卡奔塔利亚湾热带低压30U(31P)

pocketbox

ABPW10 PGTW 171200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/171200Z-180600ZAPR2025//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 97P) PREVIOUSLY LOCATED NEAR
8.9S 136.7E IS NOW LOCATED NEAR 9.6S 137.5E, APPROXIMATELY 165 NM NORTH-
NORTHEAST OF GOVE AIRPORT, AUSTRAILIA. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY AND A 170918Z GMI 89GHZ IMAGE DEPICT A PARTIALLY
OBSCURED, CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
FLARING CONVECTION AND FORMATIVE BANDING WITHIN THE SOUTHWESTERN
QUADRANT. ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY FAVORABLE
ENVIRONMENT FOR DEVELOPMENT WITH MODERATE TO HIGH (20-25 KNOTS)
NORTHEASTERLY VERTICAL WIND SHEAR, GOOD POLEWARD UPPER-LEVEL OUTFLOW,
AND WARM (29-30 C) SEA SURFACE TEMPERATURES. DETERMINISTIC AND ENSEMBLE
MODELS ARE IN GOOD AGREEMENT, SHOWING GRADUAL INTENSIFICATION IN THE
GULF OF CARPENTARIA OVER THE NEXT 48 HOURS. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO
MEDIUM.
      (2) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: UPGRADED AREA IN PARA 2.B.(1) TO MEDIUM.//
NNNN

ygsj24

AXAU01 ADRM 171311
IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
ISSUED BY AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
AT: 1311 UTC 17/04/2025
NAME: TROPICAL LOW
IDENTIFIER: 30U
DATA AT: 1200 UTC
LATITUDE: 9.8S
LONGITUDE: 137.8E
LOCATION ACCURACY: WITHIN 40NM (75 KM)
MOVEMENT TOWARDS: SOUTHEAST (135 DEG)
SPEED OF MOVEMENT: 7 KNOTS (13 KM/H)
MAXIMUM 10-MINUTE WIND: 30 KNOTS (55 KM/H)
MAXIMUM 3-SECOND WIND GUST: 45 KNOTS (85 KM/H)
CENTRAL PRESSURE: 1002 HPA
RADIUS OF 34-KNOT WINDS NE QUADRANT:
RADIUS OF 34-KNOT WINDS SE QUADRANT:
RADIUS OF 34-KNOT WINDS SW QUADRANT:
RADIUS OF 34-KNOT WINDS NW QUADRANT:
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:   NM (  KM)
DVORAK INTENSITY CODE: T2.5/2.5/D1.0/24HRS STT:D0.5/06HRS
PRESSURE OF OUTERMOST ISOBAR: 1008 HPA
RADIUS OF OUTERMOST CLOSED ISOBAR: 160 NM (295 KM)
FORECAST DATA
DATE/TIME    : LOCATION    : LOC. ACCURACY: MAX WIND   : CENTRAL PRESSURE
(UTC)        : DEGREES     :      NM  (KM): KNOTS(KM/H): HPA
+06:  17/1800: 10.1S 138.5E:     050 (095):  030  (055): 1003
+12:  18/0000: 10.6S 139.0E:     060 (110):  030  (055): 1003
+18:  18/0600: 11.1S 139.6E:     060 (110):  030  (055): 1003
+24:  18/1200: 11.4S 139.9E:     055 (100):  030  (055): 1003
+36:  19/0000: 12.0S 140.4E:     070 (135):  035  (065):  999
+48:  19/1200: 12.4S 140.4E:     100 (190):  040  (075):  996
+60:  20/0000: 12.6S 139.9E:     125 (225):  040  (075):  997
+72:  20/1200: 12.5S 139.0E:     140 (260):  035  (065): 1000
+96:  21/1200: 11.7S 136.6E:     190 (355):  030  (055): 1003
+120: 22/1200: 10.5S 133.3E:     205 (375):  025  (045): 1006
REMARKS:
TROPICAL LOW 30U LIES OVER THE NORTHEAST ARAFURA SEA AND HAS BEEN MOVING
SOUTHEAST. THERE IS CURRENTLY ONLY MODERATE CONFIDENCE IN THE CENTRE POSITION,
WHICH IS BASED ON EXTRAPOLATION FROM AN 0918Z GMI PASS.

DVORAK ANALYSIS: CURVATURE HAS REDUCED IN THE PAST 6 HOURS, LEAVING A SHEAR
PATTERN AS THE MOST SUITABLE. THIS YIELDS DT OF 3.0, HOWEVER UNCERTAINTY IN
POSITION COULD AFFECT THE ANALYSIS. MET IS 2.5 WITH A D TREND AND NO ADJUSTMENT
TO PAT. FT/CI OF 2.5 BASED ON MET/PAT. INTENSITY IS SET AT 30 KN WHICH IS
CONSISTENT WITH MODEL GUIDANCE AND EARLIER SCATTEROMETRY PASSES. OBJECTIVE
GUIDANCE IS NOT YET AVAILABLE.

30U CURRENTLY LIES UNDER MODERATE TO STRONG NORTHEASTERLY VERTICAL WIND SHEAR,
UNDER THE WESTERN EDGE OF AN UPPER ANTICYCLONE. AS 30U TRACKS TO THE SOUTHEAST,
IT MAY MOVE UNDER THE AXIS OF THE ANTICYCLONE AND SHEAR MAY EASE. THIS COULD
ALLOW THE CURRENTLY TILTED VORTEX TO BECOME MORE VERTICAL THROUGH THE DEPTH OF
THE ATMOSPHERE. DEEP TROPICAL MOISTURE AND HIGH SEA SURFACE TEMPERATURES
(30-31C) ARE OTHERWISE IN PLACE IN THE SHORT TO MEDIUM TERM, ALTHOUGH DRY AIR
MAY AFFECT THE SYSTEM FROM LATER ON SUNDAY.
GOOD UPPER OUTFLOW, PARTICULARLY TO THE NORTH, IS ALSO PRESENT. SOME GUIDANCE
SUGGESTS OUTFLOW MAY IMPROVE OVER THE WEEKEND AS AN UPPER TROUGH MOVES TO THE
SOUTH, BUT OTHER GUIDANCE REDUCES UPPER SUPPORT WITH THE TROUGH REMAINING TOO
FAR SOUTH AND EQUATORWARD OUTFLOW DECREASING. THE LEVEL OF UPPER SUPPORT MAY BE
THE KEY TO WHETHER 30U CAN DEVELOP. AS A SMALL SYSTEM, IT COULD RESPOND RAPIDLY
TO ANY IMPROVEMENT IN ITS ENVIRONMENT, AND IT HAS SOME POTENTIAL TO REACH
TROPICAL CYCLONE INTENSITY QUICKLY GIVEN THE RIGHT CONDITIONS.

