SIO: CALEB - Post-Tropical

[jaguarjace]

90S INVEST 170321 0600 11.1S 98.2E SHEM 20 1007


Tropical Cyclone Outlook for the Western Region
Issued at 2:06 pm WST on Tuesday 21 March 2017
for the period until midnight WST Friday 24 March 2017.

Potential Cyclones:
The monsoon trough lies along 12S between Cocos Islands and Christmas Island. A tropical low is expected to form in the trough near 12S 95-100E (Cocos Islands vicinity) on Wednesday but should move away to the southeast. The system is expected to develop on Thursday with an increased risk of becoming a tropical cyclone on Friday over open waters.

Likelihood of this system or another system becoming a tropical cyclone in the Western Region on:
Wednesday: Low,
Thursday: Low,
Friday: Moderate

[Digital-TC-Chaser]

Details of Tropical Cyclone Caleb at 2:00 pm AWST:

Intensity: category 1, sustained winds near the centre of 65 kilometres per hour with wind gusts to 95 kilometres per hour.
Location: within 55 kilometres of 12.6 degrees South, 100.5 degrees East , 400 kilometres east of Cocos Island and 610 kilometres west southwest of Christmas Island .
Movement: south southeast at 13 kilometres per hour .

Tropical Cyclone Caleb has formed in open waters between Cocos and Christmas Islands. Caleb is forecast to move in a south to southeasterly direction Thursday night and during Friday, away from the islands.

Tropical Cyclone Caleb is expected to remain over open waters, and is not expected to produce gales over Cocos or Christmas Islands or the WA mainland.

[Digital-TC-Chaser]

IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0142 UTC 24/03/2017
Name: Tropical Cyclone Caleb
Identifier: 23U
Data At: 0000 UTC
Latitude: 13.8S
Longitude: 101.1E
Location Accuracy: within 30 nm [55 km]
Movement Towards: south southeast [154 deg]
Speed of Movement: 4 knots [8 km/h]
Maximum 10-Minute Wind: 40 knots [75 km/h]
Maximum 3-Second Wind Gust: 55 knots [100 km/h]
Central Pressure: 995 hPa
Radius of 34-knot winds NE quadrant: 90 nm [165 km]
Radius of 34-knot winds SE quadrant: 60 nm [110 km]
Radius of 34-knot winds SW quadrant: 120 nm [220 km]
Radius of 34-knot winds NW quadrant: 120 nm [220 km]
Radius of 48-knot winds NE quadrant:
Radius of 48-knot winds SE quadrant:
Radius of 48-knot winds SW quadrant:
Radius of 48-knot winds NW quadrant:
Radius of 64-knot winds:
Radius of Maximum Winds: 30 nm [55 km]
Dvorak Intensity Code: T2.5/2.5/S0.0/24HRS STT:S0.0/06HRS
Pressure of outermost isobar: 1006 hPa
Radius of outermost closed isobar: 180 nm [335 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 24/0600: 14.2S 101.3E: 040 [080]: 045 [085]: 992
+12: 24/1200: 14.5S 101.4E: 055 [100]: 045 [085]: 991
+18: 24/1800: 14.7S 101.5E: 065 [125]: 040 [075]: 994
+24: 25/0000: 14.9S 101.5E: 080 [145]: 040 [075]: 994
+36: 25/1200: 15.3S 101.7E: 100 [180]: 040 [075]: 994
+48: 26/0000: 15.1S 101.4E: 120 [220]: 040 [075]: 994
+60: 26/1200: 15.0S 101.0E: 140 [255]: 035 [065]: 997
+72: 27/0000: 14.8S 100.3E: 155 [290]: 035 [065]: 998
+96: 28/0000: 14.7S 99.1E: 200 [370]: 035 [065]: 997
+120: 29/0000: 15.0S 98.1E: 290 [535]: 035 [065]: 997
REMARKS:
Tropical Cyclone Caleb is tracking southeast over open waters south of the Cocos
and Christmas Islands.

The system was located by microwave imagery overnight to the southeast of the
deep convection. Curvature of the deep convection on the 2059UTC microwave image
continues to remain weak and cloud tops have warmed over the last several hours.

The intensity of 40 knots is influenced by earlier ASCAT passes [02-03UTC],
which showed gales to the north, west and south of the somewhat elongated
centre. This is a little higher than the Dvorak analysis which yields a FT/CI of
2.5. This is based on a shear pattern with the low level centre under 0.75
degrees from the edge of the deep convection. Adjusted MET is 2.5.

Development has been supported by strong low-level forcing from monsoonal NW
flow to the north and SE'ly surge from the sub-tropical high to the south, and a
slight decrease in the shear over the system. Counterbalancing this has been a
weakening upper-level outflow pattern. Although the system is moving into a more
neutral shear environment, it appears drier air is starting to entrain through
the northeast flank and the system will become isolated from the monsoon flow in
the next 12 to 24 hrs. The ocean heat content becomes more marginal south of
15S. Gales in southern quadrants are likely to be maintained for several days
from the strong SE synoptic flow as a new sub-tropical ridge builds to the south
early next week.

The system is forecast to move in a south to southeasterly direction over the
coming 48 hours due to a strong monsoonal surge to the north and a mid level
trough and low to the southeast. Motion should become slow on Sunday as a
mid-level ridge starts to develop to the south of the system, and then from
Monday onward this should begin to steer the system in a westerly direction
although models do differ on the extent of the eastward movement before
recurving towards the west.