Highly localized, extreme rainfall in Kalimpong :01Aug2023

With a deep depression in the north Bay, 01Aug2023 started off in North Bengal and Kalimpong as a warm, dry day and remained so most of the day. There was little indication of the severe weather which was looming in the evening and IMD had issued only a YELLOW warning for our region.
The first patches of cumulonimbus clouds appeared in the satellite image at 5.45pm.

Thundershowers started around 6.30pm and continued nonstop till 11.30pm. Rainfall intensities remained high as can be seen from the graph.

What was very surprising was that the rainfall was very localized with the precipitation only occurring in Kalimpong. Other towns in the vicinity had the normal expected rain - only Jhalong and Rongo in the far east of Kalimpong district showed the extreme rain as was experienced in Kalimpong.

Even though landslides did occur, their prevalence was not high - perhaps because of the meagre rainfall received in north Bengal in the latter half of Jul2023 and the consequent decrease in the moisture content of the soil.

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

Extreme thunderstorm at Kalimpong (20Sep2019)

Photo credits : Ms Shreya Gurung

* Having worked on the landslide problem of this region, I am very worried when we have intense rainfall towards the end of the monsoons. Some of our major landslide events (Oct 1968, Sep2007) have taken place at this time when the soil is saturated in the months of monsoon rain and a heavy downpour occurs triggering slope failure.
Last evening, we were lucky - the rainfall was extreme and intense reaching 215mm/hr and staying over a 100mm/hr for a good 20mins. Maybe what saved us was:
a. The past 10days have seen deficient rainfall with the last 2 days being dry.
b. The storm quickly moved away from us and within an hour we were dry again.
* And this seems to be the new normal where we alternate between rainfall deficiencies and surplus, where we either have no water and our fields and springs are dry or when we have so much water that it causes landslides and death.
* Having said this, I would also like to bring to light the recent landslides in Tsong, Yuksom area of Sikkim where there was no warning of heavy rain in the area as in the case of Kalimpong yesterday. These small local weather events which can result in heavy downpours but do not show up on satellite imagery and therefore give no warning are increasingly the ones we must guard against.


Total rainfall in the thunderstorm on 20Sep2019 42.7mm



Praful Rao
Kalimpong district
Darjeeling-Sikkim Himalaya