Wild weather in the West leading into Christmas, with warm weather dominating almost everywhere else

In brief: A major series of atmospheric river-driven storms will impact the West heading into next week, this time focusing more on California. The storm system that hits Tuesday night and Wednesday may be particularly significant there. Elsewhere, windy weather will have a hold on the Front Range & Foothills today in Colorado with dangerous fire weather possible. Warm weather is in control for most places for a good bit of the rest of 2025.

Western Weather is wild!

The last couple posts have been heavily policy-related matters (though I do want to point you to a later night update yesterday from Alan Gerard’s Balanced Weather), so let’s focus mostly on actual weather today, because the West is in for it. The firehose is turned on and will not turn off anytime soon. However, it will take aim at differing parts of the West Coast at different times. The heaviest precipitation will exit Oregon today and push into Northern California while weakening. This leads to a generally calmer day Saturday across the West. On Saturday night and Sunday, the moisture plume revs back up, aiming primarily at parts of southern Oregon and northern California, north of the Bay Area.

That continues Monday, with perhaps a slight downtrend in precip intensity. By later Tuesday and into Christmas Eve, it appears that a significant storm is going to deliver a multitude of hazards to California, including flooding rains, mudslide risk, debris flow risk, strong winds, and extremely heavy snow in the Sierra. This comes in two or three “waves” of action continuing into Christmas Day. Each one gets slightly colder, so snow levels will slowly drop through the event as well. Things reset next Friday and Saturday with a focus on British Columbia, before perhaps the next plume aims at the Northwest again on the following Sunday or Monday before New Year’s.

The key point: The most significant impact of this multi-day atmospheric river event will probably occur Tuesday night through Thursday, focused primarily on California.

The atmospheric river plume that hits California next week is currently forecast to be of high-end strong to low-end extreme intensity. (Center for Western Weather and Water Extremes)

You can see from the chart above that estimates atmospheric river “intensity” for the Bay Area that the intensity picks up today, Sunday, and Tuesday night into Wednesday, with the strongest of the event occurring then (pushing into category 5 level intensity). Let’s talk about total precipitation expected in California. Snow-wise, it looks like a solid 3-to-6-foot type snow event for the High Sierra, with the potential for higher or lower amounts depending on the exact setup that unfolds, but let’s go with that estimate right now as a placeholder based on the most recent data. Liquid-wise? We’re looking at perhaps as much as 15 to 20 inches of liquid equivalent in the northernmost Sierra and just south of the Shasta area.

Forecast rain totals from the Weather Prediction Center for the next week in California exceed 20 inches in some of the high terrain in northern California. (Pivotal Weather)

Expect a flurry of watches, warnings, and advisories to be issued in the next couple days, and expect travel across California to be impacted by this series of storms, especially Sunday into Wednesday.

Front Range & Foothills windstorm

Another round of particularly powerful winds will occur today across the West, with a focus on Colorado again for perhaps the most significant impacts. A combination of low humidity and wind gusts in excess of 70 to 80 mph will be possible primarily west of the immediate Denver and Colorado Springs metros. Red flag warnings are posted in these areas with extremely high fire risk.

A ‘particularly dangerous situation’ for damaging wind and wildfire risk exists today in the Foothills northwest of Denver. (NWS Denver)

Additional wind events seem likely on Sunday and Wednesday as well, though hopefully slightly less intense than today. Precipitation looks to be at a premium in the Front Range and Urban Corridor, with perhaps some good snows possible in northwest Colorado this weekend and later next week, especially for Steamboat and Winter Park.

Warmth continues

The rest of the country looks generally warm over the next 6 to 10 days, with average temperatures well above normal and a flurry of new record highs expected.

Winter cold will take a hiatus through about New Years unless you live in New England, the higher terrain of the West, the Pac Northwest, or Alaska. (NOAA CPC)

Will the pattern change at all as we roll into 2026? We’ll see. For now, just buckle up for a wild ride out West and a warm one for most everywhere else.

Newsy bits

Whatcom County, WA: In Washington, the governor toured damage in Whatcom County from the recent record flooding that occurred in that area. As is often the case, a lot of good things were said after local, state, and tribal officials met, but the real test will be if any of it leads to changes.

Fraser Valley, BC: Meanwhile, over the border in British Columbia, the province’s premier echoed frustration with Canadian federal government inaction on the repeated flooding that is occurring there due to overflow from the Nooksack River into the Sumas Prairie and eventually Fraser Valley. The premier also spoke to Washington’s governor. It appears any concrete relief is going to have to occur with cooperation between the U.S. and Canadian governments.

