Great Sitkin (ORANGE/WATCH): What we've in-the-past called a MIR plume, or just a volcanic-disturbance plume, was visible all night from Great Sitkin. As recall, we've seen these most during the shoulder seasons (from Semisopochnoi, Great Sitkin, etc). It's very clear in overnight MIR, as well as in the RGB products in GOES-18. My recollection is that this is really just an effect of warm volcanic emissions/surface heating the overlying air and extending downwind a long ways, so it's an indication of activity (e.g., not present at Semi, Atka, Cleveland, etc), but not necessarily a change at the volcano, but just a change in the atmosphere. The same feature is present (morphologically) during the day (sentinel-2 image), but doesn't spectrally stand out. Otherwise no activity seen in cloudy views.

Associated Images:
375mAKKN-MIR-d20251122t1313986881Z-annotated.png
cira-rammb-slider---goes-18---full_disk---eumetsat_ash-opacity-100---20251122145022.png
2025-11-21-00_00_2025-11-21-23_59_Sentinel-2_L1C_True_color.jpg

Associated Keywords:
Volcanic clouds: ambiguous;
Cloud cover: cloudy;

Shishaldin (YELLOW/ADVISORY): No activity observed in mostly cloudy satellite and webcam views. The clouds hugged the edifice all day, so anything significant would've become visible, though (no SWIR signal in ~partly cloudy sentinel-2). Hard to delineate the steam but I think there's a little puffiness in there within the cloudcover.

Associated Images:
shishaldin_brpk-20251121T223200Z.jpg
2025-11-21-00_00_2025-11-21-23_59_Sentinel-2_L1C_Highlight_Optimized_Natural_Color.jpg

Associated Keywords:
Volcanic clouds: steam/water;
Cloud cover: cloudy; partly cloudy;