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2025 Global Tropical Cyclone Season Discussion
- Thread starter Atlantic
- Start date
IdaliaHelene
Member
jova
The JTWC's most recent discussion on 31P noted that if it did a loop and moved southwards that it could regenerate:
31P (Tropical Low 30U) is located 628 km east of Darwin, Australia, and has tracked west-northwestward at 20 km/h (11 knots) over the past 6 hours. Maximum significant wave height is 3.4 meters (11 feet).
31P is moving northwestward at a steady speed of around 20 km/h (10 knots), along the northern side of a low- to mid-level ridge situated over northern Australia.
No significant change is expected in the overall steering pattern through the forecast period, other than a general weakening of the steering gradient after 24 hours which will cause 31P to slow down slightly towards the end of the forecast.
The system is currently passing over guluwuru and raragala islands and will soon emerge into the arafura sea. The northwestward track means the system will move further away from land as times goes on.
Shear is forecast to steadily decrease over the next 24 to 36 hours, and as the system moves further away from land and frictional effects lessen, both the HAFS-A and GFS show a short period of vortex alignment and intensification. However, as the system moves further equatorward, it moves into a more hostile shear regime and will rapidly weaken below warning threshold in 2 days. However, there is a possibility of regeneration if the system loops back to the south as several of the models suggest.
Deterministic track guidance is in good agreement over the next 2 days, with all consensus members except the NAVGEM, confined to a very tight envelope of just 93 km.
Along-track uncertainty remains much higher, with the ECMWF and the ECENS mean outpacing the other models, pushing out ahead of the pack by about 185 km in 2 days.
The JTWC forecast is placed on the northern edge of the guidance envelope, close to the consensus mean, with high confidence. Intensity guidance remains mixed, though all models agree on the system intensifying in around 24 hours, peaking in around 36 hours then weakening again.
The main exception is the SHIPS-GFS which shows the system steadily intensifying through the forecast period.
The JTWC forecast is placed amongst the tightest packing of models and the consensus mean, with medium confidence.
Warning Number 14. Information provided by the Joint Typhoon Warning Center (JTWC).
- Messages
- 2,828
- Location
- Smithville MS
The Canadian and Euro have nothing. We'll see. We will be up to 126 consecutive days by then.
Just sitting back and watching 31P continue to struggle. It has a good environment with ample moisture and low (16 kts) of wind shear. The problem is dry air in proximity to it.
The BoM noted this on 31P (30U for them):
"An upper-level trough that passes to the south on the weekend may provide
another opportunity for 30U to strengthen as shear reduces again."
The BoM noted this on 31P (30U for them):
"An upper-level trough that passes to the south on the weekend may provide
another opportunity for 30U to strengthen as shear reduces again."
The BoM just released their 13:00 UTC time bulletin on 30U/31P, I have a feeling we will be watch 30U/31P for a while.
IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 1320 UTC 22/04/2025
Name: Tropical Low
Identifier: 30U
Data At: 1200 UTC
Latitude: 10.0S
Longitude: 133.1E
Location Accuracy: within 30nm (55 km)
Movement Towards: west northwest (289 deg)
Speed of Movement: 9 knots (17 km/h)
Maximum 10-Minute Wind: 30 knots (55 km/h)
Maximum 3-Second Wind Gust: 45 knots (85 km/h)
Central Pressure: 1005 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: T1.5/2.0/S0.0/24HRS STT:W0.5/06HRS
Pressure of outermost isobar: 1009 hPa
Radius of outermost closed isobar: 80 nm (150 km)
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
(UTC) : degrees : nm (km): knots(km/h): hPa
+06: 22/1800: 9.8S 132.2E: 040 (080): 030 (055): 1005
+12: 23/0000: 9.4S 131.5E: 050 (095): 030 (055): 1004
+18: 23/0600: 8.8S 131.0E: 060 (110): 030 (055): 1004
+24: 23/1200: 8.5S 130.9E: 065 (120): 030 (055): 1003
+36: 24/0000: 8.1S 131.0E: 080 (150): 030 (055): 1002
+48: 24/1200: 8.2S 131.2E: 095 (180): 025 (045): 1005
+60: 25/0000: 8.9S 131.7E: 110 (200): 025 (045): 1006
+72: 25/1200: 9.4S 132.6E: 130 (240): 025 (045): 1006
+96: 26/1200: 10.2S 133.5E: 165 (305): 025 (045): 1006
+120: 27/1200: 10.8S 132.7E: 200 (370): 025 (045): 1005
REMARKS:
Tropical Low 30U is moving northwest in the Arafura Sea. Deep convection has
weakened, and no organisation of deep cloud is evident.
Position based on radar and animated satellite imagery with moderate
confidence.
