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https://doi.org/10.5194/egusphere-2026-5200
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-5200
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
09 Sep 2026
| 09 Sep 2026
Status: this preprint is open for discussion and under review for The Cryosphere (TC).
Brief communication: Unprecedented Everest storm reshapes expectations of future Himalayan precipitation extremes
Abstract. One of the most extreme snowstorms ever documented, with among the highest 12- and 24-hour liquid-equivalent accumulations recorded globally, was captured by an ultra-high-elevation weather-station network on Mt. Everest on 4 October 2025. Beyond redefining expectations of extreme Himalayan snowfall magnitudes, the event revealed a relationship between precipitation intensity and phase: melting of precipitating hydrometeors cooled the atmosphere and suppressed rain at glacierised elevations, with the low-density, high-altitude atmosphere amplifying this feedback. As the climate warms, more extreme Himalayan precipitation is likely, but whether such events bring rain or snow—and therefore their impacts—will depend on fine-scale storm dynamics.
How to cite. Matthews, T., Perry, B., Graves, B., Brun, F., Sanolaria-Otin, M., Pokhrel, N., Khadka, A., Shrestha, D., Cano, L., Kwadijk, A., Immereel, W., Maxwell, B., and Seimon, A.: Brief communication: Unprecedented Everest storm reshapes expectations of future Himalayan precipitation extremes, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-5200, 2026.
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Department of Geography, King’s College London, London, UK
Baker Perry
Department of Geography (Climatology), University of Nevada, Reno, Nevada, USA
Ben Graves
Department of Geography, King’s College London, London, UK
Fanny Brun
Institut des Géosciences de l’Environnement, Université Grenoble-Alpes, CNRS, IRD, Grenoble, France
Maria Sanolaria-Otin
Institut des Géosciences de l’Environnement, Université Grenoble-Alpes, CNRS, IRD, Grenoble, France
Navaraj Pokhrel
Department of Geography (Climatology), University of Nevada, Reno, Nevada, USA
Arbindra Khadka
Central Department of Hydrology and Meteorology, Tribhuvan University, Kirtipur, Nepal
Dibas Shrestha
Central Department of Hydrology and Meteorology, Tribhuvan University, Kirtipur, Nepal
Ludving Cano
Department of Geography (Climatology), University of Nevada, Reno, Nevada, USA
Aris Kwadijk
Department of Physical Geography, Utrecht University, Utrecht, The Netherlands
Walter Immereel
Department of Physical Geography, Utrecht University, Utrecht, The Netherlands
Brandt Maxwell
Brandt Maxwell Consulting, San Diego, California, USA
Anton Seimon
Bard College, Annandale-on-Hudson, New York State, USA
Short summary
Extreme precipitation shapes hazards and water resources in high mountains, but is rarely observed directly. On 4 October 2025, weather stations on Mt. Everest recorded one of the most extreme snowfall events ever measured. The storm revealed that Himalayan snowfall extremes can be far larger than previously documented, and that intense snowfall can cool the atmosphere sufficiently to prevent rain at impact-sensitive elevations, complicating the picture of how warming will affect future storms.
Extreme precipitation shapes hazards and water resources in high mountains, but is rarely...
“Temperature, and humidity data from up to eight AWSs in the Khumbu region of Nepal, in addition to two AWSs in the Langtang region”
Please state the exact number of stations used rather than “up to.”
“Fig. 2”
This figure is somewhat difficult to interpret, particularly the wind directions.
“Beyond redefining expectations of extreme Himalayan snowfall magnitudes....”
This is clearly an extreme event by any measure but the 'redefining expectations' claim needs some additional context. Is there indirect evidence of comparable precipitation extremes in the Himalaya? I recognize that precipitation gauges are sparse or non-existent. However, reports of snowfall on the ground may be more common. These are usually given as depth of snowfall. which can be converted to liquid equivalent under some assumptions about snow density or at least give a probabilistic estimate of liquid equivalent. Such reports could give a rough sense of the magnitude of extremes that were previously 'expected'.
More pressingly, Figure 2 shows data from the 0.1° MSWEP product, with rates of up to ~7 mm/hr. That is roughly consistent with the extreme 24-hr accumulations you report. Why not examine the 12- and 24-hr historical distributions of precipitation intensity from MSWEP, or, for that matter, from ERA5, ERA5-Land, IMERG, etc.? These products may not be well suited to mountainous terrain in this environment. But even so, demonstrating that is necessary to support the claim that this event “redefines expectations of extreme Himalayan snowfall.”
“3.4 Sensitivity of precipitation phase to warming”
The assumptions of this model are difficult to follow. The model appears to make two assumptions about a warmer storyline:
However, the depth of the isothermal layer may not be the sole determinant of precipitation phase. Humidity, in addition to dry-bulb temperature, affects the phase of precipitation reaching the ground. Presumably the layer is saturated. Other factors may also matter, such as the distance between cloud base and the surface, as well as hydrometeor fall speeds that are not be accounted for in this model. Also, the authors should explain explicitly how the increase in the thickness of the isothermal layer due to density effects influences rain/snow partitioning from the energy-balance perspective of a falling hydrometeor.
“This simple scaling therefore suggests that precipitation phase, during very extreme events, could remain considerably less sensitive to background warming over a substantial fraction of the region’s glaciers than implied by the present-day proximity to melting thresholds.”
It is not clear what “proximity to melting thresholds” refers to. Together with my previous comment, the authors should cite additional modeling work on rain/snow partitioning under warming to support these claims and show that this highly simplistic model is appropriate for thinking about the effects of warming on rain vs. snow in Himalayan glaciers.