| IMD Tropical Cyclone|
|Category||Wind speed (3-min)|
|Depression|| ≤27 |
|Deep Depression|| 28–33 |
|Cyclonic Storm|| 34–47 |
| Severe Cyclonic|
| Very Severe|
| 64–119 |
|Super Cyclonic Storm|| ≥120 |
The 2007 North Indian Ocean cyclone season was an event in the annual cycle of tropical cyclone formation. The North Indian Ocean cyclone season has no official bounds, but cyclones tend to form between April and December, with peaks in May and November. These dates conventionally delimit the period of each year when most tropical cyclones form in the northern Indian Ocean.
The scope of this article is limited to the Indian Ocean in the Northern Hemisphere, east of the Horn of Africa and west of the Malay Peninsula. There are two main seas in the North Indian Ocean - the Arabian Sea to the west of the Indian subcontinent, abbreviated ARB by the India Meteorological Department (IMD); and the Bay of Bengal to the east, abbreviated BOB by the IMD.
The official Regional Specialized Meteorological Centre in this basin is the India Meteorological Department (IMD), while the Joint Typhoon Warning Center releases unofficial advisories. The tropical cyclone scale for this basin is detailed on the right. On average, 4 to 6 storms form in this basin every season.
2007 was a busy year for this basin; it was the most destructive season in known history at this time, only for the 2008 season to surpass it the next year. 2007 was the first season to have multiple Category 5 cyclones (by the Saffir Simpson Scale), and the two Category 5s, Sidr and Gonu, were also the first named Category 5 cyclones to form in their respective seas; Gonu in the Arabian Sea, and Sidr in the Bay of Bengal. At least 4,545 deaths were reported, and damage is about 6.4 billion dollars.
The TMD issued heavy rain and flash flood warnings for western provinces during the system's passage over the Isthmus of Kra. In Ratchaburi Province, disaster response teams prepared for the evacuation of settlements in mountaineous terrain on May 3. The next day, Prachuap Khiri Khan Province was declared a disaster zone after low-lying areas were flooded with waters up to one metre deep. In the capital municipality, a prison was inundated, necessitating the evacuation of prisoners to Ratchaburi. In addition, a portion of rail was flooded, but train services were not disrupted. In Surat Thani Province, mudslides halted traffic in the municipal area. Multiple landslide warnings were also issued in other provinces. Northwestern provinces also braced for heavy rains following the system's second landfall.
Akash killed at least one fisherman, and left about 100 others missing. Crops were destroyed and power was cut as Akash neared the coast, and almost 80,000 people had to be evacuated to cyclone shelters. The seaport at Chittagong had to be closed, and all flights into and out of the city were cancelled.
The cyclone caused about $4 billion in damage (2007 USD) and 49 deaths in Oman, where the cyclone was considered the nation's worst natural disaster. Gonu dropped heavy rainfall near the eastern coastline, reaching up to 610 mm (24 inches) which caused flooding and heavy damage. In Iran, the cyclone caused 23 deaths and $215 million in damage (2007 USD).
Early on June 21, the India Meteorological Department (IMD) declared the area a depression, 430 km (270 mi) east-southeast of Kakinada, Andhra Pradesh, India. Several hours later, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA), with winds near 30 kt (55 km/h, 35 mph). The depression moved quickly west-northwest towards the northern Andhra Pradesh coast. A subtropical ridge to the north weakened the wind shear which had been paralysing the system, allowing for further intensification. Later that day, the IMD upgraded the system to a deep depression. As convection organised with increasing ocean heat content, the JTWC issued its first warning on Tropical Cyclone 03B.
The deep depression made landfall near Kakinda early on June 22 local time. The JTWC issued its final advisory later, as the system began to weaken due to land interaction and wind shear. The next day, the IMD downgraded it to a depression while it crossed the Deccan Plateau. The final warning was issued on June 24, despite the storm having moved into the Arabian Sea. The storm killed at least 140 people in India, and another 213 people died in Karachi, Pakistan from rains and winds that might have been associated with an outer band of the cyclone. The Pakistan Meteorological Department (PMD) had warned of heavy rains and wind from the system as early as Friday June 22.
The JTWC noted in its Significant Tropical Weather Outlook for the North Indian Ocean on June 24 that strong monsoonal low-level flow contributed to increased cyclonic vorticity, with low vertical wind shear and warm sea surface temperatures. It warned that these factors could lead to a rapid regeneration of the cyclone. Early on June 25, the JTWC issued the second TCFA for this system as its LLCC crossed the coast into the Arabian Sea. Shortly after, both the IMD and the JTWC resumed advisories on the depression.
