WPAC: MUN - Post-Tropical - Discussion

[Hayabusa]

90W INVEST 250630 0000 16.0N 149.5E WPAC 15 1006

[StormWeather]

90W INVEST 250630 0000 16.0N 149.5E WPAC 15 1006

This came from literally nowhere. I was not expecting this.

[Hayabusa]

90W INVEST 250630 0000 16.0N 149.5E WPAC 15 1006

This came from literally nowhere. I was not expecting this.

I think 99W was supposed to develop but models delayed it to 90W

[cycloneye]

First discussion from JTWC for this one.

AN AREA OF CONVECTION (INVEST 90W) HAS PERSISTED NEAR 21.4N
148.2E, APPROXIMATELY 504 NM SOUTHEAST OF IWO TO. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 301600Z AMSR2 89 GHZ IMAGE
DEPICT A POORLY ORGANIZED LOW LEVEL CIRCULATION CENTER (LLCC) OBSCURED
BY FLARING CONVECTION ALONG THE EASTERN PERIPHERY. ENVIRONMENTAL
ANALYSIS FOR THE AREA INDICATES MARGINALLY FAVORABLE CONDITIONS FOR
DEVELOPMENT WITH LOW TO MODERATE (15-20 KTS) SOUTHERLY VERTICAL WIND
SHEAR OFFSET BY WARM (29-30C) SEA SURFACE TEMPERATURES AND STRONG
POLEWARD OUTFLOW ALOFT. A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT)
CELL TO THE WEST OF THE LLCC IS THE MAIN CAUSE OF THE ELEVATED SHEAR
ON THE SYSTEM. GLOBAL DETERMINISTIC AND ENSEMBLE MODELS ARE IN FAIR
AGREEMENT THAT 90W WILL CONTINUE NORTH-NORTHWESTWARD WITH MARGINAL
DEVELOPMENT OVER THE NEXT COUPLE OF DAYS WITH THE POTENTIAL FOR THE
FORMATION OF A MONSOON DEPRESSION. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

[cycloneye]

THE AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED NEAR
21.1N 148.2E IS NOW LOCATED NEAR 22.5N 148.2E, APPROXIMATELY 400 NM
EAST-SOUTHEAST OF IWO TO. MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A
010518Z SSMIS F18 91 GHZ IMAGE DEPICT A CONSOLIDATING LOW LEVEL
CIRCULATION CENTER (LLCC) OBSCURED BY DEEP CONVECTION ALONG THE
NORTHEASTERN PERIPHERY. ENVIRONMENTAL ANALYSIS FOR THE AREA INDICATES
MARGINALLY FAVORABLE CONDITIONS FOR DEVELOPMENT WITH WARM (29-30 C)
SEA SURFACE TEMPERATURES AND STRONG POLEWARD OUTFLOW ALOFT, OFFSET BY
MODERATE (15-20 KTS) SOUTHERLY VERTICAL WIND SHEAR, AS RELATIVELY DRY
AIR ASSOCIATED WITH A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL
TO THE WEST-SOUTHWEST OF THE SYSTEM. GLOBAL DETERMINISTIC AND ENSEMBLE
MODELS ARE IN GOOD AGREEMENT THAT 90W WILL CONTINUE NORTH-
NORTHWESTWARD WITH GRADUAL DEVELOPMENT OVER THE NEXT 48 HOURS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
IS UPGRADED TO MEDIUM.

[Hayabusa]

JMA TD 06Z

WWJP27 RJTD 010600
WARNING AND SUMMARY 010600.
WARNING VALID 020600.
TROPICAL DEPRESSION 1008 HPA AT 22N 148E NW SLOWLY.

[Hayabusa]

