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Cyclone Ilsa

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This is an old revision of this page, as edited by VCRPlusSubscription (talk | contribs) at 18:13, 13 April 2023 (Isla became a category 4 on the Australian scale). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
For other tropical cyclones of the same name, see Tropical Storm Ilsa.
Not to be confused with Tropical Storm Isa.

Severe Tropical Cyclone Ilsa
Current storm status
Category 4 severe tropical cyclone (Australian scale)
Current storm status
Category 4 tropical cyclone (1-min mean)
Satellite image
Forecast map
As of:12:00 UTC, 13 April 2023
Location:19°24′S 119°06′E / 19.4°S 119.1°E / -19.4; 119.1 (Severe Tropical Cyclone Ilsa) ± 10 nm
100 km (60 mi) NE of Port Hedland
70 km (45 mi) NNE of Pardoo Roadhouse
Sustained winds:115 kn (215 km/h; 130 mph) (10-min mean)
gusting to 160 kn (295 km/h; 185 mph)
130 kn (240 km/h; 150 mph) (1-min mean)
Pressure:928 hPa (27.40 inHg)
Movement:SSE at 8 kn (15 km/h; 9.2 mph)
See more detailed information.

Severe Tropical Cyclone Ilsa is an active and rapidly intensifying tropical cyclone currently making landfall in Western Australia. The sixth named storm, and the fifth severe tropical cyclone of the 2022–23 Australian region cyclone season, Ilsa formed from a tropical low off the coast of Indonesia on 5 April. It fluctuated in intensity and became a Category 1 tropical cyclone on 11 April, after deep convection became symmetric around the low-level circulation center. Ilsa then rapidly intensified the following day and became a Category 5 severe tropical cyclone on the Australian tropical cyclone intensity scale. Ten-minute sustained winds were estimated as 215 km/h (130 mph), with a central barometric pressure of 928 hPa (27.40 inHg). One-minute sustained winds reached 240 km/h (150 mph) at this time, equivalent to a Category 4 major hurricane on the Saffir–Simpson hurricane wind scale.

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
triangle Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression
Cyclone Ilsa continuing to intensify off the coast of Western Australia on 12 April

A tropical low was expected to form in the Timor or Arafura sea near northern Australia in the next few days, increasing the potential of tropical cyclone formation in the region.[1] During 30 March, the Australian Bureau of Meteorology (BoM) monitored a developing a tropical low which they classified as 23U.[2] By 5 April, the BoM reported that the tropical low had developed in Arafura Sea.[3] Deep convection persisted in the system's southern semicircles.[4] By 7 April, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA) on the system.[5] During the following day, the JTWC initiated advisories on the system and classified it as Tropical Cyclone 18S.[6]

Easterly vertical wind shear decreased as a result of the intense convective mass causing upper-level winds around it.[7] A central dense overcast (CDO) was later revealed to have developed on 10 April after deep convection became symmetric around the low-level circulation center.[8] Late on the next day, the BoM reported that the tropical low had developed into a Category 1 tropical cyclone and named it Ilsa.[9] By that time, it had developed an obscured low-level circulation center.[10] Satellite imagery showed that a CDO was obscuring the LLCC, and Ilsa intensified further into a Category 1-equivalent cyclone.[11] A burst of convection occurred near Ilsa's center during six hours later, and the BoM reported that it briefly strengthened into a Category 2 cyclone.[12] Ilsa rapidly intensified, into a Category 3-cyclone, within a favorable environment with low shear and warm sea surface temperature (SST).[13]

Ilsa shows an eye feature seen in microwave imaging, with IIsa later becoming a Category 2-equivalent cyclone.[14] The eye in the symmetric system later became visible on satellite imagery as the rainbands wrapped around the center tightened after intensifying to a Category 3-equivalent tropical cyclone.[15] Later the next day, the BoM assessed the storm to have attained ten-minute sustained winds of 165 km/h (105 mph), ranking it as a Category 4-cyclone.[16] During 13 April, the JTWC also assessed Ilsa to have attained an intensity equivalent to a Category 4-equivalent tropical cyclone on the Saffir–Simpson hurricane scale with winds of 215 km/h (130 mph).[17] An automated weather station on Rowley Shoals recorded wind gusts up to 235 km/h (146 mph).[18] Later that same day, Ilsa had become a Category 5 severe tropical cyclone with sustained winds of 205 km/h (125 mph).[19] A record-breaking ten-minute sustained wind speed of 218 km/h (135 mph) was measured at Bedout Island, beating the previous record of Cyclone George in 2007.[20]