Denver & Phoenix: Denver and Phoenix have little in common, being on opposite ends of the Colorado River politics spectrum and in different basins of the river entirely. The two cities are scrambling to future-proof their water supplies as the basin’s crunch deepens and negotiators have missed recent deadlines on how to share a shrinking river that 40 million people depend on. Both cities are quietly embracing solutions, from reservoirs to grass removal and planning for the potential of water cuts.

Mount Dora, FL: An update on flood damage from a very localized major flooding event earlier this autumn that occurred north of Orlando.

As atmospheric river events bear down on the West Coast, U.S. weather research that helps public safety and the economy continues to be credibly threatened

In brief: Today we have some commentary on a developing story, where the Trump Administration is planning to dismantle one of the premiere atmospheric research centers in the world. Also, we focus back in the West, where more atmospheric river problems lie ahead.

National Center for Atmospheric Research

I want to start today’s post with a quick note on a story that broke yesterday evening. USA Today reported (and OMB head Russ Vought confirmed) that the Trump Administration would direct the National Science Foundation to dismantle the National Center for Atmospheric Research, or NCAR. The plan is to fully close the historic Mesa Lab in Boulder, CO.

I cannot begin to tell you what a bad, bad, bad decision this is. Objectively so. This will absolutely cripple and devastate weather research in the U.S. While the administration claims that NCAR is “one of the largest sources of climate alarmism in the country,” (it isn’t) almost any climate and weather research done in this country is underpinned in some way, shape or form by NCAR. The administration also claims that vital weather research activities will be “moved to another entity or location,” which seems a bit sus to me given many examples of them causing chaos by dismantling things without adequate replacements or contingency plans. But it also completely misses the forest for the trees. The reason the work done by NCAR has been so critical and important to the science and to industry (and thus the American people) is because of NCAR acting as a (very effective) cog in the weather enterprise wheel. This needlessly breaks up an organization at taxpayer expense for no other reason than they don’t like it. NCAR is not an inefficient organization, nor do they do anything but advance atmospheric science research. In other words, there’s no real value derived by anyone in dismantling the organization.

Just as a slight relevant example from my recent past, and this is something that happens a lot all around the country. At a previous job, we sent another meteorologist to NCAR to take part in a discussion forum with leaders from both there and in the field at large to learn and discuss ways we could incorporate machine learning techniques to potentially improve seasonal or sub-seasonal forecasting (S2S). It would be important to note here that both seasonal and sub-seasonal forecasting is very much a climate-related research topic. Grant proposals, 16-to-45-day models, etc. will use the word “climate” to describe the research here. Nothing about that work is involved in climate change. Since the Trump administration gets uncomfortable about particular words and phrases, they probably see “climate” and assume the worst, when in reality a lot of the “climate research” is actually working to help improve forecasts for the economic and societal benefit of the country — not for pedaling alarmism. Go figure. Meetings like these happen a lot, and it ultimately leads to economic and human benefit, as well as uncovers new avenues of research to travel down.

Anyway, suffice to say, this is a terrible decision that will have significant negative consequences for the country and the economy over the long-term, long after these people leave office. That’s why I am writing about it here. Two organizations within government atmospheric research would be devastating to lose, not that others would not but these two are particularly critical: NOAA’s OAR (Office of Atmospheric Research) and NCAR. The Administration has now tried to gut or is in the process of gutting both of them at zero meaningful taxpayer savings and plenty of meaningful negative consequences for the American public and economy. I must question how that fits a so-called America first agenda.

On to the weather

The big story over the next several days into next week will be another atmospheric river event on the West Coast. Note that NCAR does work to support atmospheric river reconnaissance research that helps improve forecasts of these events. This event is taking aim at the Pacific Northwest right now, where we have numerous watches and warnings posted for flooding (thankfully not as bad as last week), heavy snow, blizzard conditions, and strong winds. In fact, the footprint of wind advisories and high wind warnings is tremendous, extending from the Northwest into the Northern Rockies and Northern Plains.

A whole lotta wind out there! (Pivotal Weather)

One specific area to watch closely today will be the Front Range in Colorado where gusts of 70 to 90 mph will be possible in the higher terrain and wind-prone bases of the foothills. Winds could gust as high as 50 to 60 mph in the Denver area as well later today.

(NWS Denver/Boulder)

Wind gusts on the Plains will be nothing to sneeze at either, with widespread 50 to 70 mph gusts in the Dakotas, Montana, and Wyoming, along with stronger winds at higher elevations.