TC warning

TD a
Issued at 2025/07/01 13:30 UTC
Analysis at 07/01 12 UTC
Grade TD
Scale -
Intensity -
Center position N22°35′ (22.6°)
E148°10′ (148.2°)
Direction and speed of movement NW Slow
Central pressure 1006 hPa
Maximum wind speed 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 07/02 12 UTC
Grade TS
Intensity -
Center position of probability circle N25°50′ (25.8°)
E145°40′ (145.7°)
Direction and speed of movement NNW 15 km/h (9 kt)
Central pressure 1002 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 130 km (70 NM)
Forecast for 07/03 12 UTC
Grade TS
Intensity -
Center position of probability circle N28°05′ (28.1°)
E144°10′ (144.2°)
Direction and speed of movement NNW 15 km/h (7 kt)
Central pressure 1000 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 200 km (110 NM)
Forecast for 07/04 12 UTC
Grade TS
Intensity -
Center position of probability circle N29°55′ (29.9°)
E144°35′ (144.6°)
Direction and speed of movement N Slow
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 260 km (140 NM)
Forecast for 07/05 12 UTC
Grade TS
Intensity -
Center position of probability circle N30°35′ (30.6°)
E146°00′ (146.0°)
Direction and speed of movement ENE Slow
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 330 km (180 NM)
Forecast for 07/06 12 UTC
Grade TS
Intensity -
Center position of probability circle N31°05′ (31.1°)
E147°10′ (147.2°)
Direction and speed of movement ENE Slow
Central pressure 992 hPa
Maximum sustained wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 440 km (240 NM)

[cycloneye]

TCFA issued.

WTPN21 PGTW 011400
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90W)//
RMKS/
1.FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
130 NM EITHER SIDE OF A LINE FROM 22.1N 145.9E TO 23.5N 150.3E
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 25 TO 30 KTS. ASCAT-C IMAGERY
AT 011301Z INDICATES THAT A CONSOLIDATING CIRCULATION CENTER IS LOCATED
NEAR 23.2N 147.9E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED
NEAR 21.4N 148.2E IS NOW LOCATED NEAR 23.2N 147.9E, APPROXIMATELY 373 NM
EAST-SOUTHEAST OF IWO TO. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
AND A 010948Z GMI 89 GHZ IMAGE DEPICT A CONSOLIDATING LOW LEVEL
CIRCULATION CENTER (LLCC) OBSCURED BY DEEP CONVECTION ALONG THE NORTH
AND EASTERN PERIPHERIES. ENVIRONMENTAL ANALYSIS FOR THE AREA INDICATES
MARGINALLY FAVORABLE CONDITIONS FOR DEVELOPMENT WITH WARM (29-30 C) SEA
SURFACE TEMPERATURES AND STRONG POLEWARD OUTFLOW ALOFT, OFFSET BY
MODERATE (15-20 KTS) SOUTHERLY VERTICAL WIND SHEAR, AS RELATIVELY DRY
AIR ASSOCIATED WITH A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO
THE WEST-SOUTHWEST OF THE SYSTEM. GLOBAL DETERMINISTIC AND ENSEMBLE
MODELS ARE IN GOOD AGREEMENT THAT 90W WILL CONTINUE NORTH-NORTHWESTWARD
WITH GRADUAL DEVELOPMENT OVER THE NEXT 24-48 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KTS. MINIMUM SEA LEVEL PRESSURE
IS ESTIMATED TO BE NEAR 1007 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
021400Z.
//
NNNN

[cycloneye]

JTWC upgrades to TD 04W.

[cycloneye]

JMA still as TD.

Issued at 2025/07/02 01:30 UTC
Analysis at 07/02 00 UTC
Grade TD
Scale -
Intensity -
Center position N24°30′ (24.5°)
E147°30′ (147.5°)
Direction and speed of movement NNW 15 km/h (7 kt)
Central pressure 1006 hPa
Maximum wind speed 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

[cycloneye]

