516 FXUS66 KPQR 260510 AAB AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 909 PM PST Mon Dec 25 2023 Updated aviation/marine. .SYNOPSIS...It is a rainy grey day across the region. Cold front offshore will swing inland later tonight, with showers afterwards. Low pressure will sit offshore rest of the week, sending fronts inland. This will maintain unsettled weather, with rain/showers at times, along with seasonal temperatures. && .UPDATE...Monday evening through Monday night...Temperatures at and near river level across the central Columbia River Gorge were around two to five degrees above freezing, and are no longer expected to dip below freezing again Monday evening. Therefore, no additional ice accumulation is expected along I-84 from Hood River westward. As such, the Winter Weather Advisory has been cancelled for the central Columbia River Gorge. Meanwhile, the Ice Storm Warning for the south WA Cascades and the Winter Weather Advisory for the far north Oregon Cascades have both been extended through 4 AM Tuesday, which matches the expiration time for the Ice Storm Warning that remains in effect for the Upper Hood River Valley. This is to account for the additional ice accumulations of 0.10-0.25" expected in these areas for elevations above roughly 500 feet. After 4 AM Tuesday, precipitation should come to an end very quickly according to the latest suite of hi-res model guidance. -TK && .SHORT TERM...Monday night through Wednesday... Warm front has pushed north of the region as of early afternoon. Still have plenty of clouds, along with rain/drizzle across region, though rain has ended towards far south parts of the area. In fact, temperatures have pushed back into the lower 50s for areas south of a Newport to Albany line. To the north, still cool, with 40s. Cold front still offshore, with rain increasing through this evening. NOAA satellite imagery showing shortwave about 350 miles west of Newport. As that wave moves farther to the north, the cold front will begin to pick up forward speed towards the coast. That front will push onshore later tonight, and across the interior after midnight. As such, will see rain increasing across the later this afternoon, with rather wet evening on tap across the region. Pressure gradients will remain tight enough to maintain gusty southerly winds along the coast through Monday evening, with gusts 50 to 65 mph on the exposed headlands and open beaches. Current timing of the front arrival to the coast (~10 pm) would suggest strongest winds will be from 6 pm to 10 pm. Afterwards, winds ease. Now, with the continued offshore flow in the region, will see little if any temperature change in the mid-Columbia Gorge and Hood River Valley, as well as the valleys in eastern Skamania county. As such, will continue to see freezing rain in those areas, though most ice accumulations will be away from the Columbia River. This will continue through at least this evening. Additional ice accumulations of Trace up to perhaps as much as 0.10 for the mid-Columbia River Gorge, most of which will be up off the river level area. But, in the Hood River Valley and valleys in eastern Skamania county, could see another 0.10 to 0.33 of an inch (storm total ice of 0.40 to 0.80 inch). So, will maintain Winter Weather Advisory for the mid-Gorge through this evening, and the Ice Storm Warning for Hood River Valley and eastern Skamania county until later tonight. At that point, should see rain decreasing, and temperatures rise as cold front pushes milder air into the region. Showery later tonight, as colder air filters inland and boost instability aloft. But, does appear air mass begins to stabilize again by midday Tuesday. As such, this would favor decreasing showers. Would not be surprised if most of Tuesday afternoon ends up being mostly dry. Will trend forecasts that direction. But, any break does appear to be relatively short-lived. Broad area of lower pressure offshore will line up a parade of fronts. Warm front will lift north across the region later Tue night, mostly brushing the coast with spotty rain. Cold front will slowly approach later Tue night and moving onshore during the day Wednesday. So, more rain, with snow in the Cascades. Interestingly, could be cold enough to support spotty light freezing rain in the Upper Hood River Valley again. Bit more colder air aloft behind this front. Will see plenty of showers for later Wed afternoon/Wed night. Will mention chance of thunderstorms on coastal waters as well. /ROCKEY .LONG TERM...Thursday through Sunday... Not much change, as broad low pressure remains offshore. Showers on Thursday, with another front arriving on Friday. Not particularly strong front, but enough that looks to maintain rather wet day for Friday. Unsettled weather continues into the next weekend. /Rockey && .AVIATION...06z TAFs: Occluding frontal system is spreading another round of rain onshore as the cold frontal portion approaches the coast. Expect conditions to deteriorate rapidly to IFR along the coast, with a brief period of +RA