Maximum forecast wind gusts through tomorrow in the Northern Plains. (Pivotal Weather)

Meanwhile, back on the West Coast, thankfully snow levels are lower with this event than we saw last week. So for Washington that means less rain running off into the swollen river basins. Currently, no rivers in Washington are forecast to hit major flooding levels over the next few days, with several back into moderate flooding. Better news for sure.

River forecasts are all below major flooding across western Washington with this event, thanks in part to lower snow levels. Localized issues may still crop up. (NOAA NWC)

In case you missed it, there was a story that dropped about the Skagit River, and this is a great example of the economic and societal value of weather forecasts. The Army Corps took over dam operations from area utilities that use dams for hydropower. By taking over operations and impounding the water rather than releasing it, about 4 to 5 feet (!) of water was kept out of the river, which prevented an already bad situation from turning into an absolute catastrophe. None of this would have been possible without good coordination, good forecasts, and quick action. This is an example of the value and benefit of weather forecasts and when government agencies and partners perform at their best.

Moving southward, the next target of the atmospheric river will be Oregon. Heavy rain and mountain snows will move in tomorrow through Saturday.

Heavy rain is likely in Oregon, and while mountain snows may drop down to pass levels, there will still be a lot of water being flushed through the system. (Pivotal Weather)

Snow levels will be low today, rise tomorrow, and lower again on Friday. While there may be snow down to pass levels, a lot of water is going to be pushed through the river systems here that are already fairly elevated. So there is some legitimately localized serious flooding risk in these areas.

For California, the next few days will see varying levels of moisture move in, heaviest in far northern California on Friday and for parts of northern and central California on Sunday. The bigger story may be what’s coming next week, where a major storm could overtake all of California, including SoCal. This is highlighted on the 8-to-14-day hazards outlook from Tuesday, showing Christmas Eve, Christmas Day, and Friday in play for a potentially significant rainstorm and Sierra snowstorm.

Potential for a very significant western U.S. storm next week, particularly in California where heavy Sierra snow and flooding all the way into SoCal will be possible. (NOAA CPC)

So, things are busy! Folks in Cali will want to pay attention to next week’s storm, as it does have the potential to be a serious one.

Elsewhere, record warmth is a story. We’re expecting multiple days of records threatened here in Houston, with highs in the 80s next week. The interior West and even parts of the Northeast (Friday) will see record warmth tomorrow into next week. More to come.

Water does not care about your geopolitical borders

I wrote a bit about the flooding this past week in Washington State over at The Eyewall. It was pretty bad. In some places, it was at record levels, others the worst since 1990, and so on. I neglected to look much at how the heavy precip and flooding was impacting Oregon. Or British Columbia.

The Nooksack River sources in North Cascades National Park on Mt. Shuksan. It flows north and then west, eventually dumping into Bellingham Bay off Puget Sound. Because of the topography in that region, when the Nooksack River floods badly, it spills north into the Sumas River. The Sumas sources in Whatcom County, Washington and flows around past the Nooksack and dumps into the Fraser River in British Columbia northeast of Abbotsford.

As is often the case, the reason this is a problem is because of what we chose to do many years ago. This whole area is a leftover flat plain from glacial retreat that acts as a floodplain for the rivers. It is called the Sumas Prairie, but it actually used to be a lake. In the 1920s, the lake was diked and drained. This opened up a bunch of fertile land for farming, as well as reduced flooding on the Fraser River in Canada. But it also is a former lakebed, and water was there for a reason. Thus, in floods like this, the lake is attempting to refill, except now people live where a lake once sat. Essentially, the Nooksack watershed gets higher than the Sumas watershed, and water essentially “spills” downhill into the Sumas, which flows from Washington into Canada.

Maps have borders. Nature does not.

After the bad flooding in 1990, a cross-border group was created to propose flood mitigation measures, specifically near Everson, WA where the Nooksack overflows into the Sumas Prairie. Some modeling efforts were undertaken, some solutions proposed but as time wore on and urgency disappeared, nothing happened, and the effort sort of ended in 2011. After 2021 flooding, the effort was revived. The rub is that a solution that could help alleviate flooding in British Columbia and in Everson would probably cause disastrous effects downriver from there. So, you could fix one problem only to create new ones.

