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Area forecast discussion 
National Weather Service Portland or 
833 am PDT sun Mar 14 2010 


Synopsis...high pressure will slowly move across the Pacific 
northwest today and Monday...holding a Pacific cold front just 
offshore. This will keep conditions mostly cloudy but mild through 
Monday. The front get close enough to the north coast to bring some 
light rain and sprinkles from time to time...and a warm front will 
bring a slight chance for rain inland Monday morning. Strong low 
pressure will develop along the front Monday...pushing the front 
onshore Monday night and Tuesday while the low moves into British 
Columbia. This will bring rain to much of the district Tuesday... 
followed by showery and cooler conditions Tuesday night and 
Wednesday. Strong high pressure will build across the region later in 
the week...likely resulting in several dry days. 


&& 


Short term...will need to leave in a little patchy fog this morning 
inland valleys as high clouds slow down the dissipation of fog. 
Otherwise frontal zone remains offshore...so just a minimal threat 
for a little light rain reaching the north coast later today. Will bump 
up temperatures lower elevations a degree or two for this afternoon as even 
with high clouds there should be good solar insolation today. 


Remainder of short term discussion unchanged... 
a warm front will lift north through the district Monday 
morning...possibly allowing some light rain or sprinkles further 
inland. Any lower level moisture should clear out for the 
afternoon...with even some breaks in the clouds likely later in the 
day. With the 06z GFS still suggesting widespread 850 mb temperatures around 
+8 degree c...any sunshine could push temperatures close to 70 degrees. 
Bumped the forecast temperatures for Monday upward a couple degrees...most 
inland valleys should reach 63-66 degrees. If it appears there will 
be more sunshine than currently forecast...later shifts may need to bump 
these temperatures up further. 


Models have been fairly consistent the past few runs in developing a 
strong surface low along the frontal zone Monday...the 06z GFS shows this 
low deepening to 987 mb near 43n/134w by 06z Tuesday...then racing toward 
the British Columbia coast Tuesday. This low will drive the frontal zone 
inland...meanwhile the high pressure over The Rockies will remain 
strong. As a result the front may linger over the district well into 
Tuesday evening...so expect rain Tuesday then slowly tapering off to 
showers Tuesday night. Snow levels will lower back down to around 
2000 to 3000 feet behind the front...possibly dusting the Cascades 
and higher Coast Range terrain with a couple inches of snow. A 
secondary disturbance may keep showers in the north into Wednesday 
along with cool temperatures. Weagle 


Long term...no changes. Previous discussion unchanged... 
showers will persist though Wednesday. GFS and European model (ecmwf) build a strong 
blocking ridge Thursday through Friday.GFS ensemble and the European model (ecmwf) 
give ME confidence that dry conditions will persist Thursday and 
Friday...and there is a good chance for dry conditions over most of 
the forecast area into the weekend. Schneider 


&& 


Aviation...mostly VFR conditions today as middle and high clouds 
continue to filter across the region. However...pockets of fog 
around keug and along the Columbia River will slowly burn out 
through 19z. Little change in overall pattern through tonight. 


Kpdx and approaches...VFR conditions are expected today and 
tonight...with mostly high clouds over region. 
&& 


Marine...weak high pressure inland...with persistent low pressure over the 
Gulf of Alaska. Slow moving front approaching the coast will bring near 
or above Small Craft Advisory winds over the outer waters. Have 
lowered advisory for the inner waters. Seas remain 9 to 11 feet...with 
heaviest on outer waters. Seas slowly rising tonight and Monday...with 
southerly gales likely as the cold front moves across region on Monday 
night and Tuesday. 
&& 


Pqr watches/warnings/advisories... 
or...none. 
Washington...none. 
Pz...Small Craft Advisory for winds through tonight for the outer coastal 
waters from 10 to 60 nm offshore. 


Small Craft Advisory for hazardous seas through tonight for the 
coastal waters out 60 nm. 


Small Craft Advisory for rough Columbia bar conditions through 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.