Now you see it, now you don't. Near the end of this extremely warm winter, California's snow is rapidly melting. My colleague @castleman.bsky.social shares some striking satellite images. He spoke with @weatherwest.bsky.social about the remarkably rapid loss of snow: www.latimes.com/california/s...

Whew. All signs are increasingly pointing to a significant, if not strong to very strong, El Niño event. I'll have more to say in coming weeks & months, but for now I'll just say that this is increasingly likely to become a major regional-to-global climate driver in 2026-2027.

In case you missed it, the recording is now available via the same link below.

I'll host a short-notice livestream later this afternoon (Mon, 3/2, at 2pm PT) to discuss recent news that winter 2025-2026 was the warmest on record--by far--across the Western United States. I'll discuss snowpack, water supply, and wildfire implications.

Lake Powell is nearing a level where Glen Canyon Dam can’t generate power. Federal officials are considering unprecedented cuts to water releases to keep turbines running — with ripple effects for ecosystems, water users, and the Colorado River Basin. Read the story: buff.ly/LAE9KAx

December 2025 through February 2026 was the 2nd warmest winter on record for the Contiguous U.S. according to Prism climate data. The widespread record to near record warmth in the west easily outweighed the cool temps in the east. 🔥🔥🔥

I'll host a short-notice livestream later this afternoon (Mon, 3/2, at 2pm PT) to discuss recent news that winter 2025-2026 was the warmest on record--by far--across the Western United States. I'll discuss snowpack, water supply, and wildfire implications.

Congress has appropriated the funds to NSF but OMB is delaying the release. When funds are released, NSF, which has lost almost 1/5 of its staff, will struggle to evaluate proposals. Since they have to award the funds, big projects with established PIs will benefit. This is how US science dies.

One year in the federal assault on climate science — a review and prospective

And record-breaking daily-to-monthly high temperatures are occurring, in even more widespread fashion, yet again today. #CAwx #AZwx #NMwx #COwx

#BlueBellFire in #Boulder, CO (near Chautauqua Park) currently burning amid extremely dry and near record-warm conditions (69F and 7% RH). Lack of strong winds right now thankfully a major mitigating factor. So far, mostly sfc fire plus occasional torching in confers. #COwx

I am officially issuing a "cool cloud watch" for NorCal! The offshore low has entrained subtropical moisture; in addition to bizarrely muggy airmass, this will contribute considerable instability & subsequently to widespread convective clouds & some thunderstorms this PM. #CAwx

Scattered showers & thunderstorms will likely occur in this remarkably warm/humid/conditionally unstable airmass this wknd across NorCal. Best odds in Sierra, northern foothills, and northern Sac Valley. But isolated showers/t-storms possible as far south as SF/Sac as well! #CAwx

In fact, this may be one of the most conspicuously humid airmasses in recent memory across the Sacramento & San Joaquin Valley--with air temperatures in the 70s and dewpoints into the mid 60s! 70s are not record-breaking, but mid-60s dewpoints are remarkable for Feb. #CAwx

In addition, a weak cut-off low will entrain copious subtropical moisture (remnants from last week's atmospheric river) over NE Pacific & drag it inland across NorCal Sat and Sun. This will bring an extremely warm/muggy winter airmass--and along with it some thunderstorms! #CAwx

Exceptionally warm-to-hot late winter conditions expected across the Southwest through the weekend, peaking Fri and Sat. Numerous daily record highs (and record warm overnight minimums) will be set, along with some Feb monthly records possible. [Thread] #CAwx #AZwx #NVwx

Remarkable and widespread record warmth today across the Southwest. In fact, some locations in southern CA and southern AZ are not just breaking daily records, but also monthly February records--with current temperatures well into 90s and approaching 100F in some spots. #CAwx #AZwx

There has been an amazing outpouring of support for the National Center for Atmospheric Research (NCAR) amid its proposed dismantling from people, institutions, & companies all across the country. You, too, can help by sending feedback to NSF by Mar 13th: www.ametsoc.org/ams/...

Exceptionally warm-to-hot late winter conditions expected across the Southwest through the weekend, peaking Fri and Sat. Numerous daily record highs (and record warm overnight minimums) will be set, along with some Feb monthly records possible. [Thread] #CAwx #AZwx #NVwx

2/26/26 10:50am: As expected, the ~1.7" increase in snow water equivalent (SWE)* from this week's rain was temporary and exited through the bottom of the snowpack. In fact, the warm storm melted some of the snowpack, so we are now at 19" rather than the 19.7" at the end of last week's snowfall. 1/2

Update: it is, indeed, a broader outage that is being addressed!

In case anyone can see this: all my Bluesky posts starting late yesterday have been autodeleted or are invisible to most/all users. Not sure what's up, or whether this is a broader issue. But please know that I have not been deleting anything! 👀

There has been an amazing outpouring of support for the National Center for Atmospheric Research (NCAR) amid its proposed dismantling from people, institutions, & companies all across the country. You, too, can help by sending feedback to NSF by Mar 13th: www.ametsoc.org/ams/...

New February monthly record high temperature at Pueblo: 83 °F. Numerous locations in southeast Colorado had highs in the 80s today. #cowx

I would love to see us put our money where our mouths are and invest in the actual infrastructure and expertise needed to communicate science. Enough lip service — we need actual money, jobs, and bureaucracy to make a real go at this thing we claim is vital.

