WPAC: PABUK - Remnants

[Hayabusa]

99W INVEST 241221 0000 8.9N 115.3E WPAC 15 0

[Hayabusa]

TCFA and JMA TC warning since 00z

WTPN21 PGTW 220330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 9.5N 115.3E TO 12.0N 110.7E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 220330Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 9.8N 114.8E. THE SYSTEM IS MOVING WESTWARD AT 05 KNOTS.

2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED AT
9.9N 115.3E IS NOW LOCATED NEAR 9.8N 114.8E, APPROXIMATELY 464 NM SW OF
MANILA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A PERSISTENT
PLUME OF DEEP CONVECTION FLARING ON THE WEST SIDE OF AN AREA OF LOW LEVEL
CONVERGENCE. A 21/2250Z SSMI/S 37 GHZ IMAGE DEPICTS FORMATIVE BANDING
CURVED AROUND THE WESTERN EDGE. VIGOROUS NORTHERLY LOW LEVEL FLOW
THROUGHOUT THE WESTERN SOUTH CHINA SEA IS EXPECTED TO BEGIN WRAPPING
AROUND THE AREA OF LOW PRESSURE ASSOCIATED WITH 99W, ESTABLISHING A LOW
LEVEL CIRCULATION. ANALYSIS REVEALS A FAVORABLE ENVIRONMENT FOR
DEVELOPMENT WITH DIFFLUENCE ALOFT, MODERATE POLEWARD OUTFLOW, LOW TO
MODERATE VERTICAL WIND SHEAR (15-20 KTS), AND WARM SEA SURFACE
TEMPERATURES (28-29C). GLOBAL MODELS ARE COMING INTO GOOD AGREEMENT THAT
99W WILL BECOME THE DOMINANT CENTER OF WHAT HAS BEEN A BROAD AREA OF LOW
PRESSURE THROUGHOUT THE EASTERN SOