The unexpected appearance of a tornado in Nanjung Mekar Village, West Java, Indonesia, has spurred urgent research efforts as meteorologists ponder this unprecedented weather phenomenon.
The tornado, which ravaged hundreds of houses on Wednesday, February 21, took both residents and experts by surprise, prompting the Indonesian National Research and Innovation Agency (BRIN) to launch a comprehensive investigation.
According to the Jakarta Globe, Erma Yulihastin, a climatology expert at BRIN, said that the agency views this event as the “first of its kind in West Java” and has mobilised a research team to conduct an in-depth analysis.
"Our research team at BRIN will promptly conduct a reconstruction and investigation of the Rancaekek tornado on Wednesday. The chronology of photos and videos from the public and media is invaluable in assisting researchers to document this extreme weather, noted as the first tornado in the region," Yulihastin tweeted.
While the Meteorology, Climatology, and Geophysics Agency (BMKG) Station in Bandung has classified the event as a gustnado, BRIN insists it was a tornado, citing satellite imagery and wind speed measurements.
A gustnado is a brief, shallow surface-based vortex that forms within the downburst emanating from a thunderstorm.
It is a short-lived, ground-based swirling wind that can form on the leading edge of a severe thunderstorm.
Teguh Rahayu, Chief of the BMKG Class 1 Geophysics Station in Bandung, explained that gustnadoes, characterised by rotational forces with speeds below 70 kilometres per hour, are distinct from tornadoes, which have wind speeds exceeding 70 kilometres per hour.
"The tornado phenomenon has wind speeds exceeding 70 kilometres per hour. Yesterday evening's incident recorded wind speeds at the Jatinangor Automatic Weather Station (AWS) at 36.8 kilometres per hour," said Teguh in Bandung on Thursday.
Dr Yulihastin emphasised that the event in Rancaekek was not a gustnado but a tornado, citing satellite imagery as evidence.
"For the first time, the phenomenon of a small tornado can be detected from satellites," Erma said.
She explained that gustnadoes or small tornadoes have a micro-scale of 0-2 kilometres, whereas tornadoes are on a meso-scale, exceeding 2 kilometres.
"That's why predicting gustnadoes is very difficult because of their micro-scale. It is also challenging to detect them from satellites," she clarified.