Great Sitkin (ORANGE/WATCH): Slightly elevated surface temperatures detected in NOAA-21 VIIRS MIR image from 10 Dec 2025 13:48 UTC (attached) and in Suomi VIIRS MIR image from 10 Dec 2025 14:17 UTC.

Associated Images:
375mAKKN-MIR-d20251210t1348096202Z.png

Associated Keywords:
Elevated surface temperatures: barely elevated;
Cloud cover: cloudy; partly cloudy;

Shishaldin (YELLOW/ADVISORY): Diffuse vapor plume evident in NOAA-21 VIIRS true color image from 9 Dec 2025 22:21 UTC (attached). Clear web camera views from yesterday showed a vapor plume at the summit. Possible SO2 emissions observed in VIIRS data from 9 Dec 2025 22:51 UTC (attached).

Associated Images:
375mAKSH-VIS-d20251209t2221973111Z.png
SO2-VIIRS-2025_12_09_225154-Eastern Aleutians.png

Associated Keywords:
Volcanic clouds: SO2 signal;
Cloud cover: mostly clear;