LOW-LEVEL WESTERLY FLOW IS CURRENTLY STEERING 30U TO THE SOUTHEAST. THIS FLOW
IS EXPECTED TO SOMEWHAT INCREASE ON FRIDAY, WITH SLIGHTLY FASTER MOTION TO THE
SOUTHEAST. INTO THE WEEKEND A DEEPER CIRCULATION MAY CONTINUE TO BE STEERED TO
THE SOUTH SOUTHEAST WITH THE INFLUENCE OF A MID-LEVEL ANTICYCLONE TO THE
SOUTHEAST. FROM LATE WEEKEND OR EARLY NEXT WEEK, A HIGH PRESSURE RIDGE IS
EXPECTED TO STRENGTHEN OVER CENTRAL AUSTRALIA, STEERING 30U TO THE WEST OR
NORTHWEST, TOWARDS THE EASTERN TOP END. HOWEVER, THERE IS HIGH UNCERTAINTY IN
THE TRACK AT THIS LEAD TIME.

COPYRIGHT COMMONWEALTH OF AUSTRALIA
==
THE NEXT BULLETIN FOR THIS SYSTEM WILL BE ISSUED BY: 17/1930 UTC.=




Headline:
Tropical low 30U a Moderate chance of developing into a tropical cyclone.


Areas affected:
Warning zone: None.

Watch zone: None.

Cancelled zones: None.


Details of Tropical Low 30U at 9:30 pm ACST:
Intensity: tropical low, sustained winds near the centre of 55 kilometres per hour with wind gusts to 85 kilometres per hour.
Location: within 75 kilometres of 9.8 degrees South, 137.8 degrees East , 290 kilometres north northeast of Nhulunbuy and 480 kilometres north northeast of Alyangula .
Movement: southeast at 13 kilometres per hour .

Tropical Low 30U is located in the eastern Arafura Sea, and is forecast to move southeast towards the Gulf of Carpentaria on Friday and into the weekend.

If 30U remains over waters it has a Moderate chance of developing into a tropical cyclone from Friday evening through to Sunday in the Gulf of Carpentaria.


Details:

	Time (ACST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	10 pm April 17	tropical low	9.8S	137.8E	75
+6hr	4 am April 18	tropical low	10.1S	138.5E	95
+12hr	10 am April 18	tropical low	10.6S	139.0E	110
+18hr	4 pm April 18	tropical low	11.1S	139.6E	110
+24hr	10 pm April 18	tropical low	11.4S	139.9E	100
+36hr	10 am April 19	tropical low	12.0S	140.4E	135
+48hr	10 pm April 19	tropical low	12.4S	140.4E	190
+60hr	10 am April 20	tropical low	12.6S	139.9E	225
+72hr	10 pm April 20	tropical low	12.5S	139.0E	260

Tropical Cyclone information is also available in MetEye


Next Issue
The next Forecast Track Map will be issued by 4:30 am ACST Friday

ygsj24

AXAU01 ADRM 171925
IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
ISSUED BY AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
AT: 1925 UTC 17/04/2025
NAME: TROPICAL LOW
IDENTIFIER: 30U
DATA AT: 1800 UTC
LATITUDE: 9.9S
LONGITUDE: 138.4E
LOCATION ACCURACY: WITHIN 40NM (75 KM)
MOVEMENT TOWARDS: EAST SOUTHEAST (110 DEG)
SPEED OF MOVEMENT: 7 KNOTS (14 KM/H)
MAXIMUM 10-MINUTE WIND: 30 KNOTS (55 KM/H)
MAXIMUM 3-SECOND WIND GUST: 45 KNOTS (85 KM/H)
CENTRAL PRESSURE: 1001 HPA
RADIUS OF 34-KNOT WINDS NE QUADRANT:
RADIUS OF 34-KNOT WINDS SE QUADRANT:
RADIUS OF 34-KNOT WINDS SW QUADRANT:
RADIUS OF 34-KNOT WINDS NW QUADRANT:
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:   NM (  KM)
DVORAK INTENSITY CODE: T2.5/2.5/D1.0/24HRS STT:S0.0/06HRS
PRESSURE OF OUTERMOST ISOBAR: 1006 HPA
RADIUS OF OUTERMOST CLOSED ISOBAR: 160 NM (295 KM)
FORECAST DATA
DATE/TIME    : LOCATION    : LOC. ACCURACY: MAX WIND   : CENTRAL PRESSURE
(UTC)        : DEGREES     :      NM  (KM): KNOTS(KM/H): HPA
+06:  18/0000: 10.4S 139.2E:     050 (095):  035  (065):  999
+12:  18/0600: 10.9S 139.8E:     060 (110):  035  (065):  998
+18:  18/1200: 11.3S 140.2E:     060 (110):  035  (065):  998
+24:  18/1800: 11.7S 140.5E:     055 (105):  035  (065):  998
+36:  19/0600: 12.3S 140.8E:     080 (150):  040  (075):  995
+48:  19/1800: 12.6S 140.4E:     100 (180):  035  (065):  997
+60:  20/0600: 12.7S 139.5E:     125 (230):  035  (065):  998
+72:  20/1800: 12.6S 138.3E:     140 (255):  030  (055): 1001
+96:  21/1800: 11.9S 135.6E:     190 (350):  030  (055): 1001
+120: 22/1800: 10.5S 132.5E:     205 (385):  025  (045): 1004
REMARKS:
TROPICAL LOW 30U LIES OVER THE NORTHEAST ARAFURA SEA AND HAS BEEN MOVING
SOUTHEAST. THERE IS CURRENTLY ONLY MODERATE CONFIDENCE IN THE CENTRE POSITION,
WHICH IS BASED ON EXTRAPOLATION FROM AN 1157Z ASCAT-C PASS.

