Rainfall data of September 2023 of some towns in the Darjeeling - Sikkim Himalaya

Technically the 'SW Monsoon season' in the country is deemed over on 30September, with October ushering in the 'Post Monsoon season'.

A number of low pressure areas formed in the Bay of Bengal in Sep2023, some being remnants of storms in the Pacific which intensified in the warm waters of the Bay. These systems undoubtedly impacted the rainfall pattern over our region.

The district-wise rainfall distribution for the period 01Jun to 27Sep2023  for Sikkim and Sub-Himalayan West Bengal (SHWB) ie for approx the entire monsoon season is given below:

See below a media report on rainfall during the monsoon season in the country:

September 2023 rainfall

The map below clearly indicates that in Sep2023, the hills towns of Darjeeling, Kalimpong districts and those in Sikkim received less rain than the towns in the plains and the really heavy rain was reserved for the foothills of Kalimpong and the Dooars plains.

Landslides
Landslides did occur in Sep2023; the most important one which occurred on NH10, at Sethi Jhora on 23Sep2023 has been covered in the previous blog. Information on other landslides will be posted as updates to this blog.

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

Rainfall data of Sep 2022 of some town in the Darjeeling - Sikkim Himalaya

 

We had deficient rainfall again for most towns with the notable exception of Mangan in N Sikkim.
Kalimpong was the most deficient receiving only 35% of its monthly rainfall. Interestingly, much of Kalimpong district is bang opposite SOUTH SIKKIM district and is separated only by the Teesta river. South Sikkim is the drought prone district of Sikkim ( -21% deficiency) as such rainfall deficiency in Kalimpong may be expected.
A number of low pressure areas formed in the Bay of Bengal during Sep2022 and that could be the reason for less rain in our region (the moisture bearing winds are drawn away from the sub - Himalayas when a circulation forms in the Bay).

Update from 'The Weather Channel' on 11Oct2022
Meanwhile, the southwest monsoon continues to withdraw from the northwestern parts of the country. Normally, its exit from the northeastern region begins around October 10; but judging from the rate of withdrawal thus far, it may get slightly delayed this year.

As for the seasonal precipitation, the northeastern region collectively recorded below-average rainfall during the four monsoon months from June to September. The combined monsoon rain figure for East and Northeast India stands at 1124.8 mm — 18% below their long-period monsoon average of 1367.3 mm.

Within the Northeast, the Assam-Meghalaya subdivision recorded 1600.7 mm rain (9% deficit), the N.M.M.T. states registered 943.2 mm precipitation (28% deficit), Arunachal Pradesh received 1430.3 mm (15% deficit), while Sub-Himalayan West Bengal and Sikkim enjoyed precisely ‘normal’ seasonal rains at 1887.1 mm.

Praful Rao
Kalimpong district
Darjeeling Sikkim Himalaya

Rainfall data of August 2022 of some town in the Darjeeling - Sikkim Himalaya

 

August 2022  was again a month when rainfall for most places, in the Darjeeling Sikkim Himalayas was less than normal - with most of the precipitation taking place in the plains of the Dooars in Jalpaiguri and Cooch Behar districts.
Also for the second successive month, Darjeeling had less rain than Kalimpong.

What undoubtedly caused less rainfall was sudden activity in the Bay of Bengal with several low pressure areas forming which then moved inland as depressions.

The rainfall distribution in Sikkim and North Bengal (as per IMD) is shown below. The hills of Darjeeling and Kalimpong districts along with East and South Sikkim districts saw deficient rainfall.

Not much landslide activity was observed in our region, the exception being several areas along NH10 (Highway connecting Siliguri to Gangtok).

As you would observe we have added several remote areas, in our rainfall reports - these area Mangzing and Bijanbari.
Mangzing (in Gorubathan block, Kalimpong district) receives the full fury of the monsoons and has the around the highest rainfall in our region.


Praful Rao,
Kalimpong district
Darjeeling - Sikkim Himalaya

At last, some signs of activity in the Northern Arabian Sea and the Pacific Ocean (27Jun2022)

When queried, a senior meteorologist had this explanation:

                            Deep trough in upper troposphere at 18Z/22Jun2022👆
This is La Nina year. When Equatorial Pacific will be unusually cool and equatorial Indian Ocean will be warm to give rise to good monsoon.
Lows help transporting energy from lower latitude to higher latitude. Currently the deep troughs associated with Western Disturbances is doing the job. In this low zonal Index phase chances of low formation will be less but deep trough activity will be more.

Update on 28Jun2022
JTWC had yesterday issued an ORANGE warning on storm 94A in the North Arabian sea which meant that it was likely to develop into a cyclone. Today, they have removed 94A altogether as such the entire northern Indian Ocean remains placid and calm - no low, depression or cyclone likely to form.

 

Praful Rao
Kalimpong district
Darjeeling Sikkim Himalaya