Landslides associated with rapid snowmelt in western North America in May 2023

Guest post by loyal reader Funkenbeachin

The NASA map below shows the difference in air temperature between 15 May 2023 and the 2014-2022 mean for the same date. The map, derived from the Goddard Earth Observing System (GEOS) model, depicts air temperatures at 2 metres above the ground. Dark red areas are where air temperatures reached more than 22°F (12°C) above the recent average:-

Thermal anomalies for 15 May 2023 compared with the long term average for the same date. Image from NASA GEOS.

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A pattern of landslides associated with the resultant snowmelt is emerging.  For example, the 14 May 2023 debris flow at Johnston Ridge Observatory Access Road, Mount Saint Helens is associated with the thermal anomaly.

Loyal reader Drew commented that the same unseasonably warm weather, and resultant snowmelt also triggered a long runout landslide from Mount Job [50.633514, -123.547214] in the Meager Volcanic Complex in British Columbia, on 12 May 2023. This landslide can seen on Sentinel-2 satellite imagery.

The 12 May 2023 landslide from Mount Job in the Meager Volcanic Complex in British Columbia, Canada as shown on Sentinel-2 imagery.

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The NOHRSC Equivalent Snow Water model and NOHRSC station data near the slide depict rapid snowmelt associated with the landside.

Yet another snow melt related landslide appears to have occurred on Mount Shasta in California [41.434027, -122.211978] on 12 May 2023, and can be seen in Sentinel-2 imagery:-

The 12 May 2023 landslide on Mount Shasta, as seen in Sentinel-2 imagery.

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The NOHRSC Equivalent Snow Water model on 15 May 2023and NOHRSC station data from the Mount Shasta snow course station data for 1-30 May 2023 depict rapid snowmelt associated with the landside.