DVORAK ANALYSIS: CURVED BAND WITH A WRAP OF AROUND 0.4 YIELDS DT OF 2.5. MET IS
2.5 WITH A D TREND AND NO ADJUSTMENT TO PAT. FT/CI OF 2.5 BASED ON MET/PAT.
INTENSITY IS SET AT 30 KN WHICH IS CONSISTENT WITH MODEL GUIDANCE. AN ASCAT-C
PASS AT 1157Z HAD A SMALL AREA OF GALES IN THE SW QUADRANT, BUT THIS APPEARED
TO BE RAIN AFFECTED. INTENSITY SET TO 30 KNOTS. OBJECTIVE GUIDANCE IS NOT YET
AVAILABLE.

GALES ARE FORECAST TO DEVELOP IN THE SW QUADRANT UNDER THE PERSISTENT
CONVECTION WITHIN THE NEXT 6 HOURS. GALES MAY EXTEND INTO THE SE QUADRANT ON
SATURDAY.

30U CURRENTLY LIES UNDER MODERATE TO STRONG NORTHEASTERLY VERTICAL WIND SHEAR,
UNDER THE WESTERN EDGE OF AN UPPER ANTICYCLONE. AS 30U TRACKS TO THE SOUTHEAST,
IT MAY MOVE UNDER THE AXIS OF THE ANTICYCLONE AND SHEAR MAY EASE. THIS COULD
ALLOW THE CURRENTLY TILTED VORTEX TO BECOME MORE VERTICAL THROUGH THE DEPTH OF
THE ATMOSPHERE. DEEP TROPICAL MOISTURE AND HIGH SEA SURFACE TEMPERATURES
(30-31C) ARE OTHERWISE IN PLACE IN THE SHORT TO MEDIUM TERM, ALTHOUGH DRY AIR
MAY AFFECT THE SYSTEM FROM LATER ON SUNDAY.
GOOD UPPER OUTFLOW, PARTICULARLY TO THE NORTH, IS ALSO PRESENT. SOME GUIDANCE
SUGGESTS OUTFLOW MAY IMPROVE OVER THE WEEKEND AS AN UPPER TROUGH MOVES TO THE
SOUTH, BUT OTHER GUIDANCE REDUCES UPPER SUPPORT WITH THE TROUGH REMAINING TOO
FAR SOUTH AND EQUATORWARD OUTFLOW DECREASING. THE LEVEL OF UPPER SUPPORT MAY BE
THE KEY TO WHETHER 30U CAN DEVELOP. AS A SMALL SYSTEM, IT COULD RESPOND RAPIDLY
TO ANY IMPROVEMENT IN ITS ENVIRONMENT, AND IT HAS SOME POTENTIAL TO REACH
TROPICAL CYCLONE INTENSITY QUICKLY GIVEN THE RIGHT CONDITIONS.

LOW-LEVEL WESTERLY FLOW IS CURRENTLY STEERING 30U TO THE SOUTHEAST. THIS FLOW
IS EXPECTED TO SOMEWHAT INCREASE ON FRIDAY, WITH SLIGHTLY FASTER MOTION TO THE
SOUTHEAST. INTO THE WEEKEND A DEEPER CIRCULATION MAY CONTINUE TO BE STEERED TO
THE SOUTH SOUTHEAST WITH THE INFLUENCE OF A MID-LEVEL ANTICYCLONE TO THE
SOUTHEAST. FROM LATE WEEKEND OR EARLY NEXT WEEK, A HIGH PRESSURE RIDGE IS
EXPECTED TO STRENGTHEN OVER CENTRAL AUSTRALIA, STEERING 30U TO THE WEST OR
NORTHWEST, TOWARDS THE EASTERN TOP END. HOWEVER, THERE IS HIGH UNCERTAINTY IN
THE TRACK AT THIS LEAD TIME.

COPYRIGHT COMMONWEALTH OF AUSTRALIA
==
THE NEXT BULLETIN FOR THIS SYSTEM WILL BE ISSUED BY: 18/0130 UTC.=




Headline:
Tropical low 30U a Moderate chance of developing into a tropical cyclone.


Areas affected:
Warning zone: None.

Watch zone: None.

Cancelled zones: None.


Details of Tropical Low 30U at 3:30 am ACST:
Intensity: tropical low, sustained winds near the centre of 55 kilometres per hour with wind gusts to 85 kilometres per hour.
Location: within 75 kilometres of 9.9 degrees South, 138.4 degrees East , 310 kilometres northeast of Nhulunbuy and 495 kilometres north northeast of Alyangula .
Movement: east southeast at 14 kilometres per hour .

Tropical Low 30U is located in the eastern Arafura Sea, and is forecast to move southeast into the Gulf of Carpentaria on the weekend.

If 30U remains over waters it has a Moderate chance of developing into a tropical cyclone from Friday evening through to Sunday in the Gulf of Carpentaria.


Details:

	Time (ACST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	4 am April 18	tropical low	9.9S	138.4E	75
+6hr	10 am April 18	tropical low	10.4S	139.2E	95
+12hr	4 pm April 18	tropical low	10.9S	139.8E	110
+18hr	10 pm April 18	tropical low	11.3S	140.2E	110
+24hr	4 am April 19	tropical low	11.7S	140.5E	105
+36hr	4 pm April 19	tropical low	12.3S	140.8E	150
+48hr	4 am April 20	tropical low	12.6S	140.4E	180
+60hr	4 pm April 20	tropical low	12.7S	139.5E	230
+72hr	4 am April 21	tropical low	12.6S	138.3E	255

Tropical Cyclone information is also available in MetEye


Next Issue
The next Forecast Track Map will be issued by 10:30 am ACST Friday

ygsj24

WTPS21 PGTW 172130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 97P)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 9.8S 138.6E TO 13.1S 140.2E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 28 TO 33 KNOTS. METSAT
IMAGERY AT 171800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 10.0S 138.6E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 97P) PREVIOUSLY LOCATED
NEAR 9.7N 137.9E IS NOW LOCATED NEAR 10.0N 138.6E, APPROXIMATELY
172 NM NORTHEAST OF GOVE AIRPORT, AUSTRALIA. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS A DEEP AND PERSISTENT AREA OF CONVECTION.
UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH WARM SEA
SURFACE TEMPERATURES (30C), LOW VERTICAL WIND SHEAR (10-15KT), DEEP
TROPICAL MOISTURE, AND GOOD POLEWARD OUTFLOW. GLOBAL MODELS ARE IN
GOOD AGREEMENT WITH 97P TRACKING SOUTHEASTWARD WITH DEVELOPMENT AND
STEADY INTENSIFICATION IN THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 998 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
182130Z.
//
NNNN

