Weather Warnings - Tropical Cyclone Bulletin

Tropical Cyclone Technical Bulletin: AUSTRALIA - Western Australia
Issued by Australian Government Bureau of Meteorology TROPICAL CYCLONE WARNING CENTRE
at: 0651 UTC 29/03/2025
Name: Severe Tropical Cyclone Courtney
Identifier: 27U
Data At: 0600 UTC
Latitude: 18.1S
Longitude: 90.8E
Location Accuracy: within 15nm (30 km)
Movement Towards: west southwest (252 deg)
Speed of Movement: 12 knots (21 km/h)
Maximum 10-Minute Wind: 100 knots (185 km/h)
Maximum 3-Second Wind Gust: 140 knots (260 km/h)
Central Pressure: 947 hPa
Radius of 34-knot winds NE quadrant: 60 nm (110 km)
Radius of 34-knot winds SE quadrant: 70 nm (130 km)
Radius of 34-knot winds SW quadrant: 70 nm (95 km)
Radius of 34-knot winds NW quadrant: 50 nm (95 km)
Radius of 48-knot winds NE quadrant: 30 nm (55 km)
Radius of 48-knot winds SE quadrant: 35 nm (65 km)
Radius of 48-knot winds SW quadrant: 30 nm (55 km)
Radius of 48-knot winds NW quadrant: 30 nm (55 km)
Radius of 64-knot winds: 20 nm (20 km)
Radius of Maximum Winds: 10 nm (20 km)
Dvorak Intensity Code: T5.5/6.0/D1.5/24HRS STT:W0.5/06HRS
Pressure of outermost isobar: 1006 hPa
Radius of outermost closed isobar: 200 nm (370 km)

FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
(UTC) : degrees : nm (km): knots(km/h): hPa
+06: 29/1200: 18.7S 89.9E: 030 (050): 100 (185): 944
+12: 29/1800: 19.3S 89.1E: 035 (065): 095 (175): 948
+18: 30/0000: 19.9S 88.4E: 045 (080): 090 (165): 952
+24: 30/0600: 20.6S 87.8E: 045 (085): 085 (155): 956
+36: 30/1800: 21.8S 87.6E: 060 (105): 075 (140): 964
+48: 31/0600: 22.8S 87.8E: 075 (145): 065 (120): 971
+60: 31/1800: 23.3S 88.0E: 105 (190): 050 (095): 982
+72: 01/0600: 23.8S 87.3E: 125 (230): 035 (065): 992
+96: 02/0600: 25.0S 85.0E: 165 (305): 030 (055): 997
+120: 03/0600: 26.9S 80.6E: 195 (360): 030 (055): 998

REMARKS:
Severe Tropical Cyclone Courtney has maintained category 4 intensity. Severe TC Courtney was located using EIR satellite imagery. Dvorak analysis: 3 hour average eye patterns, Eno 5.0 for LG surround, eye adj +0.5 from a OW in W surround (eye is regular), yields a DT of 5.5. MET=5.5 with no PT adjustment. FT is 5.5 with CI held at 6.0. Objective aids (all 1-min mean): ADT 115kn, AiDT 112kn, DPRINT 113 kn, DMINT 116 kn, SATCON 113kn. Intensity is set at 100 knots consistent with subjective Dvorak and objective guidance. The environment is favourable for STC Courtney to hold its intensity for the next 12-18 hours given the warm SSTs of 28C and low vertical wind shear of around 5-10 knots from CIMSS analysis. There is also an upper trough to the south increasing outflow and upper divergence south of the centre. Given this favourable environment it is possible Courtney may intensify a little more in the short term, however most intensity guidance does not support this. The environmental steering is consistent in guidance, with generally southwest motion forecast for the remainder of Saturday due to a mid-level ridge to the south. Into Sunday the motion becomes more to the south as the ridge retreats ahead of another upper trough developing in the central Indian Ocean. From Sunday 30 March weakening should commence under increasing wind shear, dry air and movement over cooler waters. Models indicate a spread in track motion in the longer term, there is the possibility Courtney turns to the southeast or resumes on a more westward track as it weakens.

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There will be no further bulletins for this system.

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