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FXUS66 KSEW 231626

AFDSEW



Area Forecast Discussion

National Weather Service Seattle WA

926 AM PDT Tue Apr 23 2024



.UPDATE...Forecast on track this morning. Cross cascade gradient

has turned negative and reports from North Bend have east winds

gusting in the 15 to 25 mph range this morning. Low level flow

will not turn onshore for the interior until tonight allowing high

temperatures to rise into the mid 60s to lower 70s. Upper level

trough arriving Wednesday with cooler and wetter weather into the

weekend. Previous discussion below with update aviation and marine

sections. Felton



&&



.SYNOPSIS...High pressure will maintain mild and dry conditions 

across the region through Tuesday. From Wednesday through the end 

of the week, expect a series of disturbances to bring a return of 

clouds and precipitation with temperatures trending closer to 

seasonal normals. This pattern will remain through the start of 

next week with periodic round of mountain snow and lowland rain.



.SHORT TERM /TODAY THROUGH THURSDAY/...High pressure brings one

more dry and mild day to western WA today. Temperatures will track

a few degrees warmer in the interior with afternoon highs in the

upper 60s to lower 70s. The coast will see 60s too but winds will

be switching to cooler onshore flow this afternoon. 



Cooler, cloudier and wetter weather returns for Wednesday as an 

upper low tracks through B.C. (with a weak front draped over 

western WA). Most of the rainfall will be over the coast and

mountains with some rain shadowing in the central sound. A trough

moves inland on Thursday with more rain and cool weather (highs 

in the 50s). Rainfall will be more widespread with much of the

region seeing measurable amounts. 33



.LONG TERM /FRIDAY THROUGH MONDAY/...Troughing over the Pac NW

will keep western WA cool and showery moving into this weekend.

Temperatures will track below average with highs in the 50s. Lows

will be in the 40s. Then, looking further ahead, a deep upper low

will spin offshore as we move into next week. Temperatures

continue to dip below average and we may see lows in the mid to

upper 30s Monday night. Snow levels will lower to around 3000 ft

with a few inches of snow possible at the mountain highway passes.

33



.AVIATION...SW winds aloft as an upper-ridge axis shifts eastward

with troughing upstream. Widespread VFR conditions are expected 

through much of the upcoming TAF period. High clouds are pushing 

in ahead of the next disturbance entering later on Wednesday. 

Surface winds are on the lighter side or calm for many this 

morning but should begin to pick up in the afternoon out of the 

W/NW between 5- 10 kt as winds push through the Strait of Juan de 

Fuca and into the Puget Sound area. Winds will trend more out of 

the south on later overnight in response to the aforementioned 

system. 



.KSEA...VFR throughout the TAF period with high clouds. NNE winds

4 to 8 kt this morning becoming WNW 5 to 10 kt in the afternoon 

before a transition to southerly after around 12Z tomorrow 

morning. 



McMillian/LH



.MARINE...Thermal trough to our south with surface high pressure 

well offshore. Generally benign seas today aside from the Central 

and Eastern Strait of Juan de Fuca where a SCA is in place through 

the overnight. The next disturbance is on tap to arrive early 

Wednesday but won't pack much of a punch. But, the next system will 

arrive on Thursday. Winds will likely increase with this system but 

the exact details are still uncertain at this time. 



4 to 6 feet seas are in the forecast through much of the week.



McMillian/LH



.HYDROLOGY...No river flooding is expected through the next seven

days.



&&



.SEW WATCHES/WARNINGS/ADVISORIES...

WA...None.

PZ...Small Craft Advisory from 2 PM this afternoon to 6 AM PDT 

     Wednesday for Central U.S. Waters Strait Of Juan De Fuca-

     East Entrance U.S. Waters Strait Of Juan De Fuca.



&&



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