Extreme Temperature Diary- Friday December 12th, 2025/Main Topic: Washington Flood Exacerbated by Climate Change – Guy On Climate
Dear Diary. As we have witnessed over the past couple of decades, climate change makes wet weather systems wetter, whether they be from hurricanes or in this case atmospheric rivers. A warmer atmosphere holds more moisture, which can be released in torrents by various weather systems.
In the case of flooding that occurred earlier this week in the Pacific Northwest and British Columbia, a record warm air mass developed over the Southwest, which interacted with an atmospheric river that also got strengthened because the jet stream strengthened:
The jet ushering in moisture along the atmospheric river got faster because it got more energy from the heat dome that developed over the Southwest and a portion of the polar vortex extending southward from Alaska. In other words, the gradient represented by height contours in the below Pivotal Weather image tightened much more than usual because of the southwestern heat dome, which is an indication of a faster jet:
For more details on Washington flooding, here is a Washington Post article:
Record moisture leads to destructive flooding in Washington state – The Washington Post
Destructive flooding hits Washington state, with six rivers at dangerous levelsSevere flooding has led to evacuation orders and water rescues. More rain is expected Thursday.December 11, 2025
 From left, deli owners Zahra Hesham, Hanadi Hesham and Karrar Hesham, along with Yousif Hesham, back, walk through floodwaters after checking out their store in Auburn, Washington, on Wednesday. (John Froschauer/AP)
By Joshua Partlow and Ben Noll
MOUNT VERNON, Wash. — An atmospheric river, whose moisture spanned a remarkable 7,000 miles across the Pacific Ocean from the Philippines to the Pacific Northwest, caused record river levels and destructive flooding across Washington state this week and forced thousands to evacuate while authorities wait to see if levees will hold.
According to an analysis of weather data, moisture levels with this storm may have broken December records by as much as 6.7 percent, considering based on records dating back to 1940.
 A moisture plume spanning the length of the Pacific Ocean fed into an atmospheric river that soaked the Pacific Northwest this week. (Ben Noll/Data source: ECMWF/ERA5)
This includes portions of Snohomish, King, Chelan and Kittitas counties in Washington, east of Seattle, where more than a foot of rain had fallen in some high-elevation areas in the Cascades since the start of the week. Similar rainfall totals were observed near the Olympic Mountains.
Swaths of the Pacific Northwest are considered hot spots, where rising moisture flows in the atmosphere have frequently driven heavy rainfall.
 An atmospheric river may have caused record moisture levels in portions of the Pacific Northwest, according to forecasts issued Wednesday compared with historical data since 1940. (Ben Noll/Data source: ECMWF/ERA5)
As of Thursday, parts of six rivers in Washington had reached major flood stage — the highest level on the scale — including the Skagit, Skykomish, Snohomish, Snoqualmie, Cedar and Cowlitz rivers.
The rising floodwaters have forced thousands of people from their homes in western Washington, where the National Weather Service has warned of potentially catastrophic and life-threatening floods.
Dozens of roads and highways have been closed by flooding across wide swaths of the state. Water rescues unfolded near Fall City, Washington, east of Seattle.
One of the main crisis spots on Thursday was along the Skagit River, which flows down from the Cascades north of Seattle and empties into the Puget Sound.
Authorities have called on people within the 100-year-floodplain of the river to evacuate as the still-rising river could peak sometime overnight at record levels, testing a levee system that suffered damage during a 2021 flood. Schools in Skagit County have closed Thursday and Friday.
“This situation is unpredictable, it’s dangerous, we don’t know what exactly will happen when those flood waters come through,” Robert Ezelle, director of Washington state’s emergency management division, told reporters at a news conference on Thursday afternoon at a college in Skagit County.
Authorities are expecting flood waters along the Skagit River in the Mount Vernon area to surpass the record level by two feet, peaking overnight Thursday or Friday morning.
“This system coming through will test the work that was done on the levees,” Ezelle said.
The floods have closed rural highways and cut off mountain towns and caused landslides in wildfire burn scar areas such as in Stehekin, a remote community reachable by boat along Lake Chelan in eastern Washington, authorities said.
