703 
fxus66 kpqr 201535 
afdpqr 


Area forecast discussion 
National Weather Service Portland or 
832 am PDT Sat Mar 20 2010 


Synopsis...a sharp upper level ridge over the pacnw this morning 
will shift east of The Rockies by sun. Low level offshore will turn 
back onshore on today...ahead of an upper level trough that will 
move in for sun and Monday. High pressure is expected to return briefly 
around Tuesday...before another Pacific system moves through midweek. 


&& 


Short term...winds have turned southerly off the coast as surface 
low well to the west has shifted northward. A weak front will push on 
shore late this afternoon or early evening with onshore flow 
developing inland this afternoon. The main threat of precipitation 
comes with the upper trough Sunday bringing lower snow levels and 
some orographic showers. The upper trough does not completely move 
through till Monday per NAM and GFS. 


With slowly approaching front. Another warm day is on tap over the 
County Warning Area...mainly the interior. Sunset 


Long term...no changes. Previous discussion unchanged... 
an upper level ridge will rebuild along the coast Tuesday...for a 
temporary return to dry weather. The ridge will shift east across 
the forecast area Tuesday/Tuesday night allowing the next Pacific weather 
system to approach the coast Wednesday. Rain will spread across the 
County Warning Area Wednesday. Unsettled conditions are possible through the end of the 
week. 


&& 


Aviation...dry offshore flow giving VFR conditions. Offshore flow 
weakens after 18z...with light southerly flow developing along the 
coast. This will allow low stratus and possibly fog to move up the 
Oregon coast after 20z. Expect ceilings to rise to MVFR on coast after 
02z. Inland...just middle and high clouds. Will have to wait until after 
02z to see lower VFR and MVFR clouds to increase inland. 


Kpdx and approaches...dry east winds with VFR conditions. However... 
winds turn more southerly between 20z and 22z as marine layer begins 
increasing over S Willamette Valley. 
&& 


Marine...high pressure inland moves little. However...low pressure over the 
NE Pacific will move NE towards British Columbia. Weak front will push 
onshore after 00z. Offshore flow weakens this am...with return to 
gusty S to southeast winds over the waters. Strongest winds will be over 
the outer waters. Seas slowly build...reaching 10 feet on sun. 
&& 


Pqr watches/warnings/advisories... 
or...none. 
Washington...none. 
Pz...Small Craft Advisory for winds through Sunday morning Cape 
Shoalwater to Florence. 


&& 


$$ 


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.