Waves of 4-6 meters fall into the "very high" category, it said.
"Meanwhile, the wave height in the southern waters of West Java, Central Java, and Yogyakarta is estimated to be around 2.5-4 meters," chief technician at the Cilacap Meteorological Station Teguh Wardoyo said on Saturday.
The increase in wave height has been caused by wind patterns in the southern part of Indonesia, which are dominantly moving from east to southeast with wind speeds ranging from 8-20 knots.
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In such cases, the pattern of wind movement with high speed triggers an increase in wave height, he added.
"Therefore, we have issued an early warning of high waves, effectively from Saturday at 7 a.m. local time, until September 25, at 7 a.m.," Wardoyo informed.
Furthermore, potential "high" waves of 2.5 to 4 meters have been forecast in the southern waters of Sukabumi, Cianjur, Garut, Tasikmalaya, Pangandaran, Cilacap, Kebumen, Purworejo, and Yogyakarta, he said.
Meanwhile, potential "very high" waves of 4 to 6 meters have been forecast in the Southern Indian Ocean off Sukabumi, Cianjur, Garut, Tasikmalaya, Pangandaran, Cilacap, Kebumen, Purworejo, and Yogyakarta, he added.
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Wardoyo then appealed to those venturing to sea to pay attention to the risk of high waves.
Traditional fishermen who use small boats are advised to remain alert for wind speeds of more than 15 knots and wave heights above 1.25 meters, he stated.
Barge operators are advised to be aware of winds with speeds of more than 16 knots and wave heights above 1.5 meters, he added.
Ferries are advised to be on alert for wind speeds of more than 21 knots and wave heights above 2.5 meters, while large ships such as cargo or cruise ships are advised to be wary of wind speeds of more than 27 knots and wave heights above 4 meters, he said.
Meanwhile, tourists visiting beaches, especially in the coastal areas that are directly connected to the high seas, are advised not to swim since high waves can occur at any time, he cautioned.
"People who live and work on the coast around areas that are prone to high waves are asked to stay alert," Wardoyo reiterated.
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Translator: Sumarwoto, Resinta Sulistiyand
Editor: Fardah Assegaf
Copyright © ANTARA 2021
