The mechanics of the Nepali flash flood

I think they have their fair share of snow storms during the winter because of the vortex coming from the West. The vortex goes down from Alaska because the mountains block it, and then it turns east and goes straight to the lake area.

I live in Montreal, but sometimes I see bitter weathers in Toronto during the winter. Ofc we have our share of pain, but I'm fine with snow -- raining is a huge problem in recent years -- I'm installing a French Drain right now, and hopefully it offers enough protection. However, my house is sitting on top of clay, so that could be a big issue.

Thanks, I see that Lahars are technically associated with volcanoes as another comment noted. They have a variety of causes of which glacial collapse is one. [0] The term jökulhlaup describes a flood originating from a glacier, for example draining of a glacial lake. [1] It now seems the Nepali flood was triggered by a landslide onto a glacier.

As a practical matter the effects are pretty similar. Rainier has had lahars and jökulhlaups in the past.

[0] https://en.wikipedia.org/wiki/Lahar

[1] https://en.wikipedia.org/wiki/J%C3%B6kulhlaup

Snow can be annoying but is rarely catastrophic.

Somewhat more concerning is that tornado frequency is increasing at a ferocious rate, though most are relatively minor (EF-0 / EF-1).

The total for 2026 to date is 207 ground tracks (as of 27 Aug 2026). The previous full year record was 142, and the historical average (again full-year) is closer to 50.

This has knock-on effects to insurance as well as raising home and landscaping repair (downed trees, etc.).

https://chicago.suntimes.com/environment/2026/08/27/200-torn...>

Flash-flooding is also an increasing concern, though unlike Nepal, water channels tend to be largely flat. Urban creeks, local rivers, retention ponds, and low-lying locations (underpasses, local low spots) may experience flooding, though generally flow strength is low. Basement flooding is the most likely risk.

The same argument could have been made about wildfire deaths and damage through the early 2000s in the US.

It turns out that improved forecasting, warning systems, and well-established emergency response, rescue, and recovery systems, can all tamp down risk.

Looking at your article, the subhead reveals a split narrative: "Natural disasters may cost more money, but they claim far fewer lives than in decades past."

What's begun to occur with wildfires is that events are now exceeding the capability of even advanced modern technological societies to address them. Wildfires now regularly enter the urban core, not merely the urban fringe. That's something unheard of in the US from roughly the 1920s, and there wasn't a notable large-scale urban fire until the Oakland Hills firestorm of 1991. Even that was arguably at the wildland-urban interface (WUI). Contrast the Tea Fire (2008, Montecito & Santa Barbara, CA), the Tubbs Fire (2017, Santa Rosa and Sonoma, CA), Camp Fire (2018, Paradise, CA), Carr Fire (2018, Redding, CA), the August 2020 California lightning fires (2020, multiple locations, 3,500+ structures destroyed), the Marshall fire (2021, Marshall, Superior, and Louisvill, CO), the Mountain Fire (2024, Ventura, CA), the Hawaii wildfires (2023, Lahaina, HI), the 2025 Los Angeles wildfires (2025, Pasadena and Altadena CA amongst other locations), and the 2026 Spokane complex (2025, Spokane, WA, ~850 structures).

That's just within the US (an advanced modern technological society), omits wildfires not significantly impacting urban regions, and probably skips a few. There've also been unprecedented urban fires in Canada, Europe, and Australia within the past few decades after nearly a century of no such instances.

(Europe is an exception: for some reason there were numerous urban conflagrations in the period 1939--1945, e.g., Dresden and Hamburg, though climate doesn't seem directly implicated as I recall. Tokyo, Hiroshima, Nagasaki and other Japanese cities had a similar experience at the time.)

As more facts come out about the Nepal-Tibet glacial flood event of 2026, it's pretty clear that many casualties and damage were unavoidable at all once the event itself was triggered. Avoiding casualties would have required extensive evacuations of a nearly 100km stretch of the Trishuli River, possibly for weeks, with an affected population of over 1 million souls.

I've addressed this in a few recent HN comments: https://news.ycombinator.com/item?id=49473419> https://news.ycombinator.com/item?id=49473201> https://news.ycombinator.com/item?id=49460081>

No, it is not.

The camera position is elevated at least 6--8 stories above the valley floor, an elevation of 20--24m or so by my estimate.

Slightly below it is a concrete platform supporting a parabolic dish antenna.

That platform is well above the main debris flow, catches only comparatively minor impacts, and ... is knocked flat just before the video terminates.

More significantly, the three story block structure at the lower left of the frame is seen visibly displaced an instant before it is obscured by the debris flow, at about 30s into the video.

https://en.wikipedia.org/wiki/File:Mudslide_at_Gyirong_Port_...>

We now have before/after images of the precise location of the port. THere is absolutely no indicate that structures ever existed there:

https://news.cgtn.com/news/2026-08-28/3D-imagery-reveals-pat...>

From: "How do newly released 3D images explain the Gyirong mudslide?" https://news.cgtn.com/news/2026-08-28/3D-imagery-reveals-pat...>.

There is no conceivable way that this can be perceived as a minor or generally-survivable incident.