Draft:Cyclone Darian

Severe Tropical Cyclone Darian
Very Intense Tropical Cyclone Darian

Cyclone Darian on 21 December after entering the South-West Indian Ocean basin.
Meteorological history
Formed	13 December 2022
Remnant low	29 December 2022
Dissipated	30 December 2022
Duration	2 weeks and 2 days
Category 5 severe tropical cyclone
10-minute sustained (BOM)
Highest winds	220 km/h (140 mph)
Lowest pressure	915 hPa (mbar); 27.02 inHg
Category 4-equivalent tropical cyclone
1-minute sustained (SSHWS/JTWC)
Highest winds	240 km/h (150 mph)
Overall effects
Fatalities	None
Damage	None
Areas affected	None
Part of the 2022–23 Australian region and South-West Indian Ocean cyclone seasons

Cyclone Darian was a powerful tropical cyclone which traversed the Indian Ocean in December 2022. The third tropical low, third named storm, first tropical cyclone and first severe tropical cyclone of the 2022–23 Australian region, Darian formed in the Australian basin on 13 December, before rapidly strengthening, it peaked at 21 December becoming one of the strongest tropical cyclones in the Australian basin on record with a barometric pressure measured at 920 millibars, before weakening, however, it was trying to restrengthen to become a Category 5, but, the storm failed to become a Category 5 tropical cyclone, and as it passed into the very low latitudes, it started weakening, before dissipating on 30 December 2022.

Meteorological history

Map plotting the storm's track and intensity, according to the Saffir–Simpson scale

Map key

Saffir–Simpson scale

  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown

Storm type

Tropical cyclone

Subtropical cyclone

Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

On 13 December, the BoM reported that Tropical Low 05U had formed approximately 170 km (110 mi) north of Cocos Islands, initially forecast to not develop further due to not conducive conditions. However, over the next 5 days, conditions improved, with vertical wind shear decreasing. At 11:30 UTC on 17 December, satellite imagery showed a partially exposed low-level center embedded in deep convection, prompting the JTWC's to issue a TCFA. The next day, the system strengthened into a Category 1-cyclone on the Australian scale, with BoM naming it Darian. Later that day, the JTWC initiated advisories on the system and classified it as Tropical Cyclone 05S. The BoM's assessed the cyclone to have strengthened into a Category 2 cyclone on 19 December and later to Category 3 cyclone on the Australian scale. By 15:00 UTC, the JTWC upgraded Darian to a Category 1-equivalent cyclone on the Saffir–Simpson hurricane wind scale (SSHWS), with maximum 1-sustained winds of 140 km/h (85 mph). Darian then strengthened to a Category 3 equivalent cyclone on the SSHWS in an environment of low wind shear, warm sea surface temperatures and good upper-level poleward outflow, which led to the storm having a symmetric 23 nautical miles (43 km; 26 mi) eye. The cyclone quickly intensified, and was upgraded to a Category 4 cyclone by the BoM. Similarly, the JTWC's further upgraded Darian to a Category 4-equivalent cyclone around 21:00 UTC, while exhibiting some annular characteristics. Darian continued to rapidly intensify, and reached Category 5 intensity on the Australian scale at 00:00 UTC on 21 December. Later that day, it exited the basin and moved into the South-West Indian Ocean basin. On 21 December, Severe Tropical Cyclone Darian moved into the basin from the Australian region, and was immediately classified as a very intense tropical cyclone by MFR. Darian exhibited a highly symmetrical cloud structure around a well-defined eye. Shortly afterward, Darian's cloud pattern deteriorated and its eye started to become less defined, causing the cyclone to weaken to an intense tropical cyclone by 18:00 UTC. Darian weakened to a Category 3-equivalent cyclone the next day, as the convective cloud tops had warmed slightly. Darian's then weakened due to strong wind shear, and was downgraded into a tropical cyclone. As a well-defined eye reappeared on satellite imagery, Darian re-intensified, reaching 10-minute maximum sustained winds of 165 km/h (105 mph) around 06:00 UTC on 23 December. The cyclone was highly compact, with a distinct eye surrounded by cold cloud tops. Around the same time, the JTWC's also assessed Darian as having 1-minute maximum sustained winds of 240 km/h (150 mph), making the storm a Category 4-equivalent cyclone again on the Saffir–Simpson scale (SSHWS). Darian became quasi-stationary due to the presence of two main flows. The cyclone's eye can be seen from satellite imagery, and its cloud tops warmed to −99 to −108 °F (−73 to −78 °C). Steady weakening occurred thereafter as it underwent an eyewall replacement cycle.

Multispectral animated satellite imagery revealed a 8 nautical miles (15 km; 9.2 mi) surrounded eye around deep convection as a result, the cyclone weakened to Category 2-equivalent cyclone. Further weakening occurred as the MFR assessed that Darian's winds bottomed out at 155 km/h (100 mph). At 03:00 UTC on 26 December, the JTWC reported that Darian had re-strengthened to 205 km/h (125 mph) with a warm 14 °F (−10 °C), a wide eye 25 nautical miles (46 km; 29 mi), and was surrounded by cold, −98 to −116 °F (−72 to −82 °C) cloud tops. Using the Dvorak technique, MFR estimated winds of 185 km/h (115 mph). Due to moderate east-northeasterly vertical wind shear, Darian fell to 155 km/h (100 mph) winds, according to MFR. Just six hours later, the eye feature persisted, consisting of a warm area within the cooling eyewall. At 15:00 UTC on 27 December, the JTWC further downgraded it to a Category 1-equivalent cyclone. Satellite imagery showed that the cloud pattern began to rapidly deteriorate, and MFR followed suit and declared it a severe tropical storm. The JTWC also reported that Darian's weakened into a tropical storm. By 00:00 UTC on 29 December, Darian weakened into a moderate tropical storm, after the convection diminished around the center. MFR issued its last advisory on the storm on 30 December as it transitioned into a post-tropical depression. The JTWC also discontinued warnings on the system around 03:00 UTC on 31 December.