAA Seattle WA Office: Watches - Warnings - Advisories
WA...Fire Weather Watch from Monday afternoon through Monday evening for West Slopes of the Central Cascades Generally above 1500 Feet-West Slopes of the North Cascades Generally above 1500 Feet.

PZ...None.