After this event, there will be renewed momentum to try and address this, but the problem is complicated. Some possible ways of solving the problem will take years and are quite costly. Other problems are similar in nature to problems we’ll have to address with respect to dams, which is sediment buildup. In the case of the Nooksack, the river has been constrained for years, when in reality it used to expand and contract. This has allowed for sediment to remain constrained and build up over years, reducing the capacity of the river to hold water, which is challenging even when we don’t factor in that atmospheric river events in the Northwest are becoming stronger. More water from the sky, less capacity to hold water on the ground, a natural floodplain, more flooding. It’s an extremely complex problem underpinned by pretty simple math.

This is not a problem isolated to Washington and British Columbia. On the other side of the countries, flooding problems led to the International Joint Commission (created from the 1909 Boundary Waters Treaty to investigate and come up with joint solutions for U.S.-Canada water challenges) to propose solutions to flooding on the Lake Champlain-Richelieu River basin shared between Quebec, Vermont and New York. The IJC has not yet been involved with the issues in Washington and British Columbia.

Borders exist on this map but as a secondary feature to the water basins themselves.

Locally in my world, there’s an issue right now between Harris County and Montgomery County in Texas. A proposed development in Montgomery County west of a particularly flood prone community in the Houston area (Kingwood in Harris County) forced a Harris County precinct commissioner to push out a high-level resolution requesting that Montgomery County ensure the development adopts Harris County’s minimum drainage standards. Montgomery County has generally weaker standards for developments than does Harris County. In this instance, their choices could directly impact the outcomes for people that do not live in their jurisdiction.

In Canada, Abbotsford’s mayor is not happy with Canada’s federal government or with their neighbors in Washington. In addition to the issues around Lake Champlain and the Richelieu, the IJC did adjudicate and come up with a bunch of recommendations after the horrific 1997 Red River of the North flood that impacted the Upper Midwest and Manitoba. In 2017, they issued a report showing how a good chunk of the effort had succeeded. In Asia, there have been and will continue to be tensions over how countries, in particular China and India manage substantial quantities of water that source in their regions and flow into other nations. In Africa, dam building on the Nile in Ethiopia has created significant tension downstream in Egypt where they believe they have superior water rights on the river.

At what point does it become one community’s responsibility to ensure an adjacent one is not negatively impacted by decisions they make? Look at the Colorado River for one. This is less about flooding and more about water rights, but there are substantial tensions between the upper and lower basins (not to mention tribal nations) over this question. These are not easy problems to solve. But they do require coordination and cooperation. We have that to some degree with the Colorado River, which is governed by the 1922 Colorado River Compact. But when you have a patchwork of requirements and regulations rather than a single agency overseeing an entire region it can make for difficulties, such as in Southeast Texas, where decisions made in rapidly growing counties can impact many neighborhoods in the Houston area. The counties bordering Harris County have grown by nearly 1 million people in the last 15 years. Harris County itself has grown by nearly a million people in that same time. The growth is likely to continue. A formalized regional regulatory approach to flooding in this area is not currently in progress.

But these are the things we’re going to need to be thinking about as flooding likely continues to worsen. Climate change will get the oxygen for a lot of these issues. And it’s obviously a major factor. But it’s not just climate change. In the case of the Sumas/Nooksack flooding, it’s pretty much because we chose to drain a lake in the 1920s that existed for this specific reason, and we decided to constrain the flow of the river leading to sediment buildup and less room for water. In the Houston area we are eradicating prairie and former farmland in differing jurisdictions with differing requirements for building and quickening runoff. In the Colorado River, we are sharing a scarce resource and have dammed the river up. Rather than treating the Washington-British Columbia problems as an unfortunate circumstance from an extreme weather event, it should be a (yet another) wake-up call about some of the decisions we make as people in charting our growth.

Record flooding prompts trouble in parts of western Washington, and a look at record cold in the Midwest this weekend

In brief: Near-record flooding is ongoing or forecast to occur north and east of Seattle today, tonight, and tomorrow leading to dire warnings in a few locations in western Washington. Another round of precipitation is likely next week, but the hope is that temperatures will cool off some, lowering snow levels and mitigating another wave of flooding concerns. Also below, we talk about record cold in the Midwest this weekend, and follow-up warmth in the run up to Christmas.

Pacific Northwest flooding focus

Let’s get caught up on the flooding in Washington State, where both the Snohomish and Skagit Rivers are going ballistic.

Check this video out from Snoqualmie Falls last night. Wild. This is not a typical Pacific Northwest rain. High snow levels and a double-barreled, prolonged category 4 atmospheric river event have triggered some extreme flooding concerns in the region.

