AXAU01 APRF 020106
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0105 UTC 02/04/2023
Name: Tropical Cyclone Herman
Identifier: 21U
Data At: 0000 UTC
Latitude: 19.7S
Longitude: 106.2E
Location Accuracy: within 15nm (30 km)
Movement Towards: west southwest (239 deg)
Speed of Movement: 4 knots (7 km/h)
Maximum 10-Minute Wind: 45 knots (85 km/h)
Maximum 3-Second Wind Gust: 65 knots (120 km/h)
Central Pressure: 994 hPa
Radius of 34-knot winds NE quadrant: 
Radius of 34-knot winds SE quadrant: 40 nm (75 km)
Radius of 34-knot winds SW quadrant: 50 nm (95 km)
Radius of 34-knot winds NW quadrant: 30 nm (55 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:  nm ( km)
Radius of Maximum Winds: 10 nm (20 km)
Dvorak Intensity Code: T3.0/3.5/W2.5/24HRS STT:W0.5
Pressure of outermost isobar: 1010 hPa
Radius of outermost closed isobar: 120 nm (220 km)
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
(UTC)        : degrees     :      nm  (km): knots(km/h): hPa
+06:  02/0600: 19.8S 105.9E:     030 (055):  035  (065):  996
+12:  02/1200: 19.9S 105.6E:     050 (095):  030  (055):  998
+18:  02/1800: 19.8S 105.3E:     065 (120):  030  (055): 1000
+24:  03/0000: 19.8S 105.0E:     080 (155):  030  (055): 1002
+36:  03/1200: 19.7S 104.4E:     115 (215):  030  (055): 1004
+48:  04/0000: 18.9S 103.1E:     140 (260):  030  (055): 1006
+60:  04/1200: 18.3S 101.6E:     165 (305):  030  (055): 1006
+72:  05/0000: 17.5S  99.7E:     185 (345):  030  (055): 1005
+96:  06/0000:             :              :            :     
+120: 07/0000:             :              :            :     
REMARKS:
Tropical Cyclone Herman continues to weaken rapidly and has turned to the west
southwest. 

Deep convection has weakened rapidly overnight and is now confined to a small
region south of the centre. This is a result of dry air being ingested into the
circulation assisted by 15-20kn of northerly vertical wind shear.   

Intensity 45kn. This is lower than standard metrics as these are less likely to
capture the rapid weakening expected from a small system but reflects model
guidance. There has been no recent scatterometry in past 12h. Dvorak analysis:
DT is becoming harder to assign but estimated at 2.0 on curved band pattern;
MET based on rapid weakening indicates 3.5 (4.0 adjusted down). FT constrained
to 3.0 and CI held at 3.5. Objective guidance (1minute mean): ADT raw numbers
2.0-2.5 but CI held at 4.1; AiDT 62kn; SATCON 18UTC 66kn. 

After being difficult to locate overnight, Herman is now readily identified on
microwave (GMI 2229UTC) and recent visible imagery. The motion is now more
definitively to the west southwest as was forecast. Steering influences are
weak so the circulation will continue to be slow moving with consistent
guidance suggestion a west northwest track.  

The hostile environment is likely to continue signalling the demise of
gale-force intensity within 12h. Gales may extend longest in the southwest
quadrant.  

Herman poses no threat to the coast.  

Copyright Commonwealth of Australia
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The next bulletin for this system will be issued by: 02/0730 UTC.