As it moved northwest just off the Pakistani coast, winds of about 26 kt (48 km/h, 30 mph) and a surface pressure of 990 mbar (hPa) were observed in Karachi near midday on June 25. According to the PMD, the centre of the system reached within 90 km (55 mi) of Karachi. With favourable conditions and deep convection, the system intensified into a deep depression that day. After further organization, it made its second landfall at about 0300 UTC June 26 along the Makran coast, near Ormara and Pasni, Balochistan province, in southwestern Pakistan. Upon reaching land, the cyclone began to weaken slowly, and the JTWC issued its last advisory late on June 26.
The cyclone trapped 2 merchant ships: Al-Picaso and Lady Hamad, and 4 fishing boats: Al-Taif, Al-Noor, Sumbal Sultani and Al-Tariq, 100 nm (185 km, 115 mi) off Karachi. The Pakistan Navy rescued 56 sailors from the merchant ships and 36 fishermen from the fishing boats after they were detected by Breguet Atlantique aircraft. The heavy downpour also flooded the Kech Korandi riverine, inundating the city of Turbat and causing more than 10,000 people to evacuate their houses. At least 380 people died in Balochistan, with another 250 dead in Sindh and 100 in the North-West Frontier Province, and further rains associated with the remnants of the cyclone hampered rescue efforts. The cyclone affected at least 10 districts of Balochistan and 4 districts of Sindh, affecting the lives of atleas 1.5 million people. Over 80 people were killed in floods associated with the remnants in Afghanistan. At least 2 million people were affected by the cyclone or indirectly by power cuts and water shortages in Balochistan.
The PMD referred to the deep depression as Tropical Cyclone Yemyin, the next name on the list at the time. The IMD did not operationally name the system, but the depression was upgraded to a cyclonic storm in post-analysis, and the IMD retroactively named it Yemyin.
At 0600 UTC (11 a.m. PST) on June 28, the Pakistan Meteorological Department (PMD) issued its first advisory regarding the remnants of the system. The PMD stated that the remnants "had the potential" to cause widespread heavy rain with strong winds in Sindh, Balochistan, Azad Kashmir and North-West Frontier provinces. This could worsen conditions in areas already flooded by Tropical Cyclone Yemyin. In its fourth advisory on July 1, the PMD warned about the "high probability" of the system moving westward towards southern Sindh (instead of northwestward as previously projected), and regenerating over the Arabian Sea. The remnants of Tropical Cyclone 04B were mentioned in a Significant Tropical Weather Advisory from the JTWC early on July 2. After crossing the Deccan Plateau, convection was southwest of the centre, in the Arabian Sea, while multiple associated low-level circulation centres had yet to re-emerge, and were located in west-central India, north-northeast of Mumbai. The area had favourable upper-level divergence, but high vertical wind shear. Eventually, the circulation centre became fully exposed in unfavourable conditions, and the JTWC declared it "no longer suspect for development" later that day.
While it was over western India adjoining the Arabian Sea, the deep convection associated with the remnants of the cyclone brought heavy rains to Maharashtra, causing disruptions in transport due to floods and high winds in Mumbai. Amravati district, northeast of Mumbai, was also severely affected by floods. At least 43 people were killed in the state, and in Mumbai 243 mm (9.6 in) of rain was recorded. 14 died in Gujarat state, and evacuations were conducted. Up to 462 mm (18.1 inches) of rain was received in Bharuch district.
As the system weakened while over north Chhattisgarh, the IMD downgraded it to a depression on July 7. The IMD then discontinued bulletins on July 8 as it weakened into a low pressure area over central Madhya Pradesh. However, early the next morning it reintensified into a depression near Shivpuri, in northwestern Madhya Pradesh, and the IMD resumed advisories. Later that day, the IMD issued its final bulletin.
The depression caused heavy rains in Kolkata, with 16 casualties. Nearly 20% of the cumulative rainfall for the entire monsoon season fell in three days.
On August 7, Pakistan Meteorological Department issued its first weather advisory regarding the probability of regeneration of the system in Arabian Sea after crossing the Indian state of Gujarat, but this never came to fruition.
As it intensified to a Category 4-equivalent cyclone on November 14, thousands of emergency officials were put on standby in eastern India and Bangladesh in advance of the storm's arrival. Massive evacuations of low-lying coastal areas also took place, although sheltering was only available for about 500,000 of the over 10 million residents of coastal areas. The IMD also issued a cyclone alert for Orissa and West Bengal on November 14. On the morning of November 15, the cyclone intensified to reach peak winds of 215 km/h (135 mph) according to the IMD, and a peak of 260 km/h (160 mph) according to the JTWC. Sidr officially made landfall around 1700 UTC later that day, with sustained winds of 215 km/h (135 mph). It weakened quickly after landfall and the final advisories were issued early on November 16. The name Sidr was contributed by Oman; it is an Arabic name of a tree belonging to the Ziziphus family, specifically the Ziziphus spina-christi.
In the post season analysis, Sidr was upgraded to a Category 5-equivalent cyclone. This marks the first time that there have been two Category 5-equivalent storms in the Northern Indian Ocean in a single season.