Cascade Head to Florence, OR out 10 NM Marine Forecast
|Rest Of Today...Sw Wind To 5 Kt. Wind Waves Sw 1 Ft At 4 Seconds. Nw Swell 2 Ft At 9 Seconds. Widespread Dense Fog And A Chance Of Showers In The Morning, Then Areas Of Dense Fog In The Afternoon.|
|Tonight...N Wind To 5 Kt. Wind Waves N 1 Ft At 4 Seconds. Nw Swell 3 Ft At 9 Seconds. Areas Of Dense Fog In The Evening. Patchy Dense Fog After Midnight.|
|Wed...N Wind 5 Kt. Wind Waves N 1 Ft At 4 Seconds. Nw Swell 3 Ft At 9 Seconds. Patchy Dense Fog In The Morning.|
|Wed Night...Nw Wind 5 Kt. Wind Waves W 1 Ft At 4 Seconds. Nw Swell 3 Ft At 9 Seconds.|
|Thu...Se Wind 5 Kt, Veering To W In The Afternoon. Wind Waves Se 1 Ft At 4 Seconds, Shifting To The W At 4 Seconds In The Afternoon. Nw Swell 3 Ft At 10 Seconds.|
|Thu Night...N Wind 5 To 10 Kt. Wind Waves N 1 Ft At 4 Seconds. Nw Swell 3 Ft At 10 Seconds.|
|Fri...N Wind 5 To 10 Kt. Wind Waves 2 Ft. Nw Swell 3 Ft.|
|Sat...Nw Wind 5 To 10 Kt. Wind Waves 2 Ft. Nw Swell 4 Ft.|
| Area Forecast Discussion|
National Weather Service Portland OR
447am PST Sat Dec 2 2023
Snow continues through today in the Cascades with snow levels rising overnight tonight. The first in a set of atmospheric rivers moving through the region is impacting the area today. A stronger atmospheric river will cause flooding impacts across the region tonight into Sunday. Rain continues Monday with another strong atmospheric river Monday night into Wednesday. Will see heavy rain, warmer temperatures, and gusty winds with each system with flooding impacts continuing into next week.
Saturday through Friday...Snow is continuing over the Cascades early Saturday morning with snow down to around 3500 feet as of 3am PST. Snow levels will remain around 3000 to 4000 feet through the day with the heaviest snow above 5000 feet. An additional 1 to 2 feet of snow is expected above 5000 feet, with up to an additional 6 inches above 3000 feet. A Pacific frontal system is beginning to push inland, bringing a band of moderate widespread rain and breezy winds. This will be the first of three consecutive atmospheric rivers (AR) to move through the Pacific Northwest. The front will move from northwest to southeast into central Oregon through the morning hours, clearing the Cascades in the afternoon, bringing rain ahead of and along the front, with isolated showers behind it in the afternoon. Lightning is also possible along and ahead of the frontal system, and some has already been observed in north and central Washington this morning. Rain amounts with this system will be less than the next two, with anywhere from 0.25 to 1.25 inches in the lower elevations and 0.5 to 2.5 inches over the coast and higher elevations through this evening. Breezy winds are a concern early this morning with gusts up to 35-45 mph, except up to 45-55 mph for wind prone areas along the coast and over terrain.
The next AR will begin to push into the area this evening. Both GEFS & Euro ensemble guidance indicate integrated vapor transport (IVT) will be around 700-800 kg/ms, which would suggest this would be a high moderate to low strong AR. For perspective, IVT with today's AR will peak around 500 kg/ms, around a low moderate AR. The associated surface front with this system will move in from the south, moving through southern Oregon overnight tonight and into NW Oregon and SW Washington Sunday morning. This will cause snow levels over the Casacdes to rise to above pass level this evening, rising even higher to 7000 to 8000 feet overnight. This means all precipitation will fall as rain over the Cascades by Sunday morning. Pre- frontal rain will begin this evening in the southern counties, with heavier rain pushing north late tonight into Sunday. Periods of heavy rain are expected with rain rates over 0.25 inch per hour over the Coast Range, Willapa Hills, and Cascades and 0.1 to 0.25 inch per hour elsewhere during this time period. Total rain amounts with this system through Sunday night are forecast around 1.25 to 2.25 inches for the lowlands and anywhere from 2 to 6 inches over the Coast Range and Cascades (40-70% probability of over 5 inches). Localized amounts of up to 7 to 8 inches are possible (10-15% probability) in orographically forced areas. This is a significant amount of rain to fall in a fairly short period of time, which combined with snow melt from rain falling on recent snow will produce flooding impacts. Please see the hydrology section below for more information. Gusty winds are also a concern once again, though latest and previous guidance suggests that peak winds will be similar to this morning with gusts up to 35-45 mph, except up to 45-55 mph for wind prone areas along the coast and over terrain.