FORECAST DISCUSSION: TD 04W IS FORECAST TO CONTINUE ON A
NORTH-NORTHWESTERLY TRACK ALONG THE WESTERN PERIPHERY OF THE STR
THROUGH TAU 48. AFTER TAU 48, RIDGING TO THE WEST WILL BUILD AND
PULL THE VORTEX TOWARD THE NORTHEAST THROUGH THE REMAINDER OF THE
FORECAST PERIOD. REGARDING INTENSITY, 04W IS FORECAST TO STEADILY
INTENSIFY TO A PEAK INTENSITY OF 55 KTS AT TAU 72 DUE TO THE
OVERALL CONDUCIVE ENVIRONMENT. THE SYSTEM WILL CONTINUE TO DISTANCE
ITSELF FROM THE TUTT CELL, WHICH WILL ALLOW FOR IMPROVEMENTS TO THE
EQUATORWARD OUTFLOW CHANNEL AS THE SYSTEM GAINS LATITUDE. AFTER TAU
72, SEA SURFACE TEMPERATURES WILL BEGIN TO COOL, PUTTING A HALT TO
FURTHER INTENSIFICATION. AND BY TAU 120, SEA TEMPERATURES ARE
EXPECTED TO DROP TO AROUND 25 C, WHICH WILL INITIATE A WEAKENING
TREND. ADDITIONALLY, AN UPPER-LEVEL TROUGH IS FORECAST TO PROPAGATE
EASTWARD AND BEGIN INTERACTING WITH THE SYSTEM NEAR TAU 120.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 72 WITH THE EXCEPTIONS OF NAVGEM AND GALWEM.
NAVGEM HAS A MUCH FASTER TRACK SPEED AND GALWEM HAS THE VORTEX
MAKING A SHARP EASTWARD TURN NEAR TAU 48. DISCOUNTING THE TWO
OUTLIERS, THERE IS A 100 NM CROSS-TRACK SPREAD AT TAU 72. AFTER TAU
72, GFS STARTS TO BECOME AN OUTLIER AS IT ACTUALLY HAS THE VORTEX
MAKING A TURN WESTWARD AFTER TAU 96 AS IT GETS CAUGHT UNDERNEATH
RIDGING TO THE NORTH. THE TRACK SPEED OF THE SYSTEM WILL LIKELY
DICTATE WHETHER IT WILL GET CAUGHT AND PULLED WESTWARD (SLOW) OR
MOVE OFF TO THE NORTHEAST (FAST). THE JTWC TRACK FORECAST CURRENTLY
HAS THE NORTHEASTWARD TRACK AS THAT IS WHAT THE MAJORITY OF
CONSENSUS DEPICTS. INTENSITY GUIDANCE IS IN MODERATE AGREEMENT WITH
MOST MODELS HAVING THE PEAK INTENSITY FROM 50-60 KTS AT TAU 84-96.
COAMPS-TC (GFS BASED) SUGGESTS A HIGHER PEAK OF AROUND 85 KTS.
OVERALL, THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH MEDIUM CONFIDENCE.

[cycloneye]

FORECAST DISCUSSION: TD 04W IS FORECAST TO CONTINUE TRACKING
NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL
RIDGE THROUGH TAU 48. NEAR TAU 48, RIDGING TO THE WEST WILL BUILD
AND PULL THE VORTEX TOWARD THE NORTHEAST THROUGH THE REMAINDER OF
THE FORECAST PERIOD. REGARDING INTENSITY, 04W IS FORECAST TO
MARGINALLY INTENSIFY OVER THE NEXT 24 HOURS AS THE TUTT CELL
CONTINUES TO AFFECT THE VORTEX, HINDERING DEVELOPMENT. AFTER TAU
24, THE SYSTEM WILL HAVE SUFFICIENTLY DISTANCED ITSELF FROM THE
TUTT CELL WHICH WILL ALLOW FOR FURTHER INTENSIFICATION AS SHEAR
DROPS TO AROUND 5-10 KTS. A PEAK INTENSITY OF 55 KTS IS FORECAST TO
OCCUR NEAR TAU 72-96. AFTER TAU 96, SEA SURFACE TEMPERATURES WILL
BEGIN TO COOL, HALTING ANY FURTHER INTENSIFICATION. BY TAU 120, SEA
TEMPERATURES ARE EXPECTED TO DROP TO AROUND 25 C, WHICH WILL
INITIATE A WEAKENING TREND. ADDITIONALLY, AN UPPER-LEVEL TROUGH
WILL PROPAGATE EASTWARD AND BEGIN INTERACTING WITH THE SYSTEM
AROUND TAU 120, CAUSING SHEAR TO DRAMATICALLY INCREASE IN THE
EXTENDED FORECAST.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 72 WITH A 120 NM CROSS-TRACK SPREAD AT TAU
72. AFTERWARD, MODELS SIGNIFICANTLY DIVERGE DUE TO DIFFERING
INTERACTIONS WITH THE UPPER-LEVEL TROUGH. GFS DETERMINISTIC HAS THE
SYSTEM TURN NORTHWESTWARD VICE NORTHEASTWARD AFTER TAU 96 AS THE
VORTEX GETS CAUGHT UNDERNEATH RIDGING TO THE NORTH. HOWEVER, THE
MAJORITY OF ENSEMBLE MEMBERS SHOW THE NORTHEASTWARD TRACK.
THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL
CONSENSUS THROUGH TAU 96 AND THEN SLIGHTLY TO THE EAST THROUGH TAU
120. INTENSITY GUIDANCE IS IN MODERATE AGREEMENT WITH HAFS-A AND
GFS BEING THE LEAST AGGRESSIVE WHILE COAMPS-TC (GFS BASED) IS THE
MOST AGGRESSIVE MODEL WITH A PEAK INTENSITY OF 80 KTS AT TAU 84.
THE JTWC INTENSITY FORECAST IS PLACED IN LINE WITH THE CONSENSUS
THROUGHOUT THE FORECAST PERIOD WITH MEDIUM CONFIDENCE.