and S winds gusting 35-45 kt as the front moves onshore between 06z-07z. Behind the front, coastal winds will shift more SW and decrease quickly after 06z or 07z. Some improvement is expected after that, with guidance suggesting VFR is most likely by 12z. Once conds go VFR along the coast, it appears a return to offshore winds will keep conds VFR for the remainder of the day. Most inland areas have improved to VFR, except for an area of IFR near KSLE/KMMV where cool Gorge outflow to the north is meeting higher-dewpoint air to the S-SW. Guidance keeps trying to dissipate this area of low stratus right away, but guidance also continues to underestimate the staying power of the Gorge outflow. Would give about a 50/50 chance that these IFR cigs will lift to MVFR or even VFR as the cold front moves across the Willamette Valley around 08z simply due to turbulent mixing along the front. East winds will ramp back up through the Columbia Gorge Tuesday, so chances of low cigs will increase again for Willamette Valley terminals west of the river as cold air damming resumes along the east slopes of the Coast Range. East winds remain strong near the west end of the Columbia Gorge, with gusts 25-35 kt until the cold front passes through the Gorge around 09z-10z. Winds will diminish for a few hours after that, but will ramp back up later Tuesday as the next frontal system approaches. Note that within the upper Hood River Valley, freezing rain is expected. Any freezing rain will accumulate on exposed surfaces. Freezing rain should begin to dissipate around 12Z Tuesday. PDX AND APPROACHES...East winds continue to hang on at KPDX as of 0430z, and will remain 15-20 kt with gusts 25-30 kt until the surface cold front moves through around 08z. After that, winds will slacken but may never completely lose their easterly component before east winds ramp up ahead of the next system Tuesday. The offshore flow will maintain mostly VFR conds, though a few hours of MVFR are possible from when E winds slacken around 08z until they increase again around 15z. Weagle && .MARINE...Strong cold front is moving into the coastal waters with widespread Gale Force winds and more localized Storm Force gusts. Will leave Storm Warning in place, then winds shift SW and diminish behind the cold front. Once the Storm Warning comes down, will need a Hazardous Seas Warning for seas in excess of 15 ft through much of the day Tuesday. Will experience a lull in winds Tuesday as the next strong low pressure system develops and moves into the NE Pacific. This system looks fairly similar to the one we dealt with today, with the strongest winds remaining in the outer waters and perhaps even further offshore due to a strong easterly component to MSLP gradients. This will be a theme over the coming days as broad, strong low pressure sets up shop over the NE Pacific, with individual disturbances pinwheeling around it and brushing the Pac NW coast with gusty winds from time to time. By Wednesday or Thursday, guidance suggests all the storminess offshore will build seas to 20-25 ft across our waters. Weagle && .BEACH HAZARDS...Seas are building along the coast this evening as a strong cold front approaches. Seas had already built to 19 ft at 11 sec at Buoy 46050 as of 8 PM, and the front had not moved over the buoy just yet. This is tracking very well with GFS wave spectral guidance, so we suspect seas will top out at 20-21 ft from this ongoing event. Seas will come back down a bit Tuesday morning, but remain in the low to mid teens with periods in the 13-15 sec range, so the sneaker wave threat will remain elevated. A more substantial round of high surf will arrive across the waters late Wednesday into early Thursday. The current projected swell, swell period and angle of incidence would place us solidly in high surf advisory criteria. It's not out of the question this event will reach high surf warning criteria, which is typically when beach erosion and large waves impacting infrastructure along the coast has occurred in the past. However, statistical guidance with regards to swells is still rather limited so it's tough to pin down the probability of this happening. Weagle/Neuman && .PQR WATCHES/WARNINGS/ADVISORIES... OR...High Wind Warning until midnight PST tonight for North Oregon Coast. High Surf Advisory until 6 AM PST Tuesday for Central Oregon Coast-North Oregon Coast. Winter Weather Advisory until 4 AM PST Tuesday for Northern Oregon Cascades. Ice Storm Warning until 4 AM PST Tuesday for Upper Hood River Valley. WA...High Surf Advisory until 6 AM PST Tuesday for South Washington Coast. Ice Storm Warning until 4 AM PST Tuesday for South Washington Cascades. PZ...High Surf Advisory until 6 AM PST Tuesday for Coastal waters from Cape Shoalwater WA to Cape Falcon OR out 10 NM. Storm Warning until 1 AM PST Tuesday for Coastal waters from Cape Shoalwater WA to Florence OR out 10 NM-Columbia River Bar-Coastal waters from Cape Shoalwater WA to Florence OR from 10 to 60 NM. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland