1970 North Indian Ocean cyclone season

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1970 North Indian Ocean cyclone season
Season summary map
Seasonal boundaries
First system formedMay 2, 1970
Last system dissipatedNovember 29, 1970
Strongest storm
NameThirteen
 • Maximum winds185 km/h (115 mph)
 • Lowest pressure960 hPa (mbar)
Seasonal statistics
Depressions15
Deep depressions11
Cyclonic storms7
Severe cyclonic storms3
Total fatalities500,805+ (Deadliest tropical cyclone season on record)
Total damage$86.4 million (1970 USD)
Related articles
North Indian Ocean tropical cyclone seasons
1968, 1969, 1970, 1971, 1972

The 1970 North Indian Ocean cyclone season had no bounds, but tropical cyclones in the North Indian Ocean tend to form between April and December, with peaks in May and November. The 1970 season saw a total of seven cyclonic storms, of which three developed into severe cyclonic storms. The Bay of Bengal was more active than the Arabian Sea during 1970, with all of the three severe cyclonic storms in the season forming there. Unusually, none of the storms in the Arabian Sea made landfall this year. The most significant storm of the season was the Bhola cyclone, which formed in the Bay of Bengal and hit Bangladesh on November 12. The storm killed at least 500,000, making it the deadliest tropical cyclone in recorded history.[1] The season was also the deadliest tropical cyclone season globally, with 500,805 fatalities, mostly due to the aforementioned Bhola cyclone.

Season summary

1970 Bhola Cyclone

Systems

Severe Cyclonic Storm One

Very severe cyclonic storm (IMD)
 
DurationMay 2 – May 7
Peak intensity150 km/h (90 mph) (3-min);
975 hPa (mbar)

A low-pressure area that developed over the southern

Burma
that evening.

The cyclone brought widespread rain to the

Akyab in western Burma reported winds of 55 km/h (35 mph) as the cyclone approached land.[2]

Depression Two

Depression (IMD)
 
DurationMay 23 – May 24
Peak intensity45 km/h (30 mph) (3-min);

A depression formed in the northeast of the Bay of Bengal during the morning of May 23, near the East Pakistan coast. It moved towards the coast and made landfall to the south of Cox's Bazar that night, before dissipating over southern Assam on the next day.[2] Any effects on land are unknown.

Cyclonic Storm Three

Severe cyclonic storm (IMD)
 
DurationMay 28 – June 2
Peak intensity95 km/h (60 mph) (3-min);
986 hPa (mbar)

A low-pressure area developed off the Karnataka–Goa coastline in the Arabian Sea on May 27, and developed into a depression on the next day. The system developed further into a cyclonic storm on May 29 as it moved to the north. The storm reached its peak with 95 km/h (60 mph); soon after this, as it turned to the west, but soon degenerated into a deep depression over the northern Arabian Sea on May 31. The depression continued to move westward, weakening to a remnant low shortly afterward, as it made landfall on the Arabian Peninsula, on June 2. The remnant low dissipated over southern Saudi Arabia on the next day.[2] The cyclone itself had minimal effects on land, but the monsoon advanced into western India in late May in association with the system. As the cyclone moved to the west away from the subcontinent, the incursion of moist air from the Arabian Sea persisted over northwestern India for the first three days of June. This brought moderate rainfall to regions of Gujarat, Rajasthan and western Madhya Pradesh.[2]

Cyclonic Storm Four

Cyclonic storm (IMD)
 
DurationJune 7 – June 11
Peak intensity≥65 km/h (40 mph) (3-min);
986 hPa (mbar)

A low-pressure area developed in the northern Bay of Bengal on June 6 and developed into a depression on the next day, as it drifted to the north, moving over the south of the

Orissa that night. The cyclone quickly weakened to a deep depression overland and tracked to the west over central India, where it degenerated into a broad area of low pressure on June 11.[2]
Sustained winds of 65 km/h (40 mph) were recorded at Sandheads on June 9, while the cyclone was at its peak offshore. High levels of rain affected much of Orissa and West Bengal, with over 100 mm (3.9 in) falling over large areas of both states. As the storm dissipated overland, it brought severe rain to Vidarbha and southern Madhya Pradesh. The highest recorded rainfall was at Khandwa were 280 mm (11 in) fell on June 13 alone. The rains led to localised flooding in parts of Vidarbha and disrupted road transport in the region.[2]