---

ABPW10 PGTW 172130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/172130Z-180600ZAPR2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/172121ZAPR2025//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 97P) PREVIOUSLY LOCATED NEAR
8.9S 136.7E IS NOW LOCATED NEAR 10.0S 138.6E, APPROXIMATELY 178 NM
NORTHEAST OF GOVE AIRPORT, AUSTRALIA. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A DEEP AND PERSISTENT AREA OF CONVECTION. UPPER-LEVEL
ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH WARM SEA SURFACE
TEMPERATURES (30C), LOW VERTICAL WIND SHEAR (10-15KT), DEEP TROPICAL
MOISTURE, AND GOOD POLEWARD OUTFLOW. GLOBAL MODELS ARE IN GOOD AGREEMENT
WITH 97P TRACKING SOUTHEASTWARD WITH DEVELOPMENT AND STEADY
INTENSIFICATION IN THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 998 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH. SEE REF A
(WTPS21 PGTW 172130) FOR FURTHER DETAILS.
      (2) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: UPGRADED AREA IN PARA. 2.B.(1) TO HIGH.//
NNNN

pocketbox

IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0154 UTC 18/04/2025
Name: Tropical Low  
Identifier: 30U
Data At: 0000 UTC
Latitude: 11.1S
Longitude: 138.9E
Location Accuracy: within 25nm (45 km)
Movement Towards: southeast (140 deg)
Speed of Movement: 8 knots (16 km/h)
Maximum 10-Minute Wind: 35 knots (65 km/h)
Maximum 3-Second Wind Gust: 50 knots (95 km/h)
Central Pressure: 1000 hPa
Radius of 34-knot winds NE quadrant:
Radius of 34-knot winds SE quadrant:
Radius of 34-knot winds SW quadrant: 50 nm (95 km)
Radius of 34-knot winds NW quadrant:
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:   nm (  km)
Dvorak Intensity Code: T2.5/2.5/D1.0/24HRS STT:S0.0/06HRS
Pressure of outermost isobar: 1008 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:  18/0600: 11.6S 139.2E:     035 (070):  035  (065): 1000
+12:  18/1200: 11.9S 139.7E:     045 (085):  035  (065): 1000
+18:  18/1800: 12.2S 140.0E:     055 (100):  035  (065): 1000
+24:  19/0000: 12.4S 140.3E:     060 (105):  035  (065): 1000
+36:  19/1200: 12.7S 140.3E:     085 (160):  040  (075):  996
+48:  20/0000: 12.9S 139.8E:     115 (210):  035  (065):  999
+60:  20/1200: 12.8S 138.8E:     130 (245):  035  (065): 1003
+72:  21/0000: 12.4S 137.3E:     145 (265):  035  (065): 1003
+96:  22/0000: 11.6S 134.6E:     190 (350):  030  (055): 1003
+120: 23/0000: 10.3S 131.8E:     210 (390):  030  (055): 1003
REMARKS:
Tropical Low 30U moving southeast in the Gulf of Carpentaria.  

Vis and microwave imagery SSMIS 2132UTC have indicated an improved band of deep
convection south of the centre.  

Position based on microwave and animated vis imagery with good confidence.

Intensity 35 kn estimated from early ASCAT imagery combined with ongoing deep
convection in the southwest quadrant.

Dvorak analysis: FT/CI=2.5. DT=3.0 based on most recent curved band wrap of 0.6
but can consider longer time averaged value a little less. MET is 2.5 from 24h
D trend with no PAT adjustment. An ASCAT-C pass at 1157Z had a small area of
gales in the SW quadrant, but in heavy rain region. Objective guidance is not
yet available.

Gales are analysed southwest of the centre and forecast to extend to southeast
quadrant shortly and to persist owing to ongoing deep convection with upper
level outflow support poleward of the circulation.  

30U currently lies under moderate to strong northeasterly vertical wind shear,
under the western edge of an upper anticyclone.  30U should move southeast into
a lower shear region which should support development along with high sea
surface temperatures (30-31C). However guidance shows an incursion of dry air
from the north and northeast to offset development potential.

Overall model guidance does not suggest significant intensification, however it
would only take a brief increase in deep convection over the centre to support
enhancement of the winds especially given the small size of the system. This is
somewhat dependent on the degree of upper level support and association with an
upper trough to the south. Some TC models (HFSA/COAMPS) does suggest
development as a result.   

As a small system, it could respond rapidly to any improvement in its
environment, and it has some potential to reach tropical cyclone intensity
quickly given the right conditions.

Low-level westerly flow is currently steering 30U to the southeast. A mid-level
anticyclone to the southeast is likely to become more dominant influence on
Saturday resulting in a slow southerly motion. From late weekend or early next
week, a high pressure ridge is expected to strengthen over central Australia,
steering 30U to the west northwest, towards the eastern Top End and eventually
into the Timor Sea by mid-next week when another opportunity for redevelopment
presents.  

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 18/0730 UTC.

	Time (ACST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	10 am April 18	tropical low	11.1S	138.9E	45
+6hr	4 pm April 18	tropical low	11.6S	139.2E	70
+12hr	10 pm April 18	tropical low	11.9S	139.7E	85
+18hr	4 am April 19	tropical low	12.2S	140.0E	100
+24hr	10 am April 19	tropical low	12.4S	140.3E	105
+36hr	10 pm April 19	tropical low	12.7S	140.3E	160
+48hr	10 am April 20	tropical low	12.9S	139.8E	210
+60hr	10 pm April 20	tropical low	12.8S	138.8E	245
+72hr	10 am April 21	tropical low	12.4S	137.3E	265

