Cape Shoalwater WA to Cape Lookout OR between 60 and 150 NM Offshore Forecast
|Today...W To Sw Winds 15 To 25 Kt. Seas 12 To 15 Ft.
|Tonight...W To Sw Winds 10 To 20 Kt, Becoming W To Nw. Seas 11 To 15 Ft. Scattered Showers.
|Sun...W Winds 5 To 15 Kt, Becoming N To Nw 10 To 20 Kt. Seas 9 To 12 Ft. Scattered Showers.
|Sun Night...Nw Winds 10 To 20 Kt. Seas 8 To 11 Ft.
|Mon...W To Nw Winds 5 To 15 Kt, Becoming Variable. Seas 6 To 9 Ft.
|Mon Night...N Winds Less Than 10 Kt, Increasing To 5 To 15 Kt. Seas 6 To 7 Ft.
|Tue...N Winds 10 To 15 Kt. Seas 6 To 8 Ft.
|Tue Night...N Winds 10 To 15 Kt. Seas 6 To 7 Ft.
|Wed...N To Nw Winds 5 To 10 Kt, Becoming W To Nw. Seas 5 To 7 Ft.
|Wed Night...W Winds 10 To 15 Kt. Seas 5 To 8 Ft.
| Area Forecast Discussion
National Weather Service Portland OR
357am PST Sat Mar 2 2024
Upper level troughing over the Pacific Northwest will maintain a cool and showery pattern into the beginning of next week, bringing periods of mountain snow and potential for a rain/snow mix all the way to valley floor each night and evening. Thunderstorms will be possible over much of the area each afternoon. Potential for accumulating lowland snow remains low through the period.
Radar imagery depicts widespread showers ongoing across northwest Oregon and southwest Washington early Saturday morning as a deep and cold upper level trough centered off of Vancouver Island continues to dominate the pattern. Shower activity is being enhanced by a shortwave rotating around the base of the trough and an attendant 987 mb surface low located approximately 75 nm off of the Washington Coast as of 3am Saturday. Conditions are otherwise largely unchanged from those of the past few days as a cold air mass characterized by 850 mb temps around -5 to -6 C remains supportive of snow levels around 1000-1500 ft with wet snow occasionally mixing in all the way to the valley floor, but southerly surface flow and above freezing temperatures in the mid to upper 30s are generally preventing any significant accumulation below about 500 feet. Indeed, webcams from the Eugene area early this morning show showers changing over to snow, leading to some accumulation on grassy surfaces but generally leaving roads clear aside from some slushy accumulation on elevated surfaces. Expect snow to continue to mix in at times through the late morning hours with some light accumulations possible above 500 feet before temperatures rise into the mid 40s and yield all rain during the afternoon. Meanwhile, heavier snow continues today above 1500 feet, with Winter Weather Advisories out for the Cascades and foothills through this afternoon and for the Coast Range and Willapa Hills through Sunday morning.
The other forecast concern today will be thunderstorms as the unseasonably cold air mass aloft supports impressive lapse rates of 8-9 C/km through the lower and mid levels of the atmosphere with model soundings suggesting about 300-500 J/kg SB CAPE by later this afternoon. If we get enough breaks of sun between showers, this environment could yield scattered thunderstorms capable of producing small hail and gusty winds as high as 40-50 mph. Additionally, veering wind profiles with height should yield enough wind shear to sustain a few stronger cells potentially capable of producing a funnel clouds or even a weak tornado. Again, much of this will be dependent on getting a few breaks of sun, as persistent cloudier conditions will result in less instability and more spotty thunderstorm coverage.
Deep upper level troughing will remain over the region through early next week and essentially maintain the status quo as an active, showery pattern persists through at least Tuesday. Will continue to see the potential for snow all the way down to the valley floor during the overnight and morning hours each day even as southerly flow and above freezing surface temperatures continue to limit the potential for impactful accumulations. This continues to be reflected by NBM probabilistic guidance, which caps chances for an inch or more of accumulation in the lowlands at or below 10 percent through the period. Snow will continue to gradually pile up in the higher terrain above 1500 feet. Amounts may flirt with advisory criteria again in the Cascades on Monday but otherwise look to be limited to a a few inches in each period as we head into next week. Finally, thunderstorms will also remain in the forecast through the next few days as the core of the upper trough slowly moves overhead.
Ensemble and deterministic guidance suggest the trough finally shifts east of the region by the middle of next week, yielding a milder onshore flow regime with increasing snow levels and more benign shower potential each day. Roughly 80 percent of WPC ensemble clusters then depict a ridge building over the region late in the week, allowing temperatures to rebound back to seasonal normal values. /CB
A complex of low pressure near Vancouver Island will maintain breezy southwest winds across the coastal waters through the weekend. Models show a pair of surface low pressure troughs that swing across the waters late Saturday, and again Sunday afternoon. These will likely enhance winds and convective activity. Any strong shower or thunderstorm will be capable of producing locally stronger and erratic wind gusts.
A westerly swell will maintain elevated seas into Sunday. Seas will likely hover around 12 to 14 ft through this evening, before gradually subsiding through Sunday and into early next week. Seas are expected to fall below 10 ft Sunday night from north to south across the waters to around 6 to 8 ft on Monday. There is some uncertainty in the forecast though on Monday as another low pressure system moves toward the southern OR or northern CA coast. High pressure then builds across the waters into the middle of next week. /DH
NOAA Portland OR Office: Watches - Warnings - Advisories
OR...Winter Weather Advisory until 4am PST Sunday for Central Coast Range of Western Oregon-Coast Range of Northwest Oregon.
Winter Weather Advisory until 4pm PST this afternoon for Cascade Foothills in Lane County-Cascades in Lane County- Northern Oregon Cascade Foothills-Northern Oregon Cascades- Upper Hood River Valley.
WA...Winter Weather Advisory until 4am PST Sunday for Willapa Hills.
Winter Weather Advisory until 4pm PST this afternoon for South Washington Cascade Foothills-South Washington Cascades.
PZ...Small Craft Advisory until 4am PST Sunday for Columbia River Bar.
Hazardous Seas Warning until 7am PST this morning for Coastal waters from Cape Shoalwater WA to Cape Falcon OR out 60 NM.
Small Craft Advisory from 7am this morning to 4pm PST Sunday for Coastal waters from Cape Shoalwater WA to Cape Falcon OR out 60 NM.
Hazardous Seas Warning until 4am PST early this morning for Coastal waters from Cape Falcon OR to Cape Foulweather OR out 60 NM.
Small Craft Advisory until 10pm PST Sunday for Coastal waters from Cape Falcon OR to Cape Foulweather OR out 60 NM.
Small Craft Advisory until 1am PST Monday for Coastal waters from Cape Foulweather to Florence OR out 10 NM-Waters from Cape Foulweather to Florence OR from 10 to 60 NM.