Deep Depression Five

Deep depression (IMD)
 
DurationJune 29 – July 3
Peak intensity≥50 km/h (30 mph) (3-min);

A low-pressure area that had developed over the northern

Orissa coast. After landfall, the storm continued to move to the northwest, weakening to a depression again on July 2, over northeast Madhya Pradesh. It degenerated into a remnant low over central Uttar Pradesh during the evening of July 3.[2]
The depression brought intense monsoon conditions to Orissa, Madhya Pradesh and
Cuttack District. Further west, the Wainganga River overflowed its banks in places. Road transport in Madhya Pradesh was disrupted and there was damage to crops in the Raipur area. Raipur recorded the highest 24-hour rains associated with the depression, with 230 mm (9.1 in) falling there on July 2.[2]

Deep Depression Six

Deep depression (IMD)
 
DurationJuly 6 – July 8
Peak intensity55 km/h (35 mph) (3-min);
≤992 hPa (mbar)

A low-pressure area moved to the west, off the

Orissa coast during the morning of July 8, and rapidly degenerated into a broad area of low pressure overland. The remnant low moved north over western Bihar and it persisted there until July 12, when it was absorbed by the monsoon trough.[2]
Winds of 55 km/h (35 mph) were recorded offshore at Sandheads when the system was at its peak. The depression brought isolated heavy rains to many places throughout East India, with rains in excess of 100 mm (3.9 in) falling each day from the depression's landfall until the absorption of the storm's remnant low.[2]

Depression Seven

Depression (IMD)
 
DurationAugust 17 – August 19
Peak intensity45 km/h (30 mph) (3-min);

A low-pressure area that lay over

Gopalpur-on-Sea. The depression moved to the northwest and made landfall near Gopalpur-on-Sea, and turned to the west overland. The depression had weakened into a remnant low by August 20, when it was over western Madhya Pradesh.[2]
The depression and associated weather brought widespread rain to much of south and central India, with heavy rain falling in some locations. The heavy rain in
Bombay with 200 mm (7.9 in) falling there on August 19.[2]

Cyclonic Storm Eight

Cyclonic storm (IMD)
 
DurationSeptember 2 – September 13
Peak intensity65 km/h (40 mph) (3-min);

A low-pressure area that was centred over West Bengal on August 31 organized into a depression on September 2, when it was 50 km (31 mi) to the east of Midnapore. It intensified as it moved to the west, becoming a deep depression on the next day, about 50 km (31 mi) east of Ranchi. The system continued to move west across India, before weakening into a depression on September 7, near Ahmedabad, Gujarat. The depression then turned northward and entered southwest Rajasthan.[2] On September 8, the system turned to the southwest and emerged into the Arabian Sea on the following evening. Over open water, it intensified again, becoming a cyclonic storm by the evening of September 10. The cyclone developed a short-lived eye on September 11, as it drifted slowly to the west, before degenerating into a broad area of low pressure as it neared the Oman coast, on September 14.[2] This system brought widespread rains to a wide swathe of India during its existence. Some heavy rains in West Bengal flooded vast areas of many districts and resulted in some fatalities, whilst in parts of neighbouring

Kutch District as the cyclone moved out to sea.[2]

Deep Depression Nine

Deep depression (IMD)
 
DurationSeptember 8 – September 18
Peak intensity55 km/h (35 mph) (3-min);
990 hPa (mbar)

A low-pressure area moved from

Calcutta. The system crossed the West Bengal coast later and moved to the northwest across the Chota Nagpur Plateau. The depression stalled over Uttar Pradesh on September 12, and remained near Lucknow until September 14. The depression then turned to the east and weakened into a remnant low over northern Bihar, on September 18.[2]
The depression brought widespread rain to West Bengal,
Munger District, whilst the Gandaki River flooded parts of Motihari. The rains worsened floods in south Bengal, increasing the death toll from the floods there to 80 and affecting 8 million people, with considerable damage done to crops and housing. Jaleswar in Orissa was entirely flooded.[2]

Depression Ten

Depression (IMD)
 
DurationSeptember 21 – September 23
Peak intensity45 km/h (30 mph) (3-min);

A well-defined low-pressure area formed over the west central Bay of Bengal on September 20, and developed into a depression on the next morning about 100 km (62 mi) south-east of Visakhapatnam. The depression then moved overland, and after crossing Vidarbha, weakened into a remnant low over Gujarat on September 23.[2] The depression brought widespread rain to northern

