865 
fxus66 kpqr 220331 
afdpqr 


Area forecast discussion 
National Weather Service Portland or 
830 PM PDT sun Mar 21 2010 


Synopsis...an upper trough and onshore flow will maintain showers 
into Monday. High pressure will take hold Tuesday and early 
Wednesday. A Pacific front will approach the region late Wednesday. 


&& 


Short term...satellite and radar show another line of showers moving 
across the Coast Range at 0330z...which will then push across the 
valleys and into the Cascades before midnight. This band appears 
associated with a shortwave moving onshore. Open cell cumulus follow 
this system...but not really impressive. So expect only scattered 
showers to continue overnight inland valleys...with better probability of precipitation 
continuing near the coast and elevated orographic terrain. The final 
vorticity maximum passes around middle day Monday in northwest flow out of the 
Gulf of Alaska...with any residual showers ending by later Monday afternoon 
or evening. Models in pretty good agreement on this pattern with the 
big upper ridge following Tuesday and Tuesday night. 


By late Wednesday another front and upper trough approach. This system 
appears to be becoming more negative tilt with time...so initially 
the stronger part of the system may go to the south of the County Warning Area. Rain shower 


Long term...the GFS and European model (ecmwf) are in general agreement through much 
of the week. Quick moving shortwaves rotate through the forecast 
area every 36 to 48 hours through the end of the week...bringing 
periods of precipitation and keeping temperatures near climatology. 
Brown 


&& 


Aviation...expect primarily VFR conditions tonight and Monday in 
slightly unstable onshore flow. A few areas of MVFR conditions will 
likely develop between 08z and 16z...with the greatest threat 
along the coast. High pressure will build over the area on Monday 
with decreasing showers. 


Kpdx and approaches...expect primarily VFR conditions tonight and 
Monday. There is a 30 percent chance of MVFR ceilings between 08z 
and 16z...especially near organized bands of showers. 


&& 


Marine...S to SW winds will remain well below small craft...with 
the next chance for small craft winds not until late Wednesday. Seas 
will remain below 10 feet over the next couple of days. 


&& 


Pqr watches/warnings/advisories... 
or...none. 
Washington...none. 
Pz...Small Craft Advisory for rough bar until midnight PDT tonight 
for Columbia River bar. 


Small Craft Advisory for rough bar from 8 am to 1 PM PDT Monday 
for Columbia River bar. 


&& 


$$ 


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.