[cycloneye]

JMA has not upgraded to Tropical Storm but JTWC did so.

REMARKS:
021500Z POSITION NEAR 26.5N 146.1E.
02JUL25. TROPICAL STORM 04W (FOUR), LOCATED APPROXIMATELY 226 NM
EAST-SOUTHEAST OF CHICHI JIMA, HAS TRACKED NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 021200Z IS 1002 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 021200Z IS 15 FEET. NEXT WARNINGS AT
022100Z, 030300Z, 030900Z AND 031500Z.

[Hurricane2022]

JMA has not upgraded to Tropical Storm but JTWC did so.

REMARKS:
021500Z POSITION NEAR 26.5N 146.1E.
02JUL25. TROPICAL STORM 04W (FOUR), LOCATED APPROXIMATELY 226 NM
EAST-SOUTHEAST OF CHICHI JIMA, HAS TRACKED NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 021200Z IS 1002 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 021200Z IS 15 FEET. NEXT WARNINGS AT
022100Z, 030300Z, 030900Z AND 031500Z.

https://i.imgur.com/0uXflv1.gif

JTWC isn't a official agency in the WP Basin, so 04W will be officially a TD until JMA upgrades it

[cycloneye]

JMA has not upgraded to Tropical Storm but JTWC did so.

REMARKS:
021500Z POSITION NEAR 26.5N 146.1E.
02JUL25. TROPICAL STORM 04W (FOUR), LOCATED APPROXIMATELY 226 NM
EAST-SOUTHEAST OF CHICHI JIMA, HAS TRACKED NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 021200Z IS 1002 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 021200Z IS 15 FEET. NEXT WARNINGS AT
022100Z, 030300Z, 030900Z AND 031500Z.

https://i.imgur.com/0uXflv1.gif

JTWC isn't a official agency in the WP Basin, so 04W will be officially a TD until JMA upgrades it

Yes I know that. That is why did not add the name Mun to the title.

[cycloneye]

Hurricane2022, yes!!

T2503(Mun)
Issued at 2025/07/02 19:10 UTC
Analysis at 07/02 18 UTC
Grade TS
Scale -
Intensity -
Center position N26°50′ (26.8°)
E145°35′ (145.6°)
Direction and speed of movement NW 20 km/h (10 kt)
Central pressure 1002 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of 30-kt wind area NE330 km (180 NM)
SW220 km (120 NM)

[cycloneye]

REMARKS:
022100Z POSITION NEAR 27.1N 145.5E.
02JUL25. TROPICAL STORM 04W (MUN), LOCATED APPROXIMATELY 593 NM
SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWESTWARD AT
09 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 021800Z IS 1000 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 021800Z IS 15 FEET. NEXT WARNINGS AT
030300Z, 030900Z, 031500Z AND 032100Z.//
NNNN

[cycloneye]

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL STORM 04W (MUN) WARNING NR 005//
RMKS/
1. TROPICAL STORM 04W (MUN) WARNING NR 005


REMARKS:
022100Z POSITION NEAR 27.1N 145.5E.
02JUL25. TROPICAL STORM 04W (MUN), LOCATED APPROXIMATELY 593 NM
SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWESTWARD AT
09 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 021800Z IS 1000 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 021800Z IS 15 FEET. NEXT WARNINGS AT
030300Z, 030900Z, 031500Z AND 032100Z.//
NNNN

[cycloneye]

04W MUN 250703 0000 27.0N 145.4E WPAC 45 992

[cycloneye]