In Sedro-Woolley, a city along the Skagit River, residents who live close to the river have scrambled to get out of harm’s way over the past two days. Rebecka and Rafael Perez evacuated from their riverfront RV park on Wednesday and are staying in a hotel to wait out the flood. They came back to the police cordon on Thursday to watch the steadily rising river.
“It’s completely gone,” Rebecka Perez, 50, said of the site of her former home. “It’s completely underwater.”
Many people in Sedro-Woolley remained in the city, with shops and restaurants open downtown. Among the soggy forested foothills, it takes a lot of rain to impress locals. But the scale this time has made many take notice, particularly the warnings that levees and dikes could fail.
“I’ve lived here for 22 years, and I’ve never seen flooding like this,” said Staci Hasenohrl, 40, who lives a few blocks from the evacuation zone but has chosen to stay so far. She said she’s never been scared of flooding before but “my fight-or-flight was pretty high this time watching how high it was supposed to be.”
In Mount Vernon, the swollen and silty Skagit River crept up slowly throughout the afternoon, sweeping along massive trees and clumps of logs. Residents gathered on a riverside bike path to watch the river and take photos and selfies as the debris raced past.
Skagit County commissioner Lisa Janicki warned residents to stay away from the levees and dikes along the river.
“People are walking their dogs on the tops of these dikes that may fail,” Janicki said during the news conference. “We’re hoping they hold. But there’s seepage in some spots.”
“Get off those dikes. Get home. And take care of your loved ones,” she added.
An estimated 78,000 people live in the flood zone along the Skagit River but local authorities said they expected to house about 3,800 evacuees at various shelters in the area.
Washington Gov. Bob Ferguson (D) said he’s asked the Trump administration for an emergency declaration to help support the recovery when the waters recede. Some 100 National Guardsmen have been deployed and 200 more were en route, state officials said.
“It’s a very, very serious situation,” Ferguson said during a news conference on Thursday afternoon.
Rain is forecast to continue across western Washington on Thursday, although its intensity is expected to gradually wane as the core of the atmospheric river pushes northward into British Columbia by Friday. As part of the same weather system, heavy snowfall is forecast across southern Alberta and Montana on Friday.
Dry weather is forecast across Washington for Saturday, although more heavy rain is expected from Sunday into early next week — as a new atmospheric river joins forces with the current one, sending copious amounts of moisture into the region.
Another atmospheric river is forecast to hit the Pacific Northwest early next week. (Video: Ben Noll/Data source: ECMWF)
Extreme weather By Joshua Partlow Joshua Partlow is a reporter on the The Washington Post’s national desk. He has served previously as the bureau chief in Mexico City, Kabul, Rio de Janeiro, and as a correspondent in Baghdad. follow on X@partlowj
 By Ben Noll Ben Noll is a meteorologist passionate about explaining the why behind the weather, extreme events and climate trends. He has expertise in data analysis, supercomputer-driven graphics and forecasting weather worldwide. follow on X@BenNollWeather
Here are some “ETs” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Mid-PM temps within a few hundred feet of sea level in Central Valley (low 40s F) quickly rise to (low 70s F) just 2,000ft up in surrounding slopes. That's an inversion magnitude of ~30F/2,000ft! Amazingly, airmass atop fog layer is *record warm* despite damp chill right at sfc. — Daniel Swain (@weatherwest.bsky.social) 2025-12-11T22:47:04.000Z
Monthly global climate data update from @climate.noaa.gov for the month of November 2025.
Third hottest month of November since 1850.
datagraver.com/climate-data...