Washington State atmospheric river observations and outlook show a couple day-break awaiting before the next round of rain and snow. (Center for Western Weather & Water Extremes)

Rainfall over the past 72 hours has been quite extreme in the mountains, and much of the concern right now is because it’s so mild. The low temperature in Seattle yesterday was 53 degrees, a record warm low for the date, and only 3 degrees shy of the warmest December low temperature on record there. Snow levels have been up around 5,000 feet or higher in spots.

Rainfall over the last 72 hours ending around 9 AM PT on Thursday (NOAA)

You can look at the map above and see a couple things. First, some of the mountains have seen north of 15 inches of liquid in the last 72 hours. 19 inches of liquid at the Lynn Lake SNOTEL site, all of it rain. Second, you can clearly see an Olympic rain shadow over the Seattle metro, which has spared the city of Seattle at least any real severe issues. However, all this water in the mountains? It has to go somewhere.

The Snoqualmie Falls video above is wild, and the water coming over the falls peaked around 70,000 cubic feet per second (cfs) last night, shy of the 78,000 cfs record. The river level was around 20 feet, which is just shy of the top 3 from 1990, 2006, and 2009. Downstream, the river peaked about 1.5 feet shy of the record at Carnation.

(NOAA)

Meanwhile, on the Snohomish River at Monroe, a record crest is expected later today.

(NOAA)

The current forecast has it cresting about 3 feet above the record later today, but the current observed levels are running probably just shy of that pace. Either way, it will be near or above the record when it crests. At Snohomish, the river has established a new preliminary record crest of 33.89 feet, besting the 33.5 feet set in the 1990 flood.

(NOAA)

To the north, the Skagit River should crest a couple feet above its record levels. This forecast is lower than yesterday but still pretty catastrophic for this region. At Mount Vernon, we’re looking at around a 39 foot crest, compared to the record of 37.4 feet, also from 1990.

(NOAA)

To the south, the Cedar River at Renton will also probably set a record tomorrow morning, when it reaches north of 17 feet.

(NOAA)

That river’s record? Also from 1990.As noted in this morning’s hydrologic discussion for the area, inundation near the rivers between Everett and Mt. Vernon is likely, and the threat of landslides remains as well.

Hydrologic discussion from the National Water Center this morning. (NOAA NWC)

In addition, the NWS in Seattle has issued a flash flood watch for the Skagit River below Sedro-Wooley for dam and levee failure risk through Friday night.

Bottom line, it’s a mess, not everywhere but over a wide swath of northwestern Washington State. Flood warnings are also in place in parts of northern Idaho and Montana as well.

As things settle down tomorrow and Saturday, our attention will shift to the next AR event, which looks poised to crash ashore beginning on Monday or Tuesday. This one will start quite warm as well, but fortunately it does look like temperatures will drop off a good 5 to 10 degrees compared to the ongoing event. This should lower snow levels down to more typical elevations and lead to less of a full-scale runoff event like the ongoing one. Still, we will probably be looking at a fair bit of precipitation from this event.

12z European model forecast liquid over the next 10 days showing anywhere from 10-13 inches in the mountains, much of it this time falling as snow. (Pivotal Weather)

Liquid equivalents will be on the order 10 to 13 inches in the Cascades next week, or as it stands now at least. While the amount of water flowing into the river systems will be mitigated by the snow that accumulates and sticks around, we will probably see another round of (less extreme) flooding risks next week in the Northwest.

Near record cold

Meanwhile, as this whole pattern evolves, we get one last real serious shot of cold in the Eastern U.S. this weekend, peaking on Sunday. This one will probably be the coldest we’ve seen this winter across the Midwest, with numerous record lows being threatened on Sunday morning.

Record lows at risk on Sunday morning in the Midwest (NOAA)

Forecast lows will be near 8 degrees in Indianapolis, 14 in Louisville, 11 in Cincinnati, and 13 degrees in Dayton. Wind chills of -10 to -20 will be widespread in the Midwest with -30s in Minnesota.

Back to warm

But thereafter, the pattern changes again. The 5-day average 500 mb height anomaly map is shown below for the period ending on Sunday evening, December 21st.

A broad, extremely warm weather pattern will expand across the southern two-thirds of the country late next week. (Tropical Tidbits)

A very broad, very strong ridge of high pressure will setup across the Southwest and Plains. This may be close to record strength for this late in the calendar year. That would translate to high temperatures, possibly numerous record highs and record warm minimum temperatures across the country in the days before Christmas. For cold, you may only be able to look to New England, the Pacific Northwest, and the extreme Upper Midwest. Stay tuned.