Was there a cloud burst in Sikkim on 03Oct2023?

The media is howling about a cloud burst that occurred in North Sikkim around the 03Oct2023 and which triggered the GLOF (Glacial Lake Outburst Flood) at South Lhonak lake, which led to the terrifying devastation in Sikkim and Kalimpong district on 04Oct 2023.

To get to the truth of the matter let us first see what is a cloud burst:
As per IMD
'If 100mm rainfall is received at a station in one hour, the rain event is termed as cloud burst.'

Placed below is a map and the rainfall data of North Sikkim (and Gangtok) and of Darjeeling and Kalimpong for the period 01Oct to 04Oct2023.

What is apparent is that Darjeeling and Kalimpong received far more rain than North Sikkim during this period and to support this are placed the Infra Red cloud images of 03Oct2023. Sikkim

It is highly unlikely that the type of clouding seen in the vicinity of Lhonak glacier would trigger a cloud burst since such high intensity rain is normally associated with convective clouding and cumulonimbus (CB) clouds which generate a distinct white signature in IR satellite images.
What are cumulonimbus (CB) clouds and how do they appear on IR satellite images?

How CB clouds appear on satellite imagery

There is no doubt that a GLOF did occur at South Lhonak glacier on 03/04Oct2023 between midnight and around 1am on 04Oct2023 - satellite imagery and reports from people at Lachen confirm this.
However, the widely held belief that a cloudburst triggered the GLOF is probably incorrect and maybe ascribed to media loosely calling any 'heavy rain' event a 'cloud burst' just as many issues these days are conveniently labelled under the banner 'climate change' without any verification.

So if a cloudburst did not trigger the GLOF, just what did?

That is a question which has still not been answered.

Praful Rao
Kalimpong district
Darjeeling-Sikkim Himalaya
savethehills@gmail.com
9475033744