Rain will taper into light to moderate showers again Sunday evening into Monday. Upper level flow will remain pretty zonal during this time which will keep a decent Pacific moisture stream into the area. Showers through Monday evening will produce an additional 0.25 to 1.25 inch of rain for the lowlands, 1 to 3 inches for the Coast Range and Willapa Hills, and 0.75 to 2 inches for the Cascades. Latest ensemble guidance indicates third AR and associated surface front are slated to move through the area late Monday night through Tuesday night. IVT ensemble forecast with this AR indicate this will be the strongest, somewhere around 750-950 kg/ms, and it will also last longer over NW Oregon and SW Washington, which could produce even more significant impacts than on Sunday. The track continues to push the heavier rain a bit north. NBM guidance for a 48 hour period ending 4am Wednesday indicates a 50-70% probability of 2+ inches of rain for the Willamette Valley north of Lane County into the Portland/Vancouver metro area and an 80-90% for all of SW Washington. NBM also indicates a 50-80% probability of 5+ inches of rain for the Coast Range north of Lincoln County, Willapa Hills, and southern Washington Cascades. Some uncertainties remain in timing and strength of this event for both rain and wind, but confidence is high in another round of moderate to heavy rain causing additional flooding impacts.
For Thursday into Friday, deterministic models and their ensembles want to produce a weak weather system sometime on Thursday into Friday, though timing is very uncertain. This means precipitation chances will continue into the end of the week, though at this time amounts beyond Wednesday look pretty minimal. -HEC
A series of three atmospheric rivers will bring periods of widespread heavy rain to northwest Oregon and southwest Washington this weekend into the middle of next week. The first system, also the weakest of the three, is moving through NW Oregon and SW Washington this morning. The next will bring higher rain amounts (detailed in the forecast discussion above) tonight through Sunday. Snow levels will rise overnight tonight which means mountain snowmelt due to rain falling on the recent snowpack will also be a contributing factor in regards to river flooding concerns. Additional rainfall will occur early next week, with increasing potential for another strong atmospheric river Tuesday into Wednesday. However, uncertainty remains regarding exact rain amounts and timing from Monday onward.
Given the forecast rainfall amounts expected this weekend, river levels will be rising quickly. Most coastal rivers show a 40-60% chance of reaching minor flood stage and a 10-30% chance of reaching major flood stage in the next 10 days. This includes the Wilson River and Trask River near Tillamook, the Naselle River near Naselle, the Nehalem River near Foss, the Nestucca River near Beaver, and the Siletz River at Siletz. Additionally, many other rivers across northwest OR and southwest WA still show anywhere from a 30-50% chance of reaching at least minor flood stage in the next 10 days, except for the mainstem Columbia and Willamette Rivers where the chance of reaching minor flood stage remains lower, around 5-10%. To view current and forecast river stages for any river gage location across southwest WA and northwest OR, visit https://water.weather.gov/ahps2/index.php?wfo=pqr
Lastly, urban flooding is also possible this weekend, especially in low-lying areas with poor drainage. If you have gutters and/or storm drains that still need to be cleared out, now is the time. Significant ponding of water and localized roadway flooding is expected on roads. Any motorists with travel plans this weekend should also allow extra time for their commute as hydroplaning will be a risk. Never drive through flooded roads. -HEC
Current observations at buoy 46050 as of 330am PST Saturday show southwesterly winds at 20-25 kt with gusts up to 40 kt as a frontal system moves through the waters. Seas are also building to 14-17 ft. Expect winds to weaken to sub-Gales after mid-morning Saturday. Following these Gales, winds will generally be westerly at 10-15 kt. However, seas will remain elevated today so a Hazardous Seas Warning will be in effect from late morning Saturday through the evening.
Saturday night into Sunday morning, the next frontal system will approach the waters from the southwest. This will bring another round of southwesterly winds gusting up to 40 kt across the waters from Cape Falcon, OR southward. Therefore, another Gale Warning has been issued for these areas beginning Sunday night. Seas will remain between 10-14 ft.
A very active weather pattern persists Sunday through early next week, with a greater than 80% chance for additional rounds of Gale force gusts over the waters. Sub-Gale force winds are possible after Tuesday, however seas will remain elevated and build up to 18-20 ft at 16-17 seconds through mid-next week. This will also maintain the threat of sneaker waves along our coast. -Alviz
NOAA Portland OR Office: Watches - Warnings - Advisories
OR...Flood Watch through Tuesday afternoon for ORZ001>008-010-012. Beach Hazards Statement from late tonight through late Wednesday night for ORZ001-002. Wind Advisory until 10am PST this morning for ORZ006>008. High Wind Watch from late tonight through Sunday evening for ORZ006>008. Winter Storm Warning until 10pm PST this evening for ORZ011-013.
WA...Flood Watch through Tuesday afternoon for WAZ020>022-039-040. Wind Advisory until 10am PST this morning for WAZ039. High Wind Watch from late tonight through Sunday evening for WAZ039. Winter Storm Warning until 10pm PST this evening for WAZ019. Beach Hazards Statement from late tonight through late Wednesday night for WAZ021.
PZ...Gale Warning until 8am PST this morning for PZZ210-251>253-271>273. Hazardous Seas Warning from 8am this morning to 10pm PST this evening for PZZ210-251>253-271>273. Gale Warning from 10pm this evening to 10am PST Sunday for PZZ252-253-272-273. Small Craft Advisory from 8am this morning to 10am PST Sunday for PZZ210. Small Craft Advisory from 10pm this evening to 10am PST Sunday for PZZ251-271.