Bombay as the system dissipated. The heavy rains claimed about 75 lives.[2]

Depression Eleven

Depression (IMD)
 
DurationOctober 11 – October 13
Peak intensity45 km/h (30 mph) (3-min);

A low-pressure area that developed in the Bay of Bengal passed over the southern

Laccadives.[2]

Severe Cyclonic Storm Twelve

Very severe cyclonic storm (IMD)
 
DurationOctober 18 – October 24
Peak intensity130 km/h (80 mph) (3-min);
980 hPa (mbar)

A depression formed on October 18 in the central Bay of Bengal, and moved to the north. It gradually intensified and turned to the northeast, becoming a cyclonic storm on October 20. The storm became the second severe cyclonic storm of the season on the following day, and turned onto a more northerly track towards the Ganges Delta. The storm peaked with winds of 130 km/h (80 mph) before it made landfall near the West Bengal–East Pakistan border, during the morning of October 23. The storm then crossed over East Pakistan, before dissipating over southern Assam on October 24.[2]

This cyclone brought widespread rain to

Calcutta as the storm passed by to the east, where it caused the failure of the power supply.[2]

The cyclone claimed between 200 and 300 lives in East Pakistan, with the worst of the damage occurring in Khulna District.[2] Over 200 villages were destroyed in the district, leaving several thousand people homeless, and there was extensive damage to crops.[3]

Extremely Severe Cyclonic Storm Thirteen

Extremely severe cyclonic storm (IMD)
Category 4 tropical cyclone (SSHWS)
 
DurationNovember 8 – November 13
Peak intensity185 km/h (115 mph) (3-min);
960 hPa (mbar)
Main article: 1970 Bhola cyclone

On the morning of November 8, a depression formed in the south-central Bay of Bengal. It moved very slowly to the north, becoming a cyclonic storm on the next day. The cyclone continued to intensify as it approached the head of the Bay, becoming the third severe cyclonic storm of the season on November 11. That evening, it reached its peak intensity, with winds of 185 km/h (115 mph) with a well-developed eye, becoming the strongest storm of the season. On November 11 the Indian 5500 tonne freighter the Mahajagmitra reported wind speeds of 180 miles an hour and relayed a distress signal before it sank off the East Coast of India with 50 people on board.[4] The vortex then made landfall on the coast of East Pakistan during the night of November 12. The cyclone weakened rapidly as it moved inland and dissipated on the next day, over south Assam.[2]

This cyclone brought a devastating storm surge of up to 10 metres (33 feet) high to the Ganges Delta. Largely as a result of this surge, somewhere between 300,000 and 500,000 people lost their lives, making this storm the deadliest tropical cyclone ever recorded and one of the deadliest natural disasters of modern times.[1][5] The total damage from the storm exceeded $85 million (1970 USD, $480 million 2008 USD), and much of the agricultural and fishing capacity of the region was wiped out. A total of some 3.6 million people suffered direct effects from this cyclone.[6]

The Pakistani government was severely criticized for its handling of the relief operations following the storm, both by local political leaders in East Pakistan and in the international media. In the December national elections, the opposition Awami League gained a landslide victory, gaining 160 of the 162 East Pakistani seats. Continuing unrest between East Pakistanis and the central government trigged the Bangladesh Liberation War, which concluded with the creation of the state of Bangladesh. This is one of the first times that a natural event helped to trigger a civil war in the modern era.[7]

Deep Depression Fourteen

Deep depression (IMD)
 
DurationNovember 19 – November 20
Peak intensity≥50 km/h (30 mph) (3-min);

A low-pressure are that had developed over the south

Madras. The system intensified further into a deep depression, as it moved west-northwestward, and made landfall on Tamil Nadu on the following day. The depression subsequently weakened into a remnant low over Tamil Nadu.[2]
The depression brought widespread rain to much of Tamil Nadu, with heavy rain impacting the coastal regions. Low-lying coastal regions from
Thanjavur District and the rains left thousands homeless in Madras. Cuddalore experienced exceptionally heavy rains with over 440 mm (17 in) falling there, of which 310 mm (12 in) fell on November 20 alone.[2]

Cyclonic Storm Fifteen

Cyclonic storm (IMD)
 
DurationNovember 22 – November 29
Peak intensity75 km/h (45 mph) (3-min);