After a relatively brief colder & snowier interlude, we've re-entered a period that will be characterized by sustained anomalous warmth in U.S. West. Today, daily record high temperatures are again occurring across portions of Southern Rockies and interior SW. #CAwx #COwx

Several locations in Rhode Island appear to have exceeded the previous state 24-hour snowfall record, and Providence shattered their prior daily snowfall record by more than a foot. I tried to make an initial guess at why snowfall amounts may have been so insane: tinyurl.com/4296dshx

New on Weather West: If we're going to see an extremely moist & warm #AtmosphericRiver this wk in NorCal that will bring rain atop recent heavy snow, why is major flooding *not* expected? It a story of (lacking) storm dynamics & snowpack resilience. #CAwx

I have devoted much of my weather & climate career to engaging with journalists--including 200-300 news media interviews per year, many of which involve recurring conversations to facilitate timely & contextually accurate coverage. This recent collapse has been stunning and deeply disconcerting.

On Mon, Feb 23 at noon PT, I'll host a livestream discuss why upcoming extremely warm atmospheric river, which will bring warm rain atop snow, is only anticipated to bring modest flood risk. Plus: how much did recent storms bolster Western U.S. snowpack?

New on Weather West: If we're going to see an extremely moist & warm #AtmosphericRiver this wk in NorCal that will bring rain atop recent heavy snow, why is major flooding *not* expected? It a story of (lacking) storm dynamics & snowpack resilience. #CAwx

On Mon, Feb 23 at noon PT, I'll host a livestream discuss why upcoming extremely warm atmospheric river, which will bring warm rain atop snow, is only anticipated to bring modest flood risk. Plus: how much did recent storms bolster Western U.S. snowpack?

I have devoted much of my weather & climate career to engaging with journalists--including 200-300 news media interviews per year, many of which involve recurring conversations to facilitate timely & contextually accurate coverage. This recent collapse has been stunning and deeply disconcerting.

TL;DR: A warm & moist atmospheric river is headed for NorCal, and will cause a rain-on-snow event in mountain regions that recently saw huge snowfall. Some flooding likely, but more likely minor-moderate vs worse due to modest storm dynamics & ability of snowpack to absorb rain.

In areas with 3-5+ feet on the ground, it's likely that snowpack will absorb much if not most of this rain-on-snow. That's water that won't become runoff during the event, and won't contribute to flooding. However, some minor to moderate flood risk will still arise. Where?

The second mitigating factor is that rain falling into deep snowpack does not necessarily, despite popular belief, quickly melt it all. In fact, if snow is deep & cold enough, several inches of rain can actually be entirely absorbed by snowpack--raising its water content!

But...there will likely be (thankfully!) two major mitigating factors from flood risk perspective. The first and most important: overall rainfall accumulations look relatively moderate, not heavy. Rainfall rates will also be relatively gradual vs intense.

Well, snow levels in mountains will be *extremely* high: above 10,000-13,000 feet in Sierra (highest in south). It'll be essentially all rain in the mountains, even up on peaks/top of the chairlifts. Several inches of rain could, indeed, fall directly into the snowpack. But...

Following last week's heavy & disruptive Sierra Nevada snowfall, an extremely warm atmospheric river will cause substantial rain to fall atop snowpack even at high elevations this week. *However,* widespread serious flooding is *not* expected...for now. Why? [Thread] #CAwx

🚨🔥 NEW: Increasing mortality from wildfire smoke is directly traceable to greenhouse gas emissions. In our new paper in @pnas.org , we show that every megaton of CO2 emitted costs the US more than 10 million dollars in health costs from wildfire smoke. www.pnas.org/doi/10.1073/...

In case you missed this deep dive into the very heavy Sierra Nevada snowfall and its historical context, yesterday's deadly avalanche and severe thunderstorms in LA, and the potential for a warm atmospheric river this weekend, this session was recorded (view at link below). #CAwx

Federal officials now project that Lake Powell will "most probably" drop below power pool level — meaning Glen Canyon Dam will no longer be able to generate hydropower — before the end of this year: www.landdesk.org/p/the-colora... via @landdesk.bsky.social

This thread shows a deliberate defunding of U.S. science, engineering, social science, innovation, and education excellence. It’s a U.S. national security, competitiveness, and economic disaster.

In case you missed this deep dive into the very heavy Sierra Nevada snowfall and its historical context, yesterday's deadly avalanche and severe thunderstorms in LA, and the potential for a warm atmospheric river this weekend, this session was recorded (view at link below). #CAwx

Tune in TODAY (Feb. 18) at 2 pm. #CAwx @weatherwest.bsky.social

In the last twenty-four hours, a powerful winter storm has dropped between 1 to 3 feet of snow in Sierra Nevada. The heavy snow exacerbated conditions for dangerous avalanches, especially in the Lake Tahoe region where the heaviest snowfall occurred.

2/18/26 8:45 am Update: 1-day ❄️: 29.3" (74.5 cm) 2-day ❄️: 57.5" (146 cm) 3-day❄️ (storm total): 66.9" (170 cm) We have flurries and calm conditions currently but snowfall rates will pick up this afternoon and evening bringing another 2-3 feet by Friday morning. #CAwx #CAwater

I'll have a "late-breaking" livestream session tomorrow (Wed, Feb 18) at 2pm PT to discuss multiple topics, including: Recent switch to colder/wetter conditions (including news re: major avalanche) & updates re: EPA GHG regs & efforts to save NCAR. #CAwx

Climate change coverage fell 14% globally in 2025, while the world endured record heat, raging wildfires, and devastating floods. The crisis intensified. The headlines didn’t. Less coverage = less urgency. www.colorado.edu/today/2026/0...

I'll have a "late-breaking" livestream session tomorrow (Wed, Feb 18) at 2pm PT to discuss multiple topics, including: Recent switch to colder/wetter conditions (including news re: major avalanche) & updates re: EPA GHG regs & efforts to save NCAR. #CAwx