| Subtropical Depression (SSHWS) | |
|---|---|
 | |
| Formed | 28 March 2389 |
| Dissipated | 29 March 2389 |
| Highest winds | 1-minute sustained: 55 km/h (35 mph) |
| Lowest pressure | 1008 hPa (mbar); 29.77 inHg |
| Fatalities | None |
| Damage | Minimal |
| Areas affected | Davis Station, Australian Antarctica |
The 2389 Davis Station subtropical depression, also known as Cyclone Davis, was a historic, anomalous, and extraordinarily rare system that became the first recorded subtropical or tropical cyclone to make landfall in the Antarctic continent, as well as the third recorded subtropical or tropical cyclone to form in the Southern ocean.
During the later period of the 2388-2389 Southern hemisphere cyclone seasons, a subtropical depression, initially thought to be a polar low, was identified just off the coast of the Australian Antarctic Territory, which was located in eastern Antarctica. Moving east, the storm coalesced into a subtropical depression early on 28 March, impacting Davis station before making landfall in mainland Antarctica, all of which occurred over the course of 28 March. The system dissipated shortly after its landfall during the morning hours of 29 March.
The storm was noted to have caused minimal damage to human settlements located on the continent, specifically the aforementioned Davis station, which the cyclone was named after following its dissipation. The cyclone set multiple meteorological records during its short and unusual life, with subsequent reports concerning the system receiving significant news and media coverage.
Meteorological history[]
Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
Tropical storm (39–54 mph, 63–87 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)
Extratropical cyclone / remnant low, tropical disturbance, or monsoon depressionOn 19 March, weather models began showing an embedded low within a strong low pressure system just off the coast of Australian Antarctica, predicting development in a little under a week. By late 25 March, a non-tropical disturbance had formed near 68.5° S and 71° E. Like models had predicted, it formed while embedded within a larger extratropical low.
Following its development, the nascent low began to drift eastward. Along the way, it was met with unusually favorable conditions for potential (sub)tropical development; however, at the time, the formation of such cyclones so close to the Antarctic was considered impossible. Despite this, as it continued to head eastward near the Antarctic coast, the low began exhibiting some tropical characteristics, including the development of convection near the center and some separation from the larger non-tropical low that was influencing the storm.
The storm is estimated to have officially transitioned into a subtropical depression at 00:00 UTC on 28 March after it attained a warm core. At the time of its transition, it was situated at 68.6° S and 74.8° E. Additionally, it was also estimated to have contained 35 mph (55 km/h) 1-minute sustained winds upon subtropical cyclogenesis, with a barometric pressure of 1008 millibars (29.77 inHg); this would later prove to be the storm's peak intensity.
Now moving east north-east, the cyclone slowed down a bit in the late morning hours of 28 March after having sped up slightly the previous night. Around 13:30 UTC that same day, the center of the storm passed just south of Davis station, an Australian research base. After passing the base, the storm kept moving east north-east, now targeting the main continental landmass of Antarctica. At approximately 19:25 UTC, late on 28 March, the depression made landfall in mainland Antarctica; by this point, the cyclone had decayed slightly, containing 1-minute sustained winds of 30 mph (50 km/h) and a central barometric pressure of 1010 millibars (29.83 inHg). The cyclone rapidly deteriorated inland, and the storm had lost its identity by the morning hours of 29 March.
Classification of the system[]
Operationally, the cyclone was considered a polar low; as such, the Australian Bureau of Meteorology (BoM) issued bulletins and advisories on the system as a non-tropical entity in communications with the scientists at Davis station. It was initially believed to be a polar low due to its location; despite the fact that two cyclones had developed in the southern Ocean prior (specifically, in 2248 and 2341), no storm of tropical or subtropical nature had ever developed that close to the Antarctic continent.
However, in the years following the storm's existence, leading scientists in the field of meteorology, especially those specializing in cyclones of all types, began to question the classification of the system as a polar low. On 8 August 2392, Bill Kanik, a senior tropical cyclone forecaster at the BoM, released a report on Twitter Nu concerning the system. In the report, Kanik argued that the system was not a polar low, but rather a moderately weak subtropical depression; he pointed to the system's warm core and sufficiently organized convection as reasons.
In the years following Kanik's report, several other significant meteorologists, including then-head forecaster of the American National Hurricane Center (NHC), Jeffrey Nohl, remarked that the system was indeed of a subtropical nature. Regarding the unusual system, Nohl stated on Twitter Nu: "I unequivocally believe that the 2389 polar low which passed near the Australian Davis station in Antarctica was, indeed, actually a subtropical cyclone. It's quite cut and dry looking at the system, too.", which further increased support for a subtropical classification among the meteorological community.
The calls from within the community to address the system continued to grow throughout the following years. Said calls, along with more statements from top meteorologists and tropical cyclone experts such as Kanik and Nohl, resulted in the BoM issuing a report concerning the storm on 5 May 2399. The report, which was co-written by Kanik, confirmed the system's subtropical nature; upon its release, the report, as well as the system itself, received major news and media coverage as a result of the system's uniqueness. Interest in meteorology as a whole went up following the popularization of the story; by 2416, meteorology had emerged as one of fastest growing interests for youth across the globe, with Generation Pi being commonly referred to as the "Windy Generation" due to the generation's fondness of tracking the weather.
Preparations and impact[]
Preparations[]
With Davis station in the way of the forthcoming storm, the mainland BoM began communicating with the station, issuing advisories and bulletins on the system. In addition to that, the researchers had recently gotten in a new shipment of vital resources needed to weather the storm, including significant amounts of food and water. As a result of the aforementioned factors, the station was well-equipped to handle the storm's potential impact.
Impact[]
At the height of the storm, Davis station recorded rainfall of up to 4.82 inches (122.4 mm) within a 24 hour period, with 28 March 2389 becoming the station's wettest day since its 1957 establishment. In addition, gale-force gusts impacted the station, with a 49 mph (79 km/h) gust being recorded. No fatalities occurred due to the storm, and only minimal monetary damage was reported. On the station itself, damage was done to some of the island's scientific equipment as a result of strong rainfall, and three trucks used to drive around the island for research sustained minor damage following the storm's passing.
Records[]
The depression became the first recorded (sub)tropical cyclone to ever make landfall in Antarctica, a feat that was previously thought to be impossible. With it reaching as far south as 68.7° S, it became both the southernmost cyclone ever recorded and the furthest cyclone away from the equator ever recorded. It was the first system to exist as a (sub)tropical system south of 60° S in over 45 years, as well as the second in recorded history; the first and, at the time, only other system to do so was the 2341 Southern ocean subtropical storm. Additionally, even though both were (sub)tropical south of 60° S, the Davis cyclone was the first in recorded history to both form south of 60° S as well as spend its entire life below the aforementioned latitude; the 2341 system completed subtropical cyclogenesis at 59.3° S, thereby forming above the 60° S line. It was also the first recorded (sub)tropical cyclone in the Southern ocean to not attain sustained gale-force winds.