Wind speeds recorded in India during the Nor'wester 2013 Season.

 During the hot weather period i.e from March to May the eastern and North-eastern states of the subcontinent like West Bengal, Bihar, Assam, Orissa (parts) and Bangladesh experience dramatic appearance of a special type of violent thunderstorm know as Nor’wester. In Bengal it is known as ‘Kal Baisakhi’ or calamity of the month of Baisakh (April,15-May,15). Apart from its destructive effects like sudden rise in wind speed, lightning, thunder and hail the rainfall associated with the storm.

 For the occurrence of a nor’wester, the lower level moisture flow from the Bay of Bengal is essential. In the summer months the atmosphere becomes unstable due to intense insolation. On such days if there is a suitable synoptic situation such as a surface low pressure area over Jharkhand and adjoining districts of Gangetic West Bengal, the cyclonic vorticity reaching up to 1.5 kilometers above sea level with dry air aloft and presence of a jet stream between the levels 300 mb and 200 mb in the vicinity of Gangetic West Bengal are extremely helpful for the occurrence of nor’westers..

 Alipore is the king of Nor'wester in India in 2013

Min (50 km/hr) (From 1st April to 31st May, 2013)

1. Alipore, West Bengal - 116 km/hr on 17th April, 2013
2. Diamond Harbour, West Bengal - 116 km/hr on 17th April, 2013
3. Gaya, Bihar - 96 km/hr on 17th April, 2013
4. Tezpur, Assam - 93 km/hr on 3rd April, 2013
5. Guwahati, Assam - 80 km/hr on 14th April, 2013
6. Alipore, West Bengal - 76 km/hr on 12th May, 2013
7. Agartala, Tripura - 74 km/hr on 19th April, 2013
8. Bhubaneswar, Orissa - 72 km/hr on 26th May, 2013
9. Alipore, West Bengal - 72 km/hr on 19th May, 2013
10. Dum Dum, West Bengal - 68 km/hr on 17th April, 2013
11. Bankura, West Bengal - 65 km/hr on 19th May, 2013
12. Puri, Orissa - 64 km/hr on 21st April, 2013
13. Alipore, West Bengal - 63 km/hr on 11th April, 2013
14. Daltonganj, Jharkhand - 62 km/hr on 13th April, 2013
15. Dum Dum, West Bengal - 60 km/hr on 20th May, 2013
16. Alipore, West Bengal - 60 km/hr on 4th April, 2013
17. Alipore, West Bengal - 60 km/hr on 17th May, 2013
18. Patna, Bihar - 58 km/hr on 14th April, 2013
19. Paradeep, Orissa - 56 km/hr on 26th May, 2013 
20. Dum Dum, West Bengal - 56 km/hr on 17th May, 2013
21. Chandbali, Orissa - 56 km/hr on 7th May, 2013
22. Daltonganj, Jharkhand - 56 km/hr on 14th April, 2013
23. Daltonganj, Jharkhand - 56 km/hr on 2nd April, 2013
24. Alipore, West Bengal - 56 km/hr on 21st April, 2013
25. Alipore, West Bengal - 56 km/hr on 15th April, 2013
26. Chandbali, Orissa - 56 km/hr on 15th April, 2013
27. Digha, West Bengal - 55 km/hr on 19th April, 2013
28. Dum Dum, West Bengal - 52 km/hr on 19th May, 2013
29. Malda, West Bengal - 50 km/hr on 17th May, 2013

Nor'wester causes Assam boat mishap death toll may cross 200

Local authorities in western Assam's Dhubri town fear the death toll in Monday's boat mishap on river Brahmaputra may cross the 200 mark. The ill-fated double-decker boat had a carrying capacity of 250 passengers but reportedly had some 500 on board.

Taleb Ali, 42, who swam to safety and saved four others. said "There were at least 500 people on the boat, and I was lucky to have been on the upper deck. Most of the people were in the cage-like lower deck and I fear they were trapped. The death toll will cross 200," he said from Madhertari, nearest to the spot where the boat caught a cyclonic storm and "broke into three pieces".

"The mishap happened barely 50 metres from the bank, and local people beat the rescue teams to the bodies and took their kin's home possibly for the final rites." The boat had set sail from Dhubri town, 287km west of Guwahati on the northern bank of river Brahmaputra in the afternoon."It was heading southeast to Hatsinghimari, a three-hour trip".

Principal Secretary (Revenue and Disaster Management) V.K. Pipersenia, when contacted, said inland ferries in Assam were not equipped with any meteorological device and the entire system was old and traditional. “We will have to take up with the India Meteorological Department the matter of issuing advanced storm warnings on Norwesters to prevent such accidents.”

Eyewitnesses told police the vessel was old and broke in two after capsizing in the swollen river, one of Asia's largest.Hasnat Ali, a passenger, told local television that the boat was tossed about and many of those on the roof were thrown off and managed to swim to shore before the ferry was dashed to pieces.

I managed to cling to a log and was later rescued by local villagers, he said.

Nor'wester   

During the hot weather period i.e from March to May the eastern and North-eastern states of the subcontinent like West Bengal, Bihar, Assam, Orissa (parts) and Bangladesh experience dramatic appearance of a special type of violent thunderstorm know as Nor’wester.    

In the summer months the atmosphere becomes unstable due to intense insolation. On such days if there is a suitable synoptic situation such as a surface low pressure area over Jharkhand and adjoining districts of Gangetic West Bengal, the cyclonic vorticity reaching up to 1.5 kilometers above sea level with dry air aloft and presence of a jet stream between the levels 300 mb and 200 mb in the vicinity of Gangetic West Bengal are extremely helpful for the occurrence of nor’westers.. 

In Bengal it is known as ‘KalBaisakhi’ or calamity of the month of Baisakh (April,15-May,15). Apart from its destructive effects like sudden rise in wind speed, lightning, thunder  and hail the rainfall associated with the storm although small in amount, is extremely helpful for the pre-Kharif crops like jute, Aus paddy, summer till and a large number of vegetables and fruits and the sudden drop in temperature gives relief after unbearable mid-day heat.   

The dramatic appearance of nor’wester in the afternoon or evening of pre-monsoon months over Bengal, Bihar, Assam and adjoining areas has been a matter of great interest not only to the meteorologists but to all sections of people and has a bright existence in Bengali literature. Famous Bengali poet Mohit Lal Majumder described nor’wester so nicely in his poem “KalBaisakhi” that a meteorologist can hardly do. However, Nor’wester is subject of universal interest for a number of reasons. It not only gives relief after mid-day heat but pours well its crops. Its nature is unique and the causes are really interesting.