	Time (AEST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	10 am April 18	tropical low	11.1S	138.9E	45
+6hr	4 pm April 18	tropical low	11.6S	139.2E	70
+12hr	10 pm April 18	tropical low	11.9S	139.7E	85
+18hr	4 am April 19	tropical low	12.2S	140.0E	100
+24hr	10 am April 19	tropical low	12.4S	140.3E	105
+36hr	10 pm April 19	tropical low	12.7S	140.3E	160
+48hr	10 am April 20	tropical low	12.9S	139.8E	210
+60hr	10 pm April 20	tropical low	12.8S	138.8E	245
+72hr	10 am April 21	tropical low	12.4S	137.3E	265

pocketbox

ABPW10 PGTW 180600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/180600Z-190600ZAPR2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/172121ZAPR2025//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 97P) PREVIOUSLY LOCATED NEAR
10.0N 138.6E IS NOW LOCATED NEAR 11.2S 139.2E, APPROXIMATELY 153 NM
EAST-NORTHEAST OF GOVE AIRPORT, AUSTRAILIA. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS AN AREA OF PERSISTENT DEEP CONVECTION
PARTIALLY OBSCURING A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). A
PARTIAL 180045Z ASCAT METOP-C IMAGE REVEALED AN AREA OF 30 KTS WITHIN
THE WESTERN SEMICIRCLE OF RELATIVELY SYMMETRICAL CIRCULATION.
ENVIRONMENTAL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH WARM SEA
SURFACE TEMPERATURES (30 C), LOW VERTICAL WIND SHEAR (10-15 KTS), DEEP
TROPICAL MOISTURE, AND GOOD POLEWARD OUTFLOW. GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT 97P WILL TRACK SOUTHEASTWARD WITH DEVELOPMENT AND GRADUAL
INTENSIFICATION OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH. SEE REF A
(WTPS21 PGTW 172130) FOR FURTHER DETAILS.
      (2) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
NNNN

pocketbox

IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0703 UTC 18/04/2025
Name: Tropical Low  
Identifier: 30U
Data At: 0600 UTC
Latitude: 11.3S
Longitude: 139.7E
Location Accuracy: within 25nm (45 km)
Movement Towards: southeast (133 deg)
Speed of Movement: 7 knots (13 km/h)
Maximum 10-Minute Wind: 35 knots (65 km/h)
Maximum 3-Second Wind Gust: 50 knots (95 km/h)
Central Pressure: 998 hPa
Radius of 34-knot winds NE quadrant:
Radius of 34-knot winds SE quadrant:
Radius of 34-knot winds SW quadrant: 60 nm (110 km)
Radius of 34-knot winds NW quadrant:
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:   nm (  km)
Dvorak Intensity Code: T2.5/2.5/D1.0/24HRS STT:S0.0/06HRS
Pressure of outermost isobar: 1006 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:  18/1200: 11.5S 140.2E:     035 (070):  035  (065):  998
+12:  18/1800: 11.8S 140.4E:     045 (085):  035  (065):  998
+18:  19/0000: 12.2S 140.6E:     055 (100):  035  (065):  998
+24:  19/0600: 12.5S 140.7E:     060 (110):  035  (065):  997
+36:  19/1800: 12.6S 140.2E:     085 (155):  040  (075):  995
+48:  20/0600: 12.7S 139.4E:     105 (195):  035  (065):  998
+60:  20/1800: 12.4S 138.2E:     115 (210):  035  (065):  998
+72:  21/0600: 12.1S 136.8E:     130 (240):  030  (055): 1001
+96:  22/0600: 11.1S 133.7E:     170 (315):  030  (055): 1001
+120: 23/0600:  9.8S 131.0E:     205 (380):  030  (055): 1001
REMARKS:
Tropical Low 30U is a marginal tropical cyclone risk over the Easter weekend.  

Vis imagery shows an exposed centre east of ongoing deep convection, hence the
position is estimated with good confidence.  

Intensity 35 kn, based on ongoing deep convection with strong winds on the edge
of an earlier ASCAT-C swathe.

Dvorak analysis: FT/CI=2.5. DT=2.5 based on curved band wrap of 0.4-0.5 while
MET is 2.5 from 24h D- trend with no PAT adjustment. Objective guidance is not
yet available.

30U is a small circulation with gales only 60nm from centre southwest of the
centre.  

30U currently lies under moderate to strong northeasterly vertical wind shear,
under the western edge of an upper anticyclone. 30U should continue to move
southeast into a lower shear region which should support development along with
high sea surface temperatures (30C). However guidance shows an incursion of dry
air from the north and northeast to offset development potential as already
evidenced.

Overall model guidance does not suggest significant intensification. However it
would only take a brief increase in deep convection over the centre to support
enhancement of winds especially given the small size of the system. This is
somewhat dependent on the degree of upper level support and association with an
upper trough to the south. Some TC models (HFSA/COAMPS) do suggest development
as a result.   

Low-level westerly flow is currently steering 30U to the southeast. A mid-level
anticyclone to the southeast is likely to become the more dominant influence on
Saturday resulting in a slow southerly motion and then a turn to the west as
the steering ridge is expected to strengthen over central Australia. This takes
30U towards the eastern Top End by Monday and eventually into the Timor Sea by
mid-next week when another opportunity for potential development presents.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 18/1330 UTC.

	Time (ACST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	4 pm April 18	tropical low	11.3S	139.7E	45
+6hr	10 pm April 18	tropical low	11.5S	140.2E	70
+12hr	4 am April 19	tropical low	11.8S	140.4E	85
+18hr	10 am April 19	tropical low	12.2S	140.6E	100
+24hr	4 pm April 19	tropical low	12.5S	140.7E	110
+36hr	4 am April 20	1	12.6S	140.2E	155
+48hr	4 pm April 20	tropical low	12.7S	139.4E	195
+60hr	4 am April 21	tropical low	12.4S	138.2E	210
+72hr	4 pm April 21	tropical low	12.1S	136.8E	240

	Time (AEST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	4 pm April 18	tropical low	11.3S	139.7E	45
+6hr	10 pm April 18	tropical low	11.5S	140.2E	70
+12hr	4 am April 19	tropical low	11.8S	140.4E	85
+18hr	10 am April 19	tropical low	12.2S	140.6E	100
+24hr	4 pm April 19	tropical low	12.5S	140.7E	110
+36hr	4 am April 20	1	12.6S	140.2E	155
+48hr	4 pm April 20	tropical low	12.7S	139.4E	195
+60hr	4 am April 21	tropical low	12.4S	138.2E	210
+72hr	4 pm April 21	tropical low	12.1S	136.8E	240

