Cape Shoalwater WA to Cape Lookout OR between 150 and 250 NM Offshore Forecast
|Today...S To Se Winds 10 To 20 Kt. Seas 7 To 12 Ft.|
|Tonight...E To Se Winds 10 To 20 Kt, Becoming E To Ne. Seas 6 To 9 Ft.|
|Wed...E To Se Winds 10 To 20 Kt, Becoming S. Seas 7 To 11 Ft.|
|Wed Night...S Winds 10 To 20 Kt. Seas 8 To 14 Ft. Chance Of Rain.|
|Thu...W To Nw Winds 5 To 15 Kt, Becoming S To Sw 10 To 20 Kt. Seas 12 To 14 Ft.|
|Thu Night...S Winds 5 To 15 Kt, Increasing To 15 To 25 Kt. Seas 9 To 11 Ft.|
|Fri...S Winds 15 To 25 Kt. Seas 8 To 12 Ft.|
|Fri Night...S Winds 15 To 25 Kt. Seas 8 To 12 Ft.|
|Sat...S Winds 20 To 30 Kt. Seas 7 To 12 Ft.|
|Sat Night...W To Nw Winds 10 To 20 Kt. Seas 8 To 11 Ft.|
| Area Forecast Discussion|
...UPDATED National Weather Service Portland OR
942am PST Tuesday Dec 1 2020
...Updated Aviation and Marine Sections
High pressure will dominant the weather through at least Thursday. This will result in mostly clear skies and near freezing morning temperatures. East winds will increase tonight and Wednesday, mainly though the Columbia Gorge and persist through the end of the week. The east winds will be strongest tonight and Wednesday. THe eat winds will reduce the threat for fog and stagnant air conditions for the northern areas, but lighter winds may result in stagnant air conditions and deteriorating air quality for the central and south Willamette Valley.
Today through Thursday night...Water vapor imagery shows a slightly positively-tilted upper level ridge over the Pacific NW early this morning. Near the surface, patchy fog has developed along the coast and in the interior valleys overnight. Oregon DOT web cameras and Airport ASOS's confirm that the fog is dense in areas withing the interior valleys, and have issued a dense fog advisory for this morning. Visibility reductions to around a quarter of a mile can be expected through mid morning.
The axis of the upper ridge will move over the area and inland this afternoon through Wednesday. This will be reflected at the surface as building high pressure east of the Cascades. Models are consistent with an inverted surface trough strengthening along the coast as the high pressure increases inland for strengthening east winds. The 0z NAM has been forecasting a -8 to -10 mb Troutdale to the Dalles surface pressure gradient tonight and Wednesday. This gradient is capable of producing strong gusty winds through the western Columbia Gorge with gusts of 45 mph possible for the east Portland and Vancouver metro areas near the gorge. Have issued a High Wind Advisory for the metro area for these expected localized strong winds. The wind gusts will be stronger for the Gorge where gusts of 70 to 80 mph is possible for the wind-favored areas like Crown Point.
Suspect the east winds will mostly be a gap flow event, but think the winds will be strong enough for the foothills and coast range to reduce the threat for stagnant air conditions. Have therefore scaled back the coverage of the air stagnation advisory. The winds have the best chance to be calm enough for stagnant air conditions in the central and south Willamette Valley tonight and Wednesday with stagnant conditions possibly expanding to the Lane County foothills and coast range on Thursday. East winds will persist through the Gorge Thursday, but not as strong as what is expected for on Wednesday. These winds should provide enough mixing to mitigate stagnant air conditions for the Portland and Vancouver metro area.
A weakening front will increase clouds Thursday and Thursday night, but do not expect any rain with it. ~TJ
No Changes. Previous discussion follows...Friday through Monday...There is some uncertainty in the extended as the aforementioned dying front has the ECMWF (European Centre for Medium-Range Weather Forecasts) chasing it with a largely dry cut off low forming and sliding across the region beginning Thursday night. It then meanders over the inland northwest through Monday. The remaining models simply bring the ridge back overhead with, maybe, another weak front Sunday.
Regardless, generally expect dry weather under cool conditions for the remainder of the week and weekend. areas of fog and/or frost will likely occur for most areas. Under a non-EC model solution, would also expect stagnant air to continue into early next week. /JBonk
No changes to current forecast. The wind will shift to an offshore pattern and persist through the end of the week. Latest models show a dying front moving through the waters Thu, which will allow the wind to veer SE to S. Wind gusts up to 25 kt are likely across the waters tonight into Wednesday. Gaps in the coastal terrain will be areas of stronger winds. Winds will stay below SCA (Small Craft Advisory) thresholds through the end of the week as high pressure resides over the Pacific NW. Seas will ramp up Wednesday night through Thursday as a long period northwest swell moves across the waters. Seas are likley to reach 13 ft, 17 sec early Thursday afternoon and fall below 10 ft by Friday morning. -BPhillips
.PQR WATCHES/WARNINGS/ADVISORIES... OR...Air Stagnation Advisory from 10pm this evening to 10am PST Saturday for Cascade Foothills in Lane County-Central Coast Range of Western Oregon-Central Columbia River Gorge- Central Oregon Coast-Central Willamette Valley-Coast Range of Northwest Oregon-Greater Portland Metro Area-Lower Columbia-Northern Oregon Cascade Foothills-South Willamette Valley-Upper Hood River Valley.
Dense Fog Advisory until noon PST today for Central Willamette Valley-Greater Portland Metro Area-Lower Columbia-South Willamette Valley.
Wind Advisory from 10pm this evening to 4pm PST Wednesday for Greater Portland Metro Area.
WA...Air Stagnation Advisory from 10pm this evening to 10am PST Saturday for Central Columbia River Gorge-I-5 Corridor in Cowlitz County-South Washington Cascade Foothills-Willapa Hills.
Air Stagnation Advisory from 4pm Wednesday to 10am PST Saturday for Greater Vancouver Area.
Dense Fog Advisory until noon PST today for Greater Vancouver Area-I-5 Corridor in Cowlitz County.
Wind Advisory from 10pm this evening to 4pm PST Wednesday for Greater Vancouver Area.
PZ...Small Craft Advisory until 10am PST this morning for coastal waters from Cape Shoalwater WA to Cascade Head OR out 60 NM.
Small Craft Advisory from 4pm this afternoon to 4am PST Wednesday for coastal waters from Cape Shoalwater WA to Cascade Head OR out 60 NM.
Small Craft Advisory until 1am PST Wednesday for coastal waters from Cascade Head OR to Florence OR out 60 NM.
Small Craft Advisory until 7pm PST this evening for Columbia River Bar.