#climate — Datagraver (@datagraver.com) 2025-12-11T19:19:21.186Z
Shell facing first UK legal claim over climate impacts of fossil fuels
www.bbc.co.uk/news/article... — Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-12-11T21:56:40.467Z
This week, I explore B Corps doing good and the toll of seasonal waste. I've also collected a host of ideas on how our choices can reduce waste, support communities, and restore nature — from thrifted treasures to shared experiences, and giving that supports families and ecosystems around the world. — Katharine Hayhoe (@katharinehayhoe.com) 2025-12-11T22:56:43.287Z
Glaciologist & climatologist Ellen Mosley-Thompson pioneered ice-core paleoclimatology, an area of #climate science focused on studying past climates by analyzing ice cores. #WomenInSTEM #science #glaciers
It's International Mountain Day. 2025 Theme: #GlaciersMatter — Admirable Women (@admirablewomen.bsky.social) 2025-12-11T16:25:26.215Z
Next Monday, 1–2 pm, our lecture series sets sail into climate history! Prof. Eleonora Rohland explores "DOLDRUMS" – how old ship logs reveal past climate patterns and the secrets of a unique windless Atlantic zone. Join us on Zoom – register below. #earlymodern #climate #maritimehistory #history 🗃️ — Lucas Haasis (@lhaasis.bsky.social) 2025-12-12T10:37:39.552Z
Can someone please explain how humanity is supposed to adapt to this?
Climate change is making these severe events more severe and more frequent. No time to wait. #ActOnClimate
#climate #energy #renewables #spain — Mike Hudema (@mikehudema.bsky.social) 2025-12-12T19:07:33.449Z
TODAY 1 pm: Our climate scientist Daniel Swain will discuss the historic flooding in Washington, the record-warm airmass across the West & Central Valley tule fog, and possible rain in California — UC Agriculture & Natural Resources (@ucanr.edu) 2025-12-12T19:03:31.704Z
Central California is currently experiencing one of the most remarkable temperature inversions I've ever seen in this part of the world. The Central Valley remains miserably damp & chilly under dense fog layer, but it's balmily warm & sunny just 2,000ft up nearby mountain slopes! — Daniel Swain (@weatherwest.bsky.social) 2025-12-11T22:46:57.000Z
Temperatures have been above freezing for 146 straight hours at the summit of Palisades Tahoe. #CAwx — Anthony Edwards (@edwardsanthonyb.bsky.social) 2025-12-11T17:34:20.258Z
This has been a striking, and strikingly persistent, pattern for much of December: sharp cold toward the Midwest and Northeast, and unusual warmth from the Rockies westward. (But not in central California, where unusually chilly air and "tule fog" have been in place for days). — Bob Henson (@bhensonweather.bsky.social) 2025-12-12T20:41:51.881Z
Managing energy demand one of the most powerful and overlooked options. EU saved 60bn cubic metres gas 2022 - 2024 via renewable deployment and energy efficiency, accompanied by fall in coal and oil.
www.ft.com/content/45d4... — Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-12-12T12:06:11.232Z
Australia just launched the national Vehicle-Grid Network!
Every EV & PHEV owner will soon be able to sell power back to the grid and get paid.
Your car = mobile battery that literally makes you money while parked. This is HUGE. #auspol #climate #ev
www.carexpert.com.au/car-news/aus... — Sydney EV (@sydneyev.bsky.social) 2025-12-12T03:13:33.281Z
#China’s oil demand is expected to “plateau” between 2025 and 2030, as rapid growth of electric vehicles (#EVs) cuts demand for petrol and diesel
www.reuters.com/business/ene... — Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-12-12T12:18:25.671Z
— Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-12-12T12:35:15.181Z
— Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-12-12T12:34:44.272Z
Energy efficiency could save industrial sector four million tonnes of CO2 over 10 years www.businessgreen.com/4523105/ via @businessgreen — Dr Paul Dorfman (@drpauldorfman.bsky.social) 2025-12-12T12:19:50.106Z
We need renewable energy to take a bite out of the climate crisis but also the authoritarianism crisis
Right now we’re just doing oil piracy
open.substack.com/pub/billmcki... — Bill McKibben (@billmckibben.bsky.social) 2025-12-11T20:41:44.570Z
Mihir Rao gets youth a voice to shape their future. 18-year-old Albertan equips youth to influence decision-makers. Mihir is a 2025 I-SEA Youth Climate Action award winner. @climatedesk.org @katharinehayhoe.com @calgaryclimatehub.ca
www.nationalobserver.com/2025/12/08/o... — Patty Lane (@pattylane.bsky.social) 2025-12-11T22:58:07.842Z
#Sky
#Sun
#Sunsets
#Climate
#Photography — michaeledward (@michaeledward.bsky.social) 2025-12-12T13:48:03.755Z
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