Dvorak analysis: As the deep convection has weakened, there is no longer a
suitable Dvorak pattern to apply to the current satellite imagery. MET is 1.5
based on a 24 hour S trend, with no adjustment. FT is 1.5 based on MET with CI
held at 2.0 for initial weakening and for the potential convection
redevelopment that could occur with the diurnal maximum over the next 6 to 12
hours. Objective guidance at 1200 UTC (1 minute means): ADT 41 kn, AiDT 35 kn,
DPRINT 28 kn, D-MINT 24 kn (0947 UTC), SATCON 40 kn. Intensity is set at 30 kn
based on earlier scatterometry and a strong consensus of intensity guidance
indicating a 30-knot wind maxima in the southwest quadrant.
Environmental conditions are marginally favourable. SSTs are 28-29C along the
forecast track, there is ample atmospheric moisture and an upper trough to the
south enhancing poleward outflow. CIMSS analysed shear at 1200 UTC is 17 kn
from the east however, and is expected to increase further. With the lack of
organisation and deep convection currently observed it is unlikely there will
be sufficient opportunity for 30U to intensify into a tropical cyclone before
the increasing shear and decreasing Coriolis makes the environment unfavourable
for development.
A low to mid-level anticyclone is steering 30U to the northwest. Strengthening
upper-level easterlies on Thursday will cause 30U to become a shallower system
that then moves back towards the southeast on Friday under the influence of a
mid-level trough passing to the south.
An upper-level trough that passes to the south on the weekend may provide
another opportunity for 30U to strengthen as shear reduces again.
Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 22/1930 UTC.
IDD20020
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - NORTHERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 1320 UTC 22/04/2025
Name: Tropical Low
Identifier: 30U
Data At: 1200 UTC
Latitude: 10.0S
Longitude: 133.1E
Location Accuracy: within 30nm (55 km)
Movement Towards: west northwest (289 deg)
Speed of Movement: 9 knots (17 km/h)
Maximum 10-Minute Wind: 30 knots (55 km/h)
Maximum 3-Second Wind Gust: 45 knots (85 km/h)
Central Pressure: 1005 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: T1.5/2.0/S0.0/24HRS STT:W0.5/06HRS
Pressure of outermost isobar: 1009 hPa
Radius of outermost closed isobar: 80 nm (150 km)
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
(UTC) : degrees : nm (km): knots(km/h): hPa
+06: 22/1800: 9.8S 132.2E: 040 (080): 030 (055): 1005
+12: 23/0000: 9.4S 131.5E: 050 (095): 030 (055): 1004
+18: 23/0600: 8.8S 131.0E: 060 (110): 030 (055): 1004
+24: 23/1200: 8.5S 130.9E: 065 (120): 030 (055): 1003
+36: 24/0000: 8.1S 131.0E: 080 (150): 030 (055): 1002
+48: 24/1200: 8.2S 131.2E: 095 (180): 025 (045): 1005
+60: 25/0000: 8.9S 131.7E: 110 (200): 025 (045): 1006
+72: 25/1200: 9.4S 132.6E: 130 (240): 025 (045): 1006
+96: 26/1200: 10.2S 133.5E: 165 (305): 025 (045): 1006
+120: 27/1200: 10.8S 132.7E: 200 (370): 025 (045): 1005
REMARKS:
Tropical Low 30U is moving northwest in the Arafura Sea. Deep convection has
weakened, and no organisation of deep cloud is evident.
Position based on radar and animated satellite imagery with moderate
confidence.
Dvorak analysis: As the deep convection has weakened, there is no longer a
suitable Dvorak pattern to apply to the current satellite imagery. MET is 1.5
based on a 24 hour S trend, with no adjustment. FT is 1.5 based on MET with CI
held at 2.0 for initial weakening and for the potential convection
redevelopment that could occur with the diurnal maximum over the next 6 to 12
hours. Objective guidance at 1200 UTC (1 minute means): ADT 41 kn, AiDT 35 kn,
DPRINT 28 kn, D-MINT 24 kn (0947 UTC), SATCON 40 kn. Intensity is set at 30 kn
based on earlier scatterometry and a strong consensus of intensity guidance
indicating a 30-knot wind maxima in the southwest quadrant.
Environmental conditions are marginally favourable. SSTs are 28-29C along the
forecast track, there is ample atmospheric moisture and an upper trough to the
south enhancing poleward outflow. CIMSS analysed shear at 1200 UTC is 17 kn
from the east however, and is expected to increase further. With the lack of
organisation and deep convection currently observed it is unlikely there will
be sufficient opportunity for 30U to intensify into a tropical cyclone before
the increasing shear and decreasing Coriolis makes the environment unfavourable
for development.
A low to mid-level anticyclone is steering 30U to the northwest. Strengthening
upper-level easterlies on Thursday will cause 30U to become a shallower system
that then moves back towards the southeast on Friday under the influence of a
mid-level trough passing to the south.
An upper-level trough that passes to the south on the weekend may provide
another opportunity for 30U to strengthen as shear reduces again.
Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 22/1930 UTC.