The remnant low of a depression emerged into the Arabian Sea off Kerala late on November 21, and developed into a new depression on the next day, as it moved westward. The depression moved further west, and gradually turned toward the southwest, intensifying as it did so. It became a cyclonic storm on November 28, to the southeast of Socotra, and reached its peak intensity with winds of 75 km/h (45 mph) soon after. The cyclone continued to move west-southwestward, and rapidly weakened into a remnant low-pressure area off the Somalia coast on the next day, ending the season.[2] The cyclone brought widespread rain to the

Laccadives from November 22 to 24, with 60 mm (2.4 in) recorded on Amini on November 23.[2]

Season effects

This is a table of all storms in the 1970 North Indian Ocean cyclone season. It mentions all of the season's storms and their names, durations, peak intensities (according to the IMD storm scale), areas affected, damages, and death totals. Damage and death totals include the damage and deaths caused when that storm was a precursor wave or extratropical low, and all of the damage figures are in 1970 USD.

Name Dates Peak intensity Areas affected Damage
(USD) 		Deaths Refs
Category Wind speed Pressure
One May 2–7, 1970 Very severe cyclonic storm 150 km/h (95 mph) 975 hPa (28.79 inHg) Bangladesh, Myanmar [2]
Two May 23–24, 1970 Depression Not specified Not specified Bangladesh, Myanmar [2]
Three May 28 – June 2, 1970 Severe Cyclonic Storm 95 km/h (60 mph) 986 hPa (29.12 inHg) Saudi Arabia [2]
Four June 7–8, 1970 Cyclonic Storm 65 km/h (40 mph) 982 hPa (29.00 inHg) West Bengal, Orissa, Madhya Pradesh [2]
Five June 29 – July 3, 1970 Deep Depression Not specified Not specified Orissa [2]
Six July 6–8, 1970 Deep Depression Not specified Not specified Burma, Orissa [2]
Seven August 17–19, 1970 Deep Depression Not specified Not specified Burma, Orissa [2]
Eight September 2–13, 1970 Cyclonic Storm Not specified Not specified West Bengal, Orissa, Coastal Arabia [2]
Nine September 8–18, 1970 Deep Depression Not specified Not specified Burma, West Bengsl [2]
Ten September 21–23, 1970 Depression Not specified Not specified Andra Pradesh [2]
Eleven October 11–13, 1970 Depression Not specified Not specified Saudi Arabia [2]
Twelve October 18–22, 1970 Very Severe Cyclonic Storm 130 km/h (80 mph) 980 hPa (28.94 inHg) Tamil Nadu, West Bengal, Bangladesh 200-300 [2]
Thirteen November 8–13, 1970 Extremely Severe Cyclonic Storm 185 km/h (115 mph) 966 hPa (28.53 inHg) India, Bangladesh 300,000–500,000 [2]
Fourteen November 19–20, 1970 Deep Depression Not specified Not specified Tamil Nadu [2]
Fifteen November 22–29, 1970 Cyclonic Storm 75 km/h (45 mph) Not specified Somalia [2]
Season aggregates
15 systems May 2 – November 29, 1970 150 km/h (95 mph) 975 hPa (28.79 inHg) Unknown ≥302,000

See also

References

  1. ^ a b The world's worst natural disasters Calamities of the 20th and 21st centuries CBC News. Retrieved 2010-10-29.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar India Weather Review Annual Summary — Part-C: Storms and Depressions 1970 (PDF) (Report). India Meteorological Department. 1971. Archived from the original (PDF) on June 14, 2019. Retrieved May 26, 2020.
  3. ^ Staff writer (October 27, 1970). "125 Die In Hurricane In Pakistan" (PDF). The Daily Gleaner. Reuters. Retrieved April 15, 2007.[dead link]
  4. ^ SAARC ftp://rammftp.cira.colostate.edu/ftpguest/SAARC_report.doc
  5. ^ Kabir, M. M.; Saha B. C.; Hye, J. M. A. "Cyclonic Storm Surge Modelling for Design of Coastal Polder" (PDF). Institute of Water Modeling. Archived from the original (PDF) on June 22, 2007. Retrieved April 15, 2007.
  6. ^ Centre for Research on the Epidemiology of Disasters. "EM-DAT: The Emergency Events Database". Université catholique de Louvain.
  7. USAID. Archived from the original
    (PDF) on September 19, 2009. Retrieved April 15, 2007.
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