Weather

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fxus66 ksew 080348 
afdsew 


Area forecast discussion 
National Weather Service Seattle Washington 
845 PM PDT sun Sep 7 2008 


Synopsis...an upper level ridge combined with low level offshore 
flow will provide warm temperatures and mostly clear skies through 
Monday. A weak frontal system will pass through western Washington 
Monday night...turning the flow onshore and ushering in marine 
moisture. The ridge will build back in around 140w on Wednesday 
afternoon through Thursday for dry and warmer weather again. 


&& 


Short term...decent offshore flow this evening with mostly clear 
skies as the result. This pattern is expected to basically maintain 
itself through the 1st half of Monday with the thermally induced 
trough of low pressure at the surface remaining along the coast. 
This moderate offshore flow should also keep the fog/stratus to a 
minimum overnight...with only the most fog prone areas having any 
potential development overnight. 


The surface trough will shift inland midday...then east of the 
Cascades during the afternoon with onshore flow developing on its 
backside. At this point am expecting a nice warmup along the coast 
until early afternoon then the westerly winds will cool things off 
there. Over the interior...the onshore flow will kick in late enough 
in the day that it will go unnoticed and temperatures will be rather 
mild once again with mostly sunny skies. 


Overnight...marine push will continue with the main effect being 
somewhat cooler temperatures. All guidance hints at a relatively dry 
push...that is limited moisture for stratus formation...so it will 
likely be a mostly clear push with the exception of the coast where 
morning low clouds is a sure bet. Cerniglia 


Long term...from previous discussion...long range models are in 
good agreement...flow aloft turns westerly as the ridge flattens 
somewhat Thursday with another dissipating frontal system. Onshore 
flow follows Friday...and then ridge quickly amplifies Saturday as a 
thermal trough attempts to set up along the coast for another dry 
and warm weekend. Damico 


&& 


Aviation...a weakening upper level ridge over West Washington will move east 
Monday morning as a weak upper level trough and dissipating front 
approach the area. The remnants of the front will reach the coast 
Monday night. The air mass will remain dry and stable with residual 
dry northerly offshore flow allowing only isolated morning stratus 
and fog at best. 


Ksea...clear. Air mass is a little drier than last night. No stratus 
or fog expected Monday morning. North surface winds will continue 
through Monday. Kam 


&& 


Marine...observation and latest models indicate the Small Craft Advisory for the coastal 
waters isn't working out. Will drop it on the 9 PM package. 


B.C. Surface high is weakening and the surface trough along the 
Washington/Oregon coasts will shift east of the Cascades by Monday 
afternoon...as a weak upper level trough and dissipating front 
approach the area...and the big NE Pacific surface high becomes 
dominant. Westerly onshore gradients will be going up Monday 
afternoon...but latest models suggest that Small Craft Advisory winds in the Strait 
Monday afternoon may be too quick. Will re-evaluate this for the 3 
am package. Small Craft Advisory winds for the outer coastal waters may work out. West 
onshore flow continues for the most part for the rest of the week... 
but another upper level ridge Wednesday/Thursday may provide another 
really brief shot at offshore or just slack flow. Kam 


&& 


Sew watches/warnings/advisories... 
Washington...none. 
Pz...none. 


$$ 


Weather.Gov/Seattle