Sunrise 5:51 AM   Sunset 8:08 PM Moonrise 10:52 PM   Moonset 5:55 AM

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PZZ135 Puget Sound And Hood Canal- 246 Pm Pdt Fri Apr 26 2024
Tonight - NW wind 5 to 15 kt becoming sw after midnight. Wind waves 2 ft or less. Sat - S wind 10 to 20 kt. Wind waves 1 to 3 ft. Sat night - S wind 10 to 20 kt. Wind waves 1 to 3 ft. Sun - S wind 15 to 25 kt. Wind waves 2 to 4 ft. Sun night - SW wind 15 to 25 kt. Wind waves 2 to 4 ft. Mon - SW wind 15 to 25 kt easing to 10 to 20 kt in the afternoon. Wind waves 2 to 4 ft. Mon night - SW wind 15 to 25 kt becoming S to 10 kt after midnight. Wind waves 2 to 4 ft subsiding to 1 ft or less after midnight. Tue - S wind to 10 kt. Wind waves 1 ft or less. Wed - Light wind becoming N to 10 kt. Wind waves less than 1 ft becoming 1 ft or less.

PZZ100 246 Pm Pdt Fri Apr 26 2024
Synopsis for the northern and central washington coastal and inland waters - Surface low pressure continues to move inland with relatively benign conditions over the area waters. Another frontal system will move across area waters Saturday with elevated winds and seas. An active weather pattern will continue into the first part of next week. High pressure will build over the waters Tuesday night and Wednesday.

FXUS66 KPDT 270546 AFDPDT

Area Forecast Discussion National Weather Service Pendleton OR 1045 PM PDT Fri Apr 26 2024

.Updated Aviation Discussion.

UPDATE

Key Messages:

1. Thunderstorm threat waning tonight.

2. Breezy afternoon winds into the workweek, peaking on Monday.

Current radar and infrared satellite imagery showing spotty showers along the northern Blue Mountain foothills, Lower Columbia Basin, and Wallowa county under partly to mostly cloudy skies.
This is in response to the dropping upper level trough that is continuing into southern California, with a weak shortwave traveling across central Oregon. There have been only a couple cloud-to-cloud lightning strikes this evening, with activity continuing to taper off as the shortwave dissipates as it passes through the area. Spotty showers will still be possible along the Blue Mountains and Elkhorns overnight before tapering off through the early morning hours on Saturday. Rain chances (20-40%) will return along the Cascades and northern Blue Mountains Saturday afternoon as another shortwave passes through the Pacific Northwest.

The next weather concern resides with breezy afternoon winds over the next several days, associated with an upper level shortwave on Saturday, an approaching upper level low off the coast of British Columbia on Sunday, and a robust shortwave spinning off the parent low on Monday. These synoptic features will attribute to a pressure gradient setting up along the Cascades to produce wind gusts between 25-35 mph out of the west Saturday across the Simcoe Highlands, northern Blue Mountain foothills, Lower Columbia Basin, and Kittitas/Yakima Valleys. This will again occur across the same areas on Sunday, with gusts of 30-40 mph, and again on Monday as gusts approach Advisory levels. Confidence in these wind values is moderate (60-70%) as the GFS, NAM, and SREF all highlight pressure gradients between Portland and Spokane of 6-8 mb both Saturday and Sunday, increasing to 8-10 mb on Monday. 75



AVIATION
06Z TAFS
VFR conditions currently at all sites, which will stay the course through the period. Breezy winds between 10- 15kts are still occurring across most sites, which will linger overnight. The only exceptions are KBDN/KYKM, which are below 6 kts and will persist into early Saturday afternoon. Winds will stay elevated at all other sites overnight and increase to between 20- 25kts as ceilings drop to around OVC050 through the afternoon and evening. KPSC will be the outlier and should stay OVC100 through the afternoon before improving to BKN250 during the early evening. 75

PREV DISCUSSION... /issued 303 PM PDT Fri Apr 26 2024/

SHORT TERM
Today through Sunday
Current radar is showing a few showers popping up over the Ochoco-John Day Highlands and along portions of the Northern Blues and Wallowas. Observations over the last our shows that a few locations along the east slopes of the Cascades have received 0.01- 0.05 inches of precipitation.
Portions of the Ochoco-John Day Highlands have seen 0.02-0.04 inches and the Wallowas have seen around 0.06 inches so far.
Current satellite shows scattered clouds across the Basin and adjacent valleys as well as along the eastern mountains with embedded showers. Temperatures today will remain seasonal with the lower elevations seeing temperatures in the mid to high 60s, mid elevations seeing the mid to upper 50s and the highest elevations in the low to mid 40s.

