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TROPICAL CYCLONE IRIS FORECAST & WARNINGS

News Warnings

TROPICAL CYCLONE IRIS FORECAST & WARNINGS

admin April 3, 2018
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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.

Headline:

Tropical cyclone warning is current for parts of the Lower Burdekin, Central Coast & Whitsunday Islands and adjacent inland areas.

Areas affected:

Warning zone: Ayr to Sarina, including Mackay and the Whitsunday Islands, and adjacent inland areas.

Watch zone: Sarina to St Lawrence.

Cancelled zones: None.

Details of Tropical Cyclone Iris at 7:00 am AEST:

Intensity: category 2, sustained winds near the centre of 100 kilometres per hour with wind gusts to 140 kilometres per hour.
Location: within 55 kilometres of 17.5 degrees South, 148.8 degrees East , 290 kilometres northeast of Townsville and 405 kilometres north of Mackay .
Movement: slow moving .

Tropical cyclone Iris has continued to intensify while moving southward overnight and is currently a category 2 cyclone.

Tropical cyclone Iris is expected to continue moving slowly to the south through most of today while continuing to intensify, before curving more to the southeast, parallel to the Queensland coast, on Wednesday. At this stage, the cyclone is not expected to cross the Queensland coast but may approach the coast close enough to produce significant impacts.

Hazards:

DESTRUCTIVE WINDS extend outwards to 100 kilometres from the centre and may impact the coastal fringe and islands between Bowen and Mackay, including the Whitsunday Islands, from early Wednesday morning.

GALES extend outwards to around 200 kilometres from the centre and may develop about coastal and island communities between Ayr and St Lawrence, including Mackay and the Whitsunday Islands, from this evening or early Wednesday morning, then extend south to St Lawrence later on Wednesday.

Heavy rainfall which may lead to flash flooding may develop during Tuesday and Wednesday. A Flood Watch is current for coastal catchments between Rollingstone and St Lawrence.

Recommended Action:

People between Ayr and Sarina including Mackay and the Whitsunday Islands, and adjacent inland areas, should immediately commence or continue preparations, especially securing boats and property using available daylight hours.
– For cyclone preparedness and safety advice, visit Queensland’s Disaster Management Services website (www.disaster.qld.gov.au)
– For emergency assistance call the Queensland State Emergency Service (SES) on 132 500 (for assistance with storm damage, rising flood water, fallen trees on buildings or roof damage).

People between Sarina and St Lawrence should consider what action they will need to take if the cyclone threat increases.
– Information is available from your local government
– For cyclone preparedness and safety advice, visit Queensland’s Disaster Management Services website (www.disaster.qld.gov.au)
– For emergency assistance call the Queensland State Emergency Service (SES) on 132 500 (for assistance with storm damage, rising flood water, fallen trees on buildings or roof damage).

Details: 

Time (AEST) Intensity Category Latitude
(decimal deg.)
Longitude
(decimal deg.)
Estimated Position
Accuracy (km)
0hr 7 am April 3 2 17.5S 148.8E 55
+6hr 1 pm April 3 2 17.8S 149.0E 65
+12hr 7 pm April 3 2 18.1S 149.2E 75
+18hr 1 am April 4 3 18.4S 149.6E 95
+24hr 7 am April 4 3 18.7S 149.8E 110
+36hr 7 pm April 4 3 19.1S 150.4E 130
+48hr 7 am April 5 3 19.4S 150.7E 150
+60hr 7 pm April 5 2 19.5S 150.9E 170
+72hr 7 am April 6 2 19.4S 150.9E 195

TRACK MAP


TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1956 UTC 02/04/2018
Name: Tropical Cyclone Iris
Identifier: 24U
Data At: 1800 UTC
Latitude: 17.4S
Longitude: 148.6E
Location Accuracy: within 30 nm [55 km]
Movement Towards: south [189 deg]
Speed of Movement: 3 knots [6 km/h]
Maximum 10-Minute Wind: 55 knots [100 km/h]
Maximum 3-Second Wind Gust: 75 knots [140 km/h]
Central Pressure: 994 hPa
Radius of 34-knot winds NE quadrant: 70 nm [130 km]
Radius of 34-knot winds SE quadrant: 120 nm [220 km]
Radius of 34-knot winds SW quadrant: 120 nm [220 km]
Radius of 34-knot winds NW quadrant: 90 nm [165 km]
Radius of 48-knot winds NE quadrant: 30 nm [55 km]
Radius of 48-knot winds SE quadrant: 30 nm [55 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:    
Radius of Maximum Winds: 25 nm [45 km]
Dvorak Intensity Code: T3.5/3.5/D1.0/24HRS STT:D0.5/06HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 150 nm [280 km]
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]        : degrees     :      nm  [km]: knots[km/h]: hPa
+06:  03/0000: 17.7S 148.7E:     040 [075]:  055  [100]:  983
+12:  03/0600: 18.0S 148.9E:     050 [095]:  060  [110]:  977
+18:  03/1200: 18.3S 149.2E:     065 [120]:  065  [120]:  973
+24:  03/1800: 18.6S 149.5E:     075 [140]:  070  [130]:  968
+36:  04/0600: 19.1S 150.1E:     090 [170]:  070  [130]:  968
+48:  04/1800: 19.4S 150.5E:     110 [205]:  065  [120]:  971
+60:  05/0600: 19.6S 150.7E:     125 [230]:  060  [110]:  974
+72:  05/1800: 19.5S 150.8E:     135 [250]:  050  [095]:  983
+96:  06/1800: 18.9S 150.0E:     200 [370]:  035  [065]:  995
+120: 07/1800: 18.1S 148.8E:     290 [535]:  030  [055]:  998
REMARKS:
Convection has persisted near the low-level circulation centre through the
morning hours with improved curvature and banding in the last 6 hours.
Observations, radar imagery and a 1618Z microwave pass suggest the cyclone may
have adopted a more west-southwest track in the last six hours. A 1117Z ASCAT
pass showed a broad swathe of gales through the southwestern quadrant of the
system. On the western flank the automatic weather station at Holmes Reef has
recorded gales since 1430Z, and Flinders Reef recently recorded a peak of 58
knots. Current intensity set to 55 knots as a result. 

Dvorak analysis using a curved band pattern gave a 0.7 to 0.8 wrap. Three hourly
average yielded DT3.0 to 3.5. MET was 2.5 and PAT was 3.0, with the FT and CI of
3.5 based on the DT.

Due to the influence of an upper atmospheric anticyclone to the east, and an
upper atmospheric trough to the west wind shear had been 10-20 knots during
Monday and this inhibited the rate of development somewhat. Recent guidance
suggests that wind shear has dropped to around 10 knots during the past 6 to 12
hours and recent flare up convection near the low level circulation supports
this guidance. 

Other conditions are favourable for further development through approximately
the next 24 to 36 hours, and recent rapid development and latest guidance
suggests further intensification to category 3 is reasonably likely over this
period. Beyond this time the upper trough strengthens and moves over the system,
increasing the deep layer wind shear, so weakening is forecast from later
Wednesday.

Recent movement to the south has been due to the combination of a mid-level
anticyclone to the east of the system, combined with the influence of another
anticyclone to the southwest which has partially ridged under the system. These
two semi-competing steering influences will cause movement to be slow and
somewhat erratic for the next 12 hours or so. Beyond this time, the upper trough
described above should steer the system more to the southeast, parallel to the
Queensland coast. Though some uncertainty remains with the future path of the
cyclone, there remains reasonably high confidence that the system will not cross
the coast based on numerical deterministic and ensemble guidance.


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