yhh

WTPS31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 001//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/172121ZAPR2025//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 001   
   01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   180600Z --- NEAR 11.2S 139.7E
     MOVEMENT PAST SIX HOURS - 110 DEGREES AT 08 KTS
     POSITION ACCURATE TO WITHIN 030 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   REPEAT POSIT: 11.2S 139.7E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   181800Z --- 11.9S 140.4E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 140 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   190600Z --- 12.4S 140.8E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 250 DEG/ 02 KTS
    ---
   36 HRS, VALID AT:
   191800Z --- 12.5S 140.5E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 270 DEG/ 04 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   200600Z --- 12.5S 139.7E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 280 DEG/ 06 KTS
    ---
   72 HRS, VALID AT:
   210600Z --- 12.0S 137.1E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 295 DEG/ 07 KTS
    ---
   LONG RANGE OUTLOOK:
    ---
   96 HRS, VALID AT:
   220600Z --- 10.8S 134.3E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   VECTOR TO 120 HR POSIT: 300 DEG/ 08 KTS
    ---
   120 HRS, VALID AT:
   230600Z --- 9.3S 131.5E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
    ---
REMARKS:
180900Z POSITION NEAR 11.4S 139.9E.
18APR25. TROPICAL CYCLONE 31P (THIRTYONE), LOCATED APPROXIMATELY
523 NM EAST OF DARWIN, AUSTRALIA, HAS TRACKED EAST-SOUTHEASTWARD
AT 08 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 180600Z IS 998 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 180600Z IS 14 FEET.
NEXT WARNINGS AT 181500Z, 182100Z, 190300Z AND 190900Z.//
2. THIS CANCELS AND SUPERSEDES REF A (WTPS21 PGTW 172130)
NNNN

1. WDPS31 PGTW 180900
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 31P (THIRTYONE) WARNING
   
4. NR 001//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 11.2S 139.7E
    
11.    INITIAL INTENSITY: 35 KTS
    
12.    GEOGRAPHIC REFERENCE: 523 NM EAST OF DARWIN, AUSTRALIA
    
13.    MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 08 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 14 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
    
18. CYCLONE 31P WITH A WELL-DEFINED, PARTIALLY EXPOSED LOW-LEVEL
    
19. CIRCULATION CENTER (LLCC) AND FLARING CONVECTION ALONG THE
    
20. SOUTHWESTERN QUADRANT OF THE SYSTEM. ENVIRONMENTAL ANALYSIS
    
21. INDICATES THAT 31P IS IN A MARGINALLY FAVORABLE ENVIRONMENT
    
22. CHARACTERIZED BY MODERATE (15-20 KTS) EASTERLY VERTICAL WIND SHEAR,
    
23. WEAK OUTFLOW ALOFT, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.
    
24. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
    
25. PARTIALLY EXPOSED LLCC IN ANIMATED MSI. THE INITIAL INTENSITY OF 35
    
26. KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A PARTIAL 180045Z
    
27. METOP-C ASCAT IMAGE SHOWING 30-35 KTS WITHIN THE WESTERN
    
28. SEMICIRCLE. ADDITIONALLY, AGENCY DVORAK ESTIMATES RANGE FROM
    
29. 2.0-2.5, FURTHER SUPPORTING THE INITIAL INTENSITY ASSESSMENT.
    
30. 
    
31. INITIAL WIND RADII BASIS: SCATTEROMETER DATA AND OBJECTIVE BEST
    
32. TRACK
    
33. 
    
34. CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A NEAR-EQUATORIAL
    
35. RIDGE (NER) EXTENDING TO THE NORTH OF THE SYSTEM.
    
36. 
    
37. AGENCY DVORAK AND AUTOMATED FIXES:
    
38.    PGTW: T2.5 - 35 KTS
    
39.    KNES: T2.0 - 30 KTS
    
40.    ADRM: T2.5 - 35 KTS
    
41. 
    
42. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
    
43.    VWS: 15-20 KTS
    
44.    SST: 29-30 CELSIUS
    
45.    OUTFLOW: WEAK POLEWARD
    
46. 
    
47. ANALYSIS CONFIDENCE:
    
48.    INITIAL POSITION: HIGH
    
49.    INITIAL INTENSITY: HIGH
    
50.    INITIAL WIND RADII: LOW
    
51. 
    
52. 3. FORECAST REASONING.
    
53. 
    
54. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
    
55. MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.
    
56. 
    
57. FORECAST DISCUSSION: TC 31P IS FORECAST TO TRACK SOUTHEASTWARD
    
58. THROUGH TAU 24, ALONG THE SOUTHERN PERIPHERY OF THE NER. NEAR TAU
    
59. 24, RIDGING WILL BEGIN TO BUILD TO THE SOUTH OF THE SYSTEM, CAUSING
    
60. 31P TO TURN SHARPLY WESTWARD. AS THE RIDGE BUILDS TO THE SOUTH AND
    
61. BEGINS TO PROPAGATE WESTWARD, THE STEERING PATTERN WILL BECOME MORE
    
62. DEFINED, ALLOWING FOR AN INCREASE IN TRACK SPEEDS AS THE VORTEX
    
63. RIDES ALONG THE NORTHEASTERN PERIPHERY OF THE RIDGE THROUGH THE END
    
64. OF THE FORECAST PERIOD. REGARDING INTENSITY, 31P IS EXPECTED TO
    
65. REMAIN IN A MARGINAL ENVIRONMENT DUE TO THE ABSENCE OF A GOOD
    
66. OUTFLOW CHANNEL AND SOME SLIGHT DRY AIR ENTRAINMENT ALONG THE
    
67. WESTERN PERIPHERY. HOWEVER, SHEAR IS EXPECTED TO BEGIN SLIGHTLY
    
68. DECREASING AFTER TAU 12 TO AROUND 10-15 KTS. OVERALL, NO
    
69. SIGNIFICANT INTENSIFICATION IS CURRENTLY EXPECTED THROUGHOUT THE
    
70. FORECAST PERIOD AT THIS TIME.
    
71. 
    
72. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
    
73. AGREEMENT WITH ALL MODELS DEPICTING THE SHARP TURN AFTER TAU 24.
    
74. THE ECMWF AND GFS ENSEMBLES ALSO HAVE NO MAJOR SPREAD BETWEEN
    
75. MEMBERS, SUPPORTING THE JTWC TRACK FORECAST. INTENSITY GUIDANCE IS
    
76. IN AGREEMENT THROUGH TAU 84, WITH ALL MODELS SUGGESTING A NEARLY
    
77. STEADY INTENSITY OF AROUND 35 KTS. AFTER TAU 84, COAMPS-TC AND HWRF
    
78. SUGGEST INTENSIFICATION. THOSE MODEL TRACKERS DO KEEP THE VORTEX
    
79. FURTHER AWAY FROM LAND INTERACTION THAN THE REMAINDER OF GUIDANCE.
    
80. THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM
    
81. CONFIDENCE THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER.
    
82. 
    