Current storm information

As of 12:00 UTC 13 April, Severe Tropical Cyclone Ilsa is located within 10 nautical miles of 19°24′S 119°06′E / 19.4°S 119.1°E / -19.4; 119.1 (Ilsa) or about 100 km (60 mi) northeasst of Port Hedland and about 70 km (45 mi) north-northeast of Pardoo Roadhouse. Maximum 10-minute sustained winds are at 115 knots (215 km/h; 130 mph), with gusts up to 160 knots (295 km/h; 185 mph) while maximum 1-minute sustained winds are at 130 knots (240 km/h; 150 mph). The minimum central barometric pressure is 928 hPa (27.40 inHg), and the system is moving south-southeast at 8 kn (15 km/h; 9.2 mph).

For the latest official information, see:

Watches and warnings

Template:Australian cyclone warnings table

Preparations and impact

Gale-force winds with gusts up to 165 km/h (105 mph), and heavy rain might occur on 9 April between Kalumburu and Kuri Bay in the state's north.[21] Squally thunderstorms are also anticipated in far northern Kimberley.[21] Residents across the coast of Pilbara evacuated as high tides, large waves and inundation were possible.[22] In anticipation of Ilsa, the BoM issued a warning for Western Australia’s Kimberley and Pilbara regions.[23]

Extra emergency workers, aircraft and essential supplies have also been sent to the region.[24] On 12 April, the Department of Fire and Emergency Services (DFES) issued a cyclone yellow alert, and urged residents to be prudent and to take action and prepare to shelter.[25] At least 700 residents were being evacuated to cyclone shelters prior to the storm.[26] Port Hedland mayor Peter Carter said damaging winds could turn flying debris into "missiles in the air".[27]

