Your Weather

To update your location please enter your ZIP code, city, state, airport code or country in the field below. Weather by E-mail: Forecast storm alerts. Weather E-Mail Alert Sign Up »

Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Tuesday
• 
• High: 76 °
• Low: 46 °
• T-Storms

• Wednesday
• 
• High: 63 °
• Low: 46 °
• Chance of T-Storms

• Thursday
• 
• High: 66 °
• Low: 48 °
• Chance of Rain

• Friday
• 
• High: 73 °
• Low: 48 °
• Mostly Cloudy

• Saturday
• 
• High: 79 °
• Low: 54 °
• Chance of Rain

Area forecast discussion 
National Weather Service Portland or 
834 PM PDT Monday Jun 17 2013 


Synopsis...an upper level low off the Pacific northwest coast was 
centered off the Oregon coast along 130w this evening...with a 
frontal band moving onto the coast and into the Coast Range this 
evening that will continue to weaken as it moves across southwest 
Washington and northwest Oregon overnight. The low will continue to 
drift toward the coast through Tuesday...producing more showers and 
thunderstorms especially Tuesday afternoon and evening. The low will 
finally move onshore late Tuesday night and Wednesday...continuing 
cool...unsettled and damp weather over the forecast area on 
Wednesday. The low slowly moves east into the northern rockies late 
in the week with a decrease in showers. A warmup is possible for the 
weekend as a weak upper level ridge builds into the Pacific 
northwest...but this appears to be temporary. 
&& 


Short term...this afternoon through Thursday...unsettled and cooler 
weather will be the rule the next few days as a slow moving upper 
level low drifts onshore and across the State of Oregon. 


The upper low is centered off the north Oregon coast along 130w this 
evening. It was pushing a frontal band onto the coast and into the 
Coast Range this evening. Some thunderstorms did develop out ahead 
of this band in the north Coast Range and west part of the Portland 
metropolitan area that moved north through southwest Washington on either 
side of Interstate 5. There were a couple of strong cells...one of 
which appeared to show a rotating updraft and moved a bit more 
eastward of most of the other cells. No reports of severe weather 
have been reported so far. 


The band will move across southwest Washington and northwest Oregon 
overnight with some showers. Believe the threat of thunder will ease 
overnight but will need to watch as we can get some nocturnal 
convection in this type of pattern at times. 


The low will continue to drift toward the coast Tuesday but the 
center will remain offshore. Nevertheless...expect more showers and 
possible thunderstorms on Tuesday...with the greatest coverage in the 
afternoon and evening. 


The low moves onshore late Tuesday night and across our forecast area 
on Wednesday for continued cloudy...cool...and unsettled conditions. 
Will likely see more showers and possibly a few thunderstorms again 
as well as the cool pool aloft moves through. Depending on the track 
of the low...a wraparound deformation zone could get into our 
northern zones around the northern periphery of the low...and if 
so...that area could have more steady stratiform type precipitation. 
The models have not been consistent with this yet so we will need to 
continue to watch for that. Tolleson 


Long term...no changes. Previous discussion follows... 
Thursday night through Monday...upper low over the Pacific northwest will slowly 
drift eastward Friday. By Saturday a weak ridge will be in place... 
for a return to dry and warm conditions. Uncertainty increases on 
Sunday...the models agree that a large low will carve out a longwave 
trough over the eastern Pacific. This low will send a very moist warm 
front and associated broad area of precipitation into the region. 
However...models disagree on timing with the GFS bringing the rain in 
on Sunday...while the European model (ecmwf) holds off until Monday. If the ecm 
solution holds...the area will potentially see the warmest 
temperatures of the year so far on Saturday. Burgess 
&& 


Aviation...variable middle and high clouds continue streaming over the 
region on SW flow aloft. Areas of MVFR conditions will continue along 
the coast tonight with primarily VFR across the interior. Onshore 
flow is a tad stronger tonight...but overall will have similar 
conditions Tuesday morning as we had this morning. Exception will be a 
bit more in the way of clouds from Salem southward. 


Kpdx and approaches...VFR conditions expected tonight through 
Tuesday. There is a 30 percent chance of MVFR ceilings between 10z 
and 17z Tuesday. 
&& 


Marine...a broad area of low pressure will continue to slowly track 
toward the coast through Wednesday. Winds generally 15 to 20 knots...but may 
have some gust up to 25 knots at times. 


Swell continues to be mixed...with primary swell from the west and 
secondary swell from the S. Overall...combined seas running 3 to 4 feet 
today...but as west swell increases up to 5 feet later tonight and 
Tuesday...the influence of S swell will decrease. 


Weak high pressure will build again over the NE Pacific later this week with 
a return of north to northwest winds...but still mostly 20 knots or less. 
&& 


Pqr watches/warnings/advisories... 
or...none. 
Washington...none. 
Pz...none. 
&& 


$$ 


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.