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Area forecast discussion 
National Weather Service Portland or 
900 PM PDT Monday Oct 06 2008 


Synopsis...a strong Pacific weather system will move inland tonight 
with another shot of wind to the coast and more substantial rain 
through late Tuesday. Westerly flow will dominate through middle week before 
expected drier conditions set in later in the week. 
&& 


Short term...radar imagery showing a fairly solid band of rain 
moving across the Coast Range this evening. The low level cold front 
is still well offshore and should make landfall by midnight and move 
east of the Cascades by early morning. Gusty winds will accompany and 
follow the front but will stay below warning levels as the main low 
center swings in further to the north. Rain will turn to showers 
behind the front on Tuesday as much cooler air invades from the Gulf of 
Alaska. In fact...by midday Tuesday snow levels may drop to near pass 
levels in the north Cascade zones. However...by this time most 
of the precipitation will be winding down so snow accumulation at the passes 
is not expected to be significant. Southern areas will dry out more 
quickly on Tuesday as the 850 mb flow turns northerly. 


Westerly flow with intermittent shortwaves passing by to the north 
should keep a slight chance of showers in the forecast across the 
northern zones and over higher elevations through Thursday. 


Long term...no changes. Previous discussion follows... 
improving weather conditions expected for the extended period. As the 
cold upper level trough swings to the east...a possible strong ridge 
builds in over the forecast area into the weekend. The intensity of 
the departing trough and incoming ridge are not agreed upon by the 
Middle-Range models so therefore have gone with a more middle of the 
Road solution. Should expect to see a drying trend by early weekend. 
Brown 
&& 


Aviation...except for some MVFR ceilings along the coast...conditions 
predominantly VFR this evening. Cold front expected to reach kast 
around 06z...and move through keug by 12z. Expect predominantly MVFR 
conditions with the front...although there is a small chance for 
some IFR conditions especially along the coast. Post frontal air mass 
expected to transition from high end MVFR to low end VFR ceilings Tuesday 
morning. 


Kpdx and approaches...VFR conditions past midnight...then clouds 
lowering to MVFR ceilings with the front. Frontal passage expected 
around 10z. MVFR ceilings expected immediately behind the 
front...improving to VFR Tuesday morning. 
&& 


Marine...winds over northern waters have already risen to gale 
force gusts...and expected to remain so until frontal passage around 
midnight. Initially strong westerly winds behind front...but high 
pressure builds in quickly Tuesday taking winds below small craft in the 
morning. With winds running stronger than models...not unexpectedly 
seas have built quicker than gww forecast. Overall though...gww wave 
heights Tuesday are probably not bad for the forecast area as local gale 
force winds will tend to be short lived....and biggest swell train 
offshore is directed to our north towards Vancouver Island. 
&& 


Pqr watches/warnings/advisories... 
or/WA...Small Craft Advisory for rough Columbia River bar 
9 PM tonight through early Tuesday morning. 
Gale Warning Cape Shoalwater to Cascade Head through 
midnight tonight. 
Small Craft Advisory for winds Cascade Head to 
Florence through early Tuesday morning. 
Small Craft Advisory for hazardous seas Cascade Head 
to Florence through Tuesday night. 
&& 


$$ 


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.