83. FORECAST CONFIDENCE:
    
84.    TRACK 0 - 72 HR: MEDIUM
    
85.    TRACK 72-120 HR: MEDIUM
    
86.    INTENSITY 0 - 72 HR: MEDIUM
    
87.    INTENSITY 72-120 HR: LOW//
    
88. NNNN

复制代码

pocketbox

IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 1331 UTC 18/04/2025
Name: Tropical Low  
Identifier: 30U
Data At: 1200 UTC
Latitude: 11.6S
Longitude: 140.3E
Location Accuracy: within 25nm (45 km)
Movement Towards: east southeast (114 deg)
Speed of Movement: 8 knots (14 km/h)
Maximum 10-Minute Wind: 30 knots (55 km/h)
Maximum 3-Second Wind Gust: 45 knots (85 km/h)
Central Pressure: 1000 hPa
Radius of 34-knot winds NE quadrant:
Radius of 34-knot winds SE quadrant:
Radius of 34-knot winds SW quadrant:
Radius of 34-knot winds NW quadrant:
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:   nm (  km)
Dvorak Intensity Code: T2.0/2.5/S0.0/24HRS STT:W0.5/06HRS
Pressure of outermost isobar: 1008 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:  18/1800: 11.8S 140.5E:     035 (070):  030  (055): 1002
+12:  19/0000: 11.9S 140.7E:     045 (085):  030  (055): 1002
+18:  19/0600: 12.0S 140.9E:     055 (100):  030  (055): 1002
+24:  19/1200: 12.2S 140.9E:     060 (105):  030  (055): 1002
+36:  20/0000: 12.5S 140.6E:     075 (145):  035  (065):  999
+48:  20/1200: 12.4S 139.6E:     095 (180):  035  (065): 1000
+60:  21/0000: 12.1S 138.3E:     115 (210):  035  (065): 1000
+72:  21/1200: 11.6S 136.8E:     130 (245):  030  (055): 1003
+96:  22/1200: 10.4S 134.1E:     170 (315):  030  (055): 1003
+120: 23/1200:  9.2S 131.8E:     190 (350):  025  (045): 1005
REMARKS:
Tropical Low 30U has lost it deep convection and the low level centre is
exposed. Location is based on persistence, animated satellite imagery and Weipa
radar with good confidence.  

Intensity is set at 30 kn.

Dvorak analysis: FT/CI=2.0/2.5. DT is inconclusive due to an exposed
circulation. 24-hr trend of W gives MET 1.5 and PT is 2.0. Objective guidance
at 1240 UTC: ADT 35 kn, AiDT 34 kn and DPRINT 27 kn.

30U lies under moderate northeasterly vertical wind shear (CIMSS 17 kn), under
the western edge of an upper anticyclone. There is evidence of incursion of dry
air from the north and northeast as well. There is lack of both low level and
upper level support for 30U. SST are around 30C.  General model guidance does
not suggest intensification of 30U. However, if deep convection returns to near
centre then 30U may have a chance to become organised on the weekend.  

Low-level westerly flow is currently steering 30U to the southeast. A mid-level
anticyclone to the southeast is likely to become the more dominant influence on
Saturday resulting in a slow southerly motion and then a turn to the west as
the steering ridge is expected to strengthen over central Australia. This takes
30U towards the eastern Top End coast next week.  

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 18/1930 UTC.

	Time (ACST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	10 pm April 18	tropical low	11.6S	140.3E	45
+6hr	4 am April 19	tropical low	11.8S	140.5E	70
+12hr	10 am April 19	tropical low	11.9S	140.7E	85
+18hr	4 pm April 19	tropical low	12.0S	140.9E	100
+24hr	10 pm April 19	tropical low	12.2S	140.9E	105
+36hr	10 am April 20	tropical low	12.5S	140.6E	145
+48hr	10 pm April 20	tropical low	12.4S	139.6E	180
+60hr	10 am April 21	tropical low	12.1S	138.3E	210
+72hr	10 pm April 21	tropical low	11.6S	136.8E	245

	Time (AEST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	10 pm April 18	tropical low	11.6S	140.3E	45
+6hr	4 am April 19	tropical low	11.8S	140.5E	70
+12hr	10 am April 19	tropical low	11.9S	140.7E	85
+18hr	4 pm April 19	tropical low	12.0S	140.9E	100
+24hr	10 pm April 19	tropical low	12.2S	140.9E	105
+36hr	10 am April 20	tropical low	12.5S	140.6E	145
+48hr	10 pm April 20	tropical low	12.4S	139.6E	180
+60hr	10 am April 21	tropical low	12.1S	138.3E	210
+72hr	10 pm April 21	tropical low	11.6S	136.8E	245

yhh

WTPS31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 002   
   01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   181200Z --- NEAR 11.6S 140.5E
     MOVEMENT PAST SIX HOURS - 115 DEGREES AT 09 KTS
     POSITION ACCURATE TO WITHIN 030 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   REPEAT POSIT: 11.6S 140.5E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   190000Z --- 12.3S 140.9E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 200 DEG/ 02 KTS
    ---
   24 HRS, VALID AT:
   191200Z --- 12.6S 140.8E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 270 DEG/ 03 KTS
    ---
   36 HRS, VALID AT:
   200000Z --- 12.6S 140.2E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 275 DEG/ 05 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   201200Z --- 12.5S 139.2E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 285 DEG/ 07 KTS
    ---
   72 HRS, VALID AT:
   211200Z --- 11.8S 136.3E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 290 DEG/ 09 KTS
    ---
   LONG RANGE OUTLOOK:
    ---
   96 HRS, VALID AT:
   221200Z --- 10.5S 132.8E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 120 HR POSIT: 295 DEG/ 07 KTS
    ---
   120 HRS, VALID AT:
   231200Z --- 9.3S 130.2E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
    ---
REMARKS:
181500Z POSITION NEAR 11.8S 140.6E.
18APR25. TROPICAL CYCLONE 31P (THIRTYONE), LOCATED APPROXIMATELY
566 NM EAST OF DARWIN, AUSTRALIA, HAS TRACKED EAST-SOUTHEASTWARD
AT 09 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 181200Z IS 999 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 181200Z IS 14 FEET.
NEXT WARNINGS AT 182100Z, 190300Z, 190900Z AND 191500Z.//
NNNN

