#30 Postby Chacor » Thu Jan 26, 2012 9:02 pm
AXAU01 APRF 270050
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0050 UTC 27/01/2012
Name: Tropical Cyclone Iggy
Identifier: 11U
Data At: 0000 UTC
Latitude: 17.5S
Longitude: 110.7E
Location Accuracy: within 60 nm [110 km]
Movement Towards: east southeast [116 deg]
Speed of Movement: 7 knots [13 km/h]
Maximum 10-Minute Wind: 50 knots [95 km/h]
Maximum 3-Second Wind Gust: 70 knots [130 km/h]
Central Pressure: 979 hPa
Radius of 34-knot winds NE quadrant: 110 nm [205 km]
Radius of 34-knot winds SE quadrant: 90 nm [165 km]
Radius of 34-knot winds SW quadrant: 90 nm [165 km]
Radius of 34-knot winds NW quadrant: 110 nm [205 km]
Radius of 48-knot winds NE quadrant: 60 nm [110 km]
Radius of 48-knot winds SE quadrant: 45 nm [85 km]
Radius of 48-knot winds SW quadrant: 45 nm [85 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 50 nm [95 km]
Dvorak Intensity Code: T3.5/3.5/D0.5/24HRS STT:D0.5/6HRS
Pressure of outermost isobar: 996 hPa
Radius of outermost closed isobar: 180 nm [335 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 27/1200: 18.4S 111.7E: 090 [165]: 050 [095]: 978
+24: 28/0000: 19.0S 112.3E: 120 [220]: 060 [110]: 969
+36: 28/1200: 19.5S 113.0E: 150 [280]: 070 [130]: 960
+48: 29/0000: 19.6S 113.5E: 185 [345]: 080 [150]: 951
+60: 29/1200: 19.8S 113.7E: 230 [430]: 090 [165]: 941
+72: 30/0000: 20.0S 113.9E: 280 [520]: 090 [165]: 941
REMARKS:
TC Iggy has shown some development overnight with the early VIS imagery showing
increased curvature and the LLCC more closely involved with the deep convection.
A shear analysis gives DT3.5 with the LLCC under the overcast by more than 1/3
deg. ASCAT pass at 14Z indicated 50 knot winds to the north with a larger gale
radius in the northern semicircle than in the south.
The ridge to the south is very weak and steering is dominated by the monsoon
flow to the north, bringing the system SE towards the coast. Models indicate a
general southeast movement is maintained for around 48 hours before sufficient
ridging develops to the south to steer the system to the southwest. Not all
models develop sufficient ridging to alter the course, with a few models
maintaining a SE course bringing Iggy across the Pilbara coast. There has been a
trend in the model guidance towards more southeast movement prior to recurving
to the west and this is reflected in the ensemble outputs. Most models have the
closest approach to the coast occurring late Sunday or Monday but it may produce
gales on the coast as early as Saturday evening.
Although intensification may be slow today as shear remains around 18 knots on
the latest analysis, models indicate only light to moderate shear over the next
72 hours with the possibility that an upper trough will interact favourably and
provide upper cyclonic vorticity and an outflow channel to the SE. Hence steady
intensification is forecast with the system reaching severe in 36 to 48 hours.
Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 27/0700 UTC by Perth TCWC.
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