Cyclone Warnings
at: 1251 UTC 23/03/2018
Name: Severe Tropical Cyclone Marcus
Identifier: 20U
Data At: 1200 UTC
Latitude: 22.7S
Longitude: 106.1E
Location Accuracy: within 20 nm [35 km]
Movement Towards: south [169 deg]
Speed of Movement: 14 knots [26 km/h]
Maximum 10-Minute Wind: 75 knots [140 km/h]
Maximum 3-Second Wind Gust: 105 knots [195 km/h]
Central Pressure: 965 hPa
Radius of 34-knot winds NE quadrant: 120 nm [220 km]
Radius of 34-knot winds SE quadrant: 120 nm [220 km]
Radius of 34-knot winds SW quadrant: 130 nm [240 km]
Radius of 34-knot winds NW quadrant: 110 nm [205 km]
Radius of 48-knot winds NE quadrant: 50 nm [95 km]
Radius of 48-knot winds SE quadrant: 50 nm [95 km]
Radius of 48-knot winds SW quadrant: 50 nm [95 km]
Radius of 48-knot winds NW quadrant: 50 nm [95 km]
Radius of 64-knot winds: 30 nm [55 km]
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T5.0/5.0/W0.5/24HRS STT:S0.0/06HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 180 nm [335 km]
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]        : degrees     :      nm  [km]: knots[km/h]: hPa
+06:  23/1800: 24.0S 106.4E:     030 [060]:  065  [120]:  973
+12:  24/0000: 25.3S 106.7E:     045 [080]:  055  [100]:  980
+18:  24/0600: 26.5S 106.9E:     055 [105]:  045  [085]:  986
+24:  24/1200: 27.4S 107.1E:     070 [130]:  040  [075]:  988
+36:  25/0000: 29.2S 107.7E:     090 [165]:  035  [065]:  991
+48:  25/1200: 31.4S 109.7E:     110 [200]:  030  [055]:  996
+60:  26/0000: 35.0S 114.6E:     130 [235]:  030  [055]:  996
+72:  26/1200: 38.3S 121.7E:     145 [270]:  025  [045]:  998
+96:  27/1200: 42.2S 133.4E:     190 [355]:  025  [045]:  995
+120: 28/1200:             :              :            :     
Marcus was located using animated VIS imagery and several microwave passes
through the afternoon. Marcus has continued weakening with an eye no longer
identifiable in EIR, microwave imagery shows deep convection is now confined to
the southern quadrants.

Dvorak: Embedded centre pattern: Surrounding grey shade is B which gives a CF of
5.0. The cold convection in EIR is fluctuating with the CF number between 4.5
and 5.0 over the last 6 hours. MET is 5.0 based on W- 24hr trend, adj MET and FT
are 5.0. CI is held at 5.0. CIMMS and NESDIS ADT are decreasing rapidly with 1
minute wind at around 60 knots. Recent microwave imagery produced a SATCON
estimate at 0700 UTC which was at 83 knots 1-minute wind. Intensity is set at 75

The mid-level trough to the west of Marcus is now the dominant steering
mechanism. Recent movement hsa been showing signs of a south southeast trend
developing. This is likely to continue as the system moves further south. 

The 0600 UTC vertical wind shear from CIMSS is still low at 6 knots from the W.
The shear will start to increase steadily as the system continues to track in a
southward direction. The equatorward outflow channel has weakened substantially,
though poleward outflow is still evident on sat imagery. As the system moves
further south overnight Friday, closer to the mid-level trough, these conditions
will become less favourable.

CIMSS TPW shows drier air wrapping around the northern side of the system and is
cutting the system off from the moist tropical environment.

Marcus is now moving over cooler water, SSTs will decrease below 26C and Ocean
Heat Content becoming unfavourable.

Marcus is expected to weaken below tropical cyclone intensity late Saturday or
early Sunday.

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The next bulletin for this system will be issued by: 23/1930 UTC by Perth TCWC.
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Severe Tropical Cyclone Marcus

Issued at 8:47 pm AWST Friday 23 March 2018. No Tropical Cyclone Advice is current for this system.

Community Threat

Warning Zone
Gales within 24 hours
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Watch Zone
Gales from 24-48 hours
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Past Cyclone Details

Past Location and Intensity Number
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Past Track and Movement
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Current Cyclone Details

Current Location and Intensity Number
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Very Destructive Winds
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Destructive Winds
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Gale Force Winds
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Forecast Cyclone Details
(Up to 72 hours from time of issue)

Forecast Location and Intensity Number
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Very Destructive Wind Boundary
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Destructive Wind Boundary
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Gale Force Wind Boundary
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Most Likely Future Track
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Range of Likely Tracks of Cyclone Centre
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The forecast path shown above is the Bureau's best estimate of the cyclone's future movement and intensity. There is always some uncertainty associated with tropical cyclone forecasting and the grey zone indicates the range of likely tracks of the cyclone centre.

Due to the uncertainty in the future movement, the indicated winds will almost certainly extend to regions outside the rings on this map. The extent of the warning and watch zones reflects this.

This product is designed for land-based communities; mariners should read the coastal waters and high seas warnings.


Severe Tropical Cyclone Marcus continues to weaken well away from the WA mainland

Areas affected:

Warning zone: None.

Watch zone: None.

Cancelled zones: None.

Details of Severe Tropical Cyclone Marcus at 8:00 pm AWST:

Intensity: category 3, sustained winds near the centre of 140 kilometres per hour with wind gusts to 195 kilometres per hour.
Location: within 35 kilometres of 22.7 degrees South, 106.1 degrees East , 830 kilometres west of Exmouth and 810 kilometres west northwest of Carnarvon .
Movement: south at 26 kilometres per hour .

Severe Tropical Cyclone Marcus is weakening as it moves southward, well away from the WA mainland. Marcus will continue moving generally southward and weaken further overnight Friday and into Saturday. Marcus will weaken below tropical cyclone intensity late Saturday or early Sunday, well off the west coast of WA.


Severe Tropical Cyclone Marcus is well away from the WA mainland and is not expected to directly affect WA communities.


  Time (AWST) Intensity Category Latitude
(decimal deg.)
(decimal deg.)
Estimated Position
Accuracy (km)
0hr 8 pm March 23 3 22.7S 106.1E 35
+6hr 2 am March 24 3 24.0S 106.4E 60
+12hr 8 am March 24 2 25.3S 106.7E 80
+18hr 2 pm March 24 1 26.5S 106.9E 105
+24hr 8 pm March 24 1 27.4S 107.1E 130
+36hr 8 am March 25 tropical low 29.2S 107.7E 165
+48hr 8 pm March 25 tropical low 31.4S 109.7E 200
+60hr 8 am March 26 tropical low 35.0S 114.6E 235
+72hr 8 pm March 26 tropical low 38.3S 121.7E 270

Tropical Cyclone information is also available in MetEye

Next Issue

The next Forecast Track Map will be issued by 3:00 am AWST Saturday