1. WDPS31 PGTW 181500
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 31P (THIRTYONE) WARNING
   
4. NR 002//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 11.6S 140.5E
    
11.    INITIAL INTENSITY: 35 KTS
    
12.    GEOGRAPHIC REFERENCE: 566 NM EAST OF DARWIN, AUSTRALIA
    
13.    MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 09 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 14 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
    
18. CYCLONE 31P WITH A WELL-DEFINED, YET COMPLETELY EXPOSED LOW-LEVEL
    
19. CIRCULATION CENTER (LLCC). THE CONVECTION THAT WAS PREVIOUSLY
    
20. FLARING OVER THE CENTER OF THE SYSTEM HAS DISSIPATED. MODERATE
    
21. NORTHEASTERLY SHEAR CONTINUES TO ACT ON THE SYSTEM AND IS LIKELY
    
22. THE CAUSE FOR THE LACK OF CENTRAL CONVECTION. AN 180901Z F17 SSMIS
    
23. 91 GHZ MICROWAVE IMAGE REVEALED THE LOW-LEVEL STRUCTURE WITH A
    
24. SMALL PATCH OF REMNANT CONVECTION IN THE SOUTHWESTERN PERIPHERY.
    
25. ENVIRONMENTAL ANALYSIS INDICATES THAT 31P IS IN A MARGINAL
    
26. ENVIRONMENT CHARACTERIZED BY WEAK POLEWARD OUTFLOW ALOFT, MODERATE
    
27. (15-20 KTS) VWS, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. THE
    
28. INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
    
29. EXPOSED LLCC IN ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 35
    
30. KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON THE AGENCY DVORAK AND
    
31. OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. LOW CONFIDENCE IS DUE
    
32. IN PART TO THE WEAK APPEARANCE OF THE SYSTEM CONFLICTING WITH THE
    
33. CURRENT INTENSITY ESTIMATES.
    
34. 
    
35. INITIAL WIND RADII BASIS: PERSISTENCE
    
36. 
    
37. CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A NEAR-EQUATORIAL
    
38. RIDGE (NER) EXTENDING TO THE NORTH OF THE SYSTEM.
    
39. 
    
40. AGENCY DVORAK AND AUTOMATED FIXES:
    
41.    PGTW: T2.5 - 35 KTS
    
42.    KNES: T2.0 - 30 KTS
    
43.    ADRM: T2.5 - 35 KTS
    
44.    CIMSS ADT: 35 KTS AT 181140Z
    
45.    CIMSS AIDT: 35 KTS AT 181140Z
    
46.    CIMSS DPRINT: 28 KTS AT 181210Z
    
47.    CIMSS DMINT: 30 KTS AT 180901Z
    
48. 
    
49. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
    
50.    VWS: 15-20 KTS
    
51.    SST: 29-30 CELSIUS
    
52.    OUTFLOW: WEAK POLEWARD
    
53. 
    
54. ANALYSIS CONFIDENCE:
    
55.    INITIAL POSITION: HIGH
    
56.    INITIAL INTENSITY: LOW
    
57.    INITIAL WIND RADII: LOW
    
58. 
    
59. 3. FORECAST REASONING.
    
60. 
    
61. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
    
62. THE FORECAST FROM THE PREVIOUS WARNING.
    
63. 
    
64. FORECAST DISCUSSION: TC 31P IS FORECAST TO TRACK SOUTH-SOUTHEASTWARD
    
65. OVER THE NEXT 12 HOURS BEFORE RIDGING BEGINS TO BUILD IN TO THE
    
66. SOUTHEAST OF THE SYSTEM. AS THE RIDGING BUILDS IN, THE SYSTEM WILL
    
67. BEGIN TO MAKE A SHARP WESTWARD TURN. AS THE RIDGE CONTINUES TO
    
68. BUILD AND PROPAGATES WESTWARD, THE STEERING PATTERN WILL BECOME
    
69. MORE DEFINED, ALLOWING FOR AN INCREASE IN TRACK SPEEDS AS THE
    
70. VORTEX RIDES ALONG THE NORTHERN PERIPHERY OF THE RIDGE THROUGH THE
    
71. END OF THE FORECAST PERIOD. REGARDING INTENSITY, 31P IS EXPECTED TO
    
72. REMAIN IN A MARGINAL ENVIRONMENT DUE TO THE ABSENCE OF A GOOD
    
73. OUTFLOW CHANNEL AND SOME SLIGHT DRY AIR ENTRAINMENT ALONG THE
    
74. WESTERN PERIPHERY. HOWEVER, SHEAR IS EXPECTED TO BEGIN SLIGHTLY
    
75. DECREASING AFTER TAU 24. OVERALL, NO SIGNIFICANT INTENSIFICATION IS
    
76. CURRENTLY EXPECTED THROUGHOUT THE FORECAST PERIOD AT THIS TIME. DUE
    
77. TO THE BORDERLINE 35-KNOT THRESHOLD OF THE SYSTEM, THERE IS A
    
78. POSSIBILITY FOR A DROP TO BELOW THE BASIN WARNING CRITERIA IF THE
    
79. SYSTEM IS UNABLE TO ATTAIN PERSISTENT CONVECTION.
    
80. 
    
81. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
    
82. AGREEMENT WITH ALL MODELS DEPICTING THE SHARP WESTWARD TURN NEAR
    
83. TAU 24. THE ECMWF AND GFS ENSEMBLES ALSO HAVE NO MAJOR SPREAD
    
84. BETWEEN MEMBERS, SUPPORTING THE JTWC TRACK FORECAST. INTENSITY
    
85. GUIDANCE IS IN AGREEMENT THROUGH TAU 96, WITH ALL MODELS SUGGESTING
    
86. A NEARLY STEADY INTENSITY OF AROUND 30-40 KTS. AFTER TAU 96,
    
87. COAMPS-TC BECOMES AN OUTLIER AND SUGGESTS A BOUT OF INTENSIFICATION
    
88. THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE JTWC INTENSITY
    
89. FORECAST IS PLACED WITH MEDIUM CONFIDENCE THROUGH TAU 72 AND LOW
    
90. CONFIDENCE THEREAFTER.
    
91. 
    
92. FORECAST CONFIDENCE:
    
93.    TRACK 0 - 72 HR: HIGH
    
94.    TRACK 72-120 HR: MEDIUM
    
95.    INTENSITY 0 - 72 HR: MEDIUM
    
96.    INTENSITY 72-120 HR: LOW//
    
97. NNNN

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