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fxus66 ksew 052145 
afdsew 


Area forecast discussion 
National Weather Service Seattle Washington 
345 PM PDT Sat Jul 5 2008 


Synopsis...a weak front will swing through western Washington this 
evening...bringing scattered showers. Onshore flow will give a 
cloudy start to the day Sunday...with more sun in the afternoon. An 
upper ridge will build offshore early next week for mostly sunny and 
warmer days. A weak upper trough will approach the forecast area 
late in the week. 


&& 


Short term...front just reaching the coast at 21z. That would put 
it over Puget Sound sound 01z or so...but it is not strong at all and is 
barely hanging together in satellite imagery. Chance probability of precipitation seem about 
right this evening though most places will probably see a sprinkle. 


Models have been consistent about heights building tomorrow. Should 
be a warming trend beginning Sunday afternoon with highs Sunday in 
the low to middle 70s...cooler north and coast. More warming Monday 
under mostly sunny skies...will see some 80s Monday away from Puget Sound 
sound. Tuesday a similar story. With onshore flow there will be 
varying amounts of late night and morning marine stratus clouds but 
the afternoons and evenings will be sunny. There will not even be 
any stratus in the mountains and they will be warm each day. Burke 


Long term...warmth continues Wednesday and Thursday. Highs will 
push 80 away from the sound with 70s most other places. Onshore flow 
continues so local morning clouds and afternoon sun will be the 
rule. This is the classic western washingtons Summer pattern. 


Both the GFS and the Euro have a weak trough in the area Friday and 
Saturday. There is no precipitation with this trough but there is 
some depressing of heights. Would expect this to bring temperatures 
down a notch and also allow more clouds. Have indicated this in the 
grids and zones. Not particularly confident about this feature and 
have not hit it too hard. Burke 


&& 


Aviation...a weak cold front near the Washington coast will cross Puget Sound 
sound around 00z-01z then move over the Cascades and dissipate. Ceilings 
will lift some this evening behind the front...except for local MVFR 
ceilings around a convergence zone over the north Puget Sound sound. West flow 
aloft with low level onshore flow will continue late tonight and 
Sunday...with ceilings lowering back down to MVFR after 06z then 
improving after 18z Sunday. 


Ksea...still anticipating ceilings to lower back down to MVFR 22z-01z 
as the weak front crosses the area. Rain has been spotty/light so 
far which has allowed ceilings to improve for brief periods. This will 
probably continue but will hang on to the lower conditions since 
bkn016 still indicates sub 2000 feet ceilings are still possible. 
Improvement to VFR after 01z-02z still looks good. Convergence zone 
forming over north Puget Sound sound this evening should remain north of ksea. Kam 


&& 


Marine...the weak cold front near the coast will move over the 
Cascades and dissipate this evening. Winds coming down fast on the 
coast so have dropped the Small Craft Advisory there. Sca's for S winds over the 
interior have been generally marginal as expected...so will let them 
expire as planned at 5 PM. Post front westerly Small Craft Advisory in the Strait 
expected this evening. 


Another surface ridge forms about 300 nm offshore or along 130w by 
Sunday afternoon...so we will return to stronger onshore flow 
pattern that will likely last for the next week or longer. This 
episode of onshore flow will be more west-northwest which usually results in 
lower amounts of inland stratus...but it might turn more SW late in 
the week. Back to the Standard Summer afternoon/evening sca's in the 
Strait. 12z GFS showed 3.0 to 3.5 mb through the Strait Wednesday 
and Thursday evenings...so have made the stretch and indicated gale 
winds during those periods. Kam 


&& 


Sew watches/warnings/advisories... 
pz...Small Craft Advisory central and east Strait...northern inland 
waters...Admiralty Inlet...and Puget Sound sound/Hood Canal. 


$$ 


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