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Area forecast discussion...correction 
National Weather Service Portland or 
230 am PST Sat Nov 7 2009 


Corrected advisory section 


Synopsis...a cool showery air mass will continue to spread into the 
Pacific northwest today and early tonight as a couple of short waves 
move through in a westerly flow aloft. This will produce valley rain 
showers and mountain snow showers. The air mass will also continue to 
be a bit unstable especially near the coast. The upper flow will 
buckle as a frontal system develops off the coast Sunday...brushing 
the area with a weak warm front. The associated rather strong cold 
front will move through Monday and early Monday evening with more 
Rain...Mountain snow and brisk winds. 
&& 


Short term...a westerly flow aloft in the wake of the cold front 
that moved through southwest Washington and northwest Oregon Thursday 
night will continue today and into early tonight. One short wave in 
this flow came through overnight with some pretty good rain 
showers...and a few thunderstorms near the coast. One strong storm 
came through the North Lincoln city and Roads End area around 930 PM 
and apparently did some damage. This short wave will move mostly east 
of our area by sunrise. 


A second short wave is just now crossing 130w and will reach the 
coast this morning and push inland in the late morning and afternoon. 
This short wave will produce a good band of showers again. It should 
also be a bit unstable with this band...especially at the coast but 
possibly inland again as well. Shear profiles look similar to 
overnight...not a lot of directional shear but good speed shear...and 
thus the thunderstorms near the coast today could again be on the 
stronger side. This short wave does not appear to clear our forecast 
area until some time tonight...after which the showers should ease. 
As a result...the Winter Weather Advisory for the Cascades continues 
to look good into tonight as well. Snow levels will be around 3000 to 
3500 feet today and tonight. 


Winds will be a bit breezy at times with this short wave today... 
especially at the coast. In addition...winds will be gusty at times 
with the showers. 


The upper flow begins to buckle and back Sunday and Monday as the 
next frontal system develops off the coast. The models say some sort 
of warm advection precipitation may affect part of our area 
Sunday...then lift north Sunday night. The associated strong cold 
front will move in Monday and move east Monday night. This front 
should produce gales again along the coast with gusty winds along the 
coastal strip...and breezy conditions inland. Snow levels lift some 
ahead of this front...so we will have to see if they lower soon 
enough to get enough snow for another Winter Weather Advisory in the 
Cascades. Right now it is looking rather iffy. Tolleson 


Long term...no changes. Previous discussion follows...snow levels 
will start falling again Monday night as the next strong frontal 
system moves across the Cascades and the cool upper level trough 
moves in behind it. Showery weather with snow levels between 3000 
and 4000 feet will persist through Wednesday morning. Extended models 
are currently showing the upper level trough weakening out on 
Wednesday to be replace by a ridge on Thursday and Friday. If this 
trend holds true drier weather is possible for a couple of days. 
Ruthford. 
&& 


Aviation...mostly VFR today except...local MVFR ceilings/visibilities and 
small hail possible in afternoon showers and thunderstorms as weak 
front moves through. These showers/isolated thunderstorms should move southeast 
across the Willamette Valley between 20z-07z. 


Kpdx and approaches...mainly VFR...brief MVFR ceilings/visibilities possible in 
showers/isolated thunderstorms this afternoon and evening. 
&& 


Marine...main concern today will be the very large seas and high 
winds. Seas of 23-27 feet will impact the coastal waters through this 
afternoon...then very gradually subside tonight through early next 
week. A cold front this afternoon should bring brief gales today. 
Another good chance for gales with a stronger front anticipated Sun 
night/Mon. 
&& 


Pqr watches/warnings/advisories... 
WA/OR...Gale Warning from Cape Shoalwater to Florence today. 
High surf warning South Washington...north and central 
Oregon coast today. 
Small Craft Advisory for rough Columbia River bar in 
effect through Sunday. 
Winter Weather Advisory for snow for the South 
Washington and the north and central Oregon Cascades 
continues through 10 PM tonight. 


&& 


$$ 


More weather information online at... 
http://weather.Gov/Portland 




This discussion is for northwest Oregon and southwest Washington from 
the Cascade crest to 60 nautical miles offshore. The area is commonly 
referred to as the forecast area.