Today the models remain in form agreement with the upper level low being mostly overhead and essentially straddling the region with the center of the low a bit to the south east. With he cold core to the southeast and upper level winds mostly southwesterly, orographic lift could help initiate some pulse thunderstorms over the eastern mountains. CAMs models show MUCAPE values to continue to be in the 250-350 J/kg with a few areas in Grant County showing values above 500 J/kg range with lapse rate around 7.2-7.4 C/km and effective bulk shear only in the 15-20 knot range. While some of these needed ingredients are weak, there is still a enough of them to put out a marginal possibility of 20-30% probabilities isolated thunderstorms could pop up along the eastern m mountains with the CAMs models and ensembles targeting Grant County with the highest probabilities, again only 20-30%. EFI shows the CWA to be under seasonable conditions with 70%raw ensembles having the PDT area in the low to mid 60s, 90% have the Basin and adjacent valleys in the mid to upper 60s with isolated 70s, mid elevations in the mid to upper 50s.

Models over the weekend remain in firm agreement with the upper level low moving off towards the southwest while another upper level trough begins to meander to the south out of the Gulf of Alaska. The region will shift into more of a westerly pattern and the concern over the weekend will lean more towards the winds. While the westerly flow will bring precipitation primarily to the mountains, the system will also usher in a bit cooler temperature along the Cascades bringing the snow levels a bit lower to around pass levels increasing the chances of some snowfall along Snoqualmie Pass by Sunday. Looking at the raw ensembles, 70-80% agree that there is near an inch of snowfall probable along the WA Cascade and 50-70% along the OR Cascades. Westerly flow will also cause an increase in the winds, especially through the Cascade Gaps. NBM ensembles show the 24 hour probability of max sustained winds of greater than 30 mph to be 60-90% probable through the Gorge, Columbia Basin, Simcoe Highlands, Yakima and Kittitas valleys and through Union County with some isolated pockets in central OR and along the eastern slopes.
EFI continues to show the temperatures over the weekend to be near seasonal averages with the ensembles showing the lower elevations in the mid to upper 60s, foothills in the upper 50s to low 60s, mid elevations in the low to mid 50s and the higher elevations in the low 40s. Bennese/90

LONG TERM...Monday 12Z(Monday) to Saturday 00Z(Friday)...

A upper-level trough pattern associated with a broad low moves southeasterly across BC coastline and then PacNW Monday into Tuesday night. As the trough passes eastward to The Rockies, PacNW begins entering a ridge Wednesday through the remainder of the forecast period (50-60% confidence).

Both deterministic models and ensemble means have a good agreement on the trough occurring Monday into Tuesday night, including the arrival of an upper ridge Wednesday into Friday. However, there is a uncertainty for Wednesday night with 21% total cluster members favoring a trough whereas 61% total members show a ridge occurring with the trough axis positioned in The Rockies. Thursday into Friday shows a decent agreement with ridge moving over PacNW. Chances of precip at the low elevations are low (<20%) with a 30-40% at the mountain areas for Monday morning into night as the broad low passes before precip starts to decrease when the ridge occurs. Gusty winds will occur between 20-35 kts for Monday into Tuesday as the broad low passes, influenced from the surface pressure gradient from the troughing. Snow levels from Monday to Tuesday will decrease to 2000- 4000 ft as the trough passes through, but increases to 3000-6000 ft with the ridge moving over PacNW enters between systems Wednesday into Friday. Feaster/97

PRELIMINARY POINT TEMPS/POPS
PDT 41 60 40 62 / 20 10 10 0 ALW 46 64 45 64 / 20 10 10 0 PSC 48 67 46 67 / 10 10 10 0 YKM 41 63 37 64 / 20 10 10 0 HRI 46 65 42 66 / 10 10 10 0 ELN 41 58 37 59 / 30 20 10 0 RDM 34 55 36 59 / 30 10 10 0 LGD 40 58 40 60 / 40 10 20 0 GCD 38 58 36 61 / 30 10 20 0 DLS 46 61 45 62 / 10 20 20 0

PDT WATCHES/WARNINGS/ADVISORIES
OR...None.
WA...None.

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Des Moines
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Fri -- 01:15 AM PDT     6.53 feet Low Tide
Fri -- 05:59 AM PDT     Sunrise
Fri -- 06:05 AM PDT     10.58 feet High Tide
Fri -- 06:59 AM PDT     Moonset
Fri -- 01:22 PM PDT     -1.32 feet Low Tide
Fri -- 08:14 PM PDT     Sunset
Fri -- 08:41 PM PDT     11.44 feet High Tide
Fri -- 11:57 PM PDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION

Des Moines, Washington, Tide feet

Duwamish Waterway
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Fri -- 01:18 AM PDT     6.14 feet Low Tide
Fri -- 05:59 AM PDT     Sunrise
Fri -- 06:01 AM PDT     9.97 feet High Tide
Fri -- 06:58 AM PDT     Moonset
Fri -- 01:25 PM PDT     -1.24 feet Low Tide
Fri -- 08:15 PM PDT     Sunset
Fri -- 08:37 PM PDT     10.78 feet High Tide
Fri -- 11:58 PM PDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION

Duwamish Waterway, Washington, Tide feet

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