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Area forecast discussion 
National Weather Service Portland or 
231 PM PDT Sat Jul 05 2008 


Synopsis...a weak Pacific front near the coast this afternoon will 
move east of the region tonight...ending the threat of rain. High 
pressure will begin to rebuild over the area Sunday...then strengthen 
Monday through Wednesday of next week for warmer and dry weather. 
&& 


Short term...visible satellite and surface data show the front 
moving on the S Washington/north Oregon coast at 21z...while still a little off 
the central coast. Satellite and models suggest the front will hold 
together enough for some light rain over interior sections especially 
north as it moves inland for the remainder of the afternoon. By early 
evening an upper short wave providing some lift to the front will 
have moved off to the east...and the rain threat will have diminished to 
just some scattered showers. A slight chance of showers in upslope 
flow will continue near the Cascades later tonight and possibly into 
early sun...otherwise should be plenty of clouds leftover behind the 
front into sun. It does look like the clouds should break up from the 
S on sun based on the position of the surface ridge...but in the north it 
may take until later in the afternoon and evening. 


The upper ridge behind the front begins building on sun...then 
strengthens Monday. All areas are sunny by Monday afternoon after some 
morning clouds north coast and possibly up the Columbia River briefly 
in the morning. Maximum temperatures will rebound several degrees above 
normal Monday with further warming Tuesday...likely rising close to 90 again 
inland valleys as GFS and European model (ecmwf) show 850mb temperatures back up near 20c. Rain shower 


Long term...models show decent upper ridging continuing through middle 
week with temperatures near 90 likely in the inland areas. The GFS...European model (ecmwf) 
and Canadian show a short wave swinging through the Pacific northwest later in 
the week that should at least bring stronger onshore flow...cooler 
temperatures and increased clouds. Rain threat currently looks minimal as 
models show the main part of the system swinging inland across 
southern British Columbia/northern Washington. Models hint at short wave ridging returning 
by next Sat. Rain shower 
&& 


Aviation...frontal boundary now near the coastline...and will 
continue across the forecast area this evening. IFR ceilings along 
the coast will gradually give way to MVFR ceilings this evening...a mix 
of MVFR/VFR inland will continue ahead of the frontal passage...with 
possibly only slightly lifting behind the passage tonight. Light 
showers will continue with the front through this evening... 
especially over orographically favored higher terrain. Ceilings will 
continue overnight before lifting and clearing later Sunday as flow 
begins to turn more offshore in response to a building ridge. 


Kpdx and approaches...mainly VFR conditions continue tonight...with 
a brief return of MVFR ceilings Sunday morning before skies begin to 
clear later Sunday. Brown 
&& 


Marine...winds at buoys 29 and 89 would indicate the front has 
passed into the inner waters in the north and is steadily 
approaching the coastline. Winds will shift to the west behind the 
frontal passage and calm slightly...especially north. On Sunday...as 
an upper level ridge builds over the area...a thermal trough will 
begin to build up the California coast and bring small craft winds 
south of Cascade Head later Sunday and continue through middle week. 
Seas will also gradually build reaching around 9 feet later Sunday. A 
strong Ebb is expected Sun morning before ebbs begin to decrease. 
With relatively little swell do not expect hazardous conditions 
during the strong Ebb. 
&& 


Pqr watches/warnings/advisories... 
or/WA...Small Craft Advisory for winds Cascade Head to Florence 
Sunday afternoon through Monday evening. 
&& 


Preliminary point probability of precipitation (probability of measurable precipitation) 
AST 2-0000 pdx 410000 sle 310000 eug 310000 
$$ 


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.