IRL, this is 31P or 31S/30U
The JTWC has issued their final warning on 31S/31P or 30U. They originally issued the 18th warning still calling it a TC, but further satellite imagery shortly after the warning was issued revealing that the storms structure had degraded very much and that the storm fell below the JTWC's warning threshold, this was based on a MetOp-B ASCAT pass and the animated shortwave infrared imagery.
WTXS31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 018A AMENDED//
RMKS/
1. TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 018A AMENDED
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
221200Z --- NEAR 10.0S 133.2E
MOVEMENT PAST SIX HOURS - 290 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
REPEAT POSIT: 10.0S 133.2E
---
FORECASTS:
12 HRS, VALID AT:
230000Z --- 9.3S 131.9E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
221500Z POSITION NEAR 9.8S 132.9E.
22APR25. TROPICAL CYCLONE 31P (THIRTYONE), LOCATED APPROXIMATELY
202 NM NORTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED WEST-
NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. AFTER RELEASE OF
THE ORIGINAL WARNING NUMBER EIGHTEEN (WR 018), FURTHER SATELLITE
ANALYSIS REVEALED SIGNIFICANTLY DECAYED CONVECTIVE STRUCTURE OF THE
SYSTEM, WITH SURFACE WINDS BELOW WARNING THRESHOLD. THE PGTW DVORAK
ESTIMATE IS NOW 1.5 AND MAJORITY OF THE DETERMINISTIC AND ENSEMBLE
GUIDANCE AGREES ON FURTHER DECAY OF TC 31P. THIS IS THE FINAL
WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI.
THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.
MINIMUM CENTRAL PRESSURE AT 221200Z IS 1007 MB. MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 221200Z IS 18 FEET.
2. JUSTIFICATION FOR AMENDMENT: FORECAST TRUNCATED TO 12 HOURS AND
SYSTEM FINAL WARNED BASED ON 221230Z METOP-B ASCAT PASS AND THE
ANIMATED SHORTWAVE INFRARED IMAGERY.//
NNNN
WTXS31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 018A AMENDED//
RMKS/
1. TROPICAL CYCLONE 31P (THIRTYONE) WARNING NR 018A AMENDED
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
221200Z --- NEAR 10.0S 133.2E
MOVEMENT PAST SIX HOURS - 290 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
REPEAT POSIT: 10.0S 133.2E
---
FORECASTS:
12 HRS, VALID AT:
230000Z --- 9.3S 131.9E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
221500Z POSITION NEAR 9.8S 132.9E.
22APR25. TROPICAL CYCLONE 31P (THIRTYONE), LOCATED APPROXIMATELY
202 NM NORTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED WEST-
NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. AFTER RELEASE OF
THE ORIGINAL WARNING NUMBER EIGHTEEN (WR 018), FURTHER SATELLITE
ANALYSIS REVEALED SIGNIFICANTLY DECAYED CONVECTIVE STRUCTURE OF THE
SYSTEM, WITH SURFACE WINDS BELOW WARNING THRESHOLD. THE PGTW DVORAK
ESTIMATE IS NOW 1.5 AND MAJORITY OF THE DETERMINISTIC AND ENSEMBLE
GUIDANCE AGREES ON FURTHER DECAY OF TC 31P. THIS IS THE FINAL
WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI.
THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.
MINIMUM CENTRAL PRESSURE AT 221200Z IS 1007 MB. MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 221200Z IS 18 FEET.
2. JUSTIFICATION FOR AMENDMENT: FORECAST TRUNCATED TO 12 HOURS AND
SYSTEM FINAL WARNED BASED ON 221230Z METOP-B ASCAT PASS AND THE
ANIMATED SHORTWAVE INFRARED IMAGERY.//
NNNN
Last edited:
As 31S or 31P/30U has disspated according to the JTWC, I will be enacting a two week break on tropical weather. If possible, could you provide updates on tropical weather around the world during that time frame on this thread, and the 2025 AHS thread as well, @IdaliaHelene?
If everything goes well, I will return to the tropical weather area on May 7th.
Edit: I will return May 7th actually.
If everything goes well, I will return to the tropical weather area on May 7th.
Edit: I will return May 7th actually.
This break will begin tomorrow, April 23rd.
IdaliaHelene
Member
pat pat
I will bro
I just need a break, as with a few exceptions of some quiet days, I have been constantly tracking the tropics since about October 2023. So I am taking a break to recoperate, get into the midspace and prepare for the NHEM's cyclone season. Nothing's wrong, I'm just tired and I have been planning to take a break from about a month or two, I was just waiting for a quiet time in the tropics.
Ping me when May 7th arrives here on this thread, please. @IdaliaHelene
Breaking my silence during my break to share this I found:
Ams.Confex.Com.
https://ams.confex.com › Handout › Paper441948
This tells about the process that the JTWC does to review and produce the best track on every storm they track each year.
Now I shall return to my break.
The Joint Typhoon Warning Center Tropical Cyclone Best ...
Ams.Confex.Com.
https://ams.confex.com › Handout › Paper441948
This tells about the process that the JTWC does to review and produce the best track on every storm they track each year.
Now I shall return to my break.