See also

References

  1. ^ "Weekly Tropical Climate Note". Australian Bureau of Meteorology. 4 April 2023. Archived from the original on 9 April 2023. Retrieved 9 April 2023.
  2. ^ Tropical Cyclone Outlook for the Northern Region, including the Gulf of Carpentaria Issued at 2:15 pm CST on Thursday 30 March 2023 for the period until midnight CST Sunday 2 April 2023 (Report). Australian Bureau of Meteorology. 30 March 2023. Archived from the original on 4 April 2023. Retrieved 4 April 2023.
  3. ^ Tropical Cyclone Outlook for the Northern Region, including the Gulf of Carpentaria issued at 2:15 pm CST on Wednesday 5 April 2023 (Report). Australian Bureau of Meteorology. 5 April 2023. Archived from the original on 7 April 2023. Retrieved 7 April 2023.
  4. ^ Significant Tropical Weather Advisory for the Indian Ocean, 02Z 6 April 2022 (Report). United States Joint Typhoon Warning Center. 6 April 2022. Retrieved 6 April 2022. {{cite report}}: |archive-url= requires |archive-date= (help)
  5. ^ Tropical Cyclone Formation Alert (Invest 98S) (Report). United States Joint Typhoon Warning Center. 7 April 2023. Archived from the original on 7 April 2023. Retrieved 7 April 2023.
  6. ^ Prognostic Reasoning for Tropical Cyclone 18S (Eighteen) Warning No. 1 (Report). United States Joint Typhoon Warning Center. 8 April 2023. Archived from the original on 8 April 2023. Retrieved 8 April 2023.
  7. ^ Prognostic Reasoning for Tropical Disturbance 18S (Eighteen) Warning No. 3 (Report). United States Joint Typhoon Warning Center. 9 April 2023. Archived from the original on 9 April 2023. Retrieved 9 April 2023.
  8. ^ Prognostic Reasoning for Tropical Cyclone 18S (Eighteen) Warning No. 9 (Report). United States Joint Typhoon Warning Center. 9 April 2023. Archived from the original on 9 April 2023. Retrieved 9 April 2023.
  9. ^ "Tropical Cyclone Technical Bulletin (Western Region)". Australian Bureau of Meteorology. 11 April 2023. Archived from the original on 11 April 2023. Retrieved 11 April 2023.
  10. ^ Prognostic Reasoning for Tropical Cyclone 18S (Eighteen) Warning No. 11 (Report). United States Joint Typhoon Warning Center. 11 April 2023. Archived from the original on 11 April 2023. Retrieved 11 April 2023.
  11. ^ Prognostic Reasoning for Tropical Cyclone 18S (Ilsa) Warning No. 11 (Report). United States Joint Typhoon Warning Center. 11 April 2023. Archived from the original on 11 April 2023. Retrieved 11 April 2023.
  12. ^ "Tropical Cyclone Technical Bulletin (Western Region)". Australian Bureau of Meteorology. 11 April 2023. Archived from the original on 12 April 2023. Retrieved 12 April 2023.
  13. ^ "Tropical Cyclone Technical Bulletin (Western Region)". Australian Bureau of Meteorology. 12 April 2023. Archived from the original on 12 April 2023. Retrieved 12 April 2023.
  14. ^ Prognostic Reasoning for Tropical Cyclone 18S (Ilsa) Warning No. 15 (Report). United States Joint Typhoon Warning Center. 12 April 2023. Archived from the original on 12 April 2023. Retrieved 12 April 2023.
  15. ^ Prognostic Reasoning for Tropical Cyclone 18S (Ilsa) Warning No. 17 (Report). United States Joint Typhoon Warning Center. 12 April 2023. Archived from the original on 12 April 2023. Retrieved 12 April 2023.
  16. ^ Tropical Cyclone Forecast Track Map for Severe Tropical Cyclone Ilsa (Report). Australian Bureau of Meteorology. 13 April 2023. Archived from the original on 6 February 2023. Retrieved 13 April 2023.
  17. ^ Prognostic Reasoning for Tropical Cyclone 18S (Ilsa) Warning No. 18 (Report). United States Joint Typhoon Warning Center. 13 April 2023. Archived from the original on 12 April 2023. Retrieved 13 April 2023. {{cite report}}: |archive-date= / |archive-url= timestamp mismatch; 13 April 2023 suggested (help)
  18. ^ "Severe Tropical Cyclone Ilsa to cross WA coast as powerful category five system". ABC News. 13 April 2023. Archived from the original on 13 April 2023. Retrieved 13 April 2023.
  19. ^ "Tropical Cyclone Technical Bulletin (Western Region)". Australian Bureau of Meteorology. 13 April 2023. Archived from the original on 13 April 2023. Retrieved 13 April 2023.
  20. ^ Bureau of Meteorology, Western Australia [@BOM_WA] (13 April 2023). "#CycloneIlsa has set a new preliminary Australian ten-minute sustained wind speed record of 218km/h at Bedout Island! Cyclone George was the previous record holder with 194km/h back in 2007 at the very same location!" (Tweet). Archived from the original on 13 April 2023 – via Twitter.
  21. ^ a b "Tropical cyclone 'Ilsa' could hit parts of WA coast". WAtoday. 9 April 2023. Archived from the original on 9 April 2023. Retrieved 9 April 2023.
  22. ^ "Cyclone Ilsa: Residents flee as intensifying cyclone approaches northwest Australia". Alarabiya News. 12 April 2023. Archived from the original on 12 April 2023. Retrieved 12 April 2023.
  23. ^ Jarred, Cross (12 April 2023). "Pilbara and Kimberely prepare to shelter as Cyclone Ilsa reaches category 3, continues towards coast". Retrieved 13 April 2023.{{cite web}}: CS1 maint: url-status (link)
  24. ^ "Western Australia battens down as Cyclone Ilsa gathers strength". 1 News. Archived from the original on 12 April 2023. Retrieved 13 April 2023.
  25. ^ Anderson, Anthony (13 April 2023). "Tropical Cyclone Ilsa intensifies further to category 4 system". Retrieved 13 April 2023.{{cite web}}: CS1 maint: url-status (link)
  26. ^ "Cyclone Ilsa: Western Australia braces for category 4 storm". BBC News. 13 April 2023. Archived from the original on 13 April 2023. Retrieved 13 April 2023.
  27. ^ "Australia's northwest braces for strongest cyclone in a decade". www.aljazeera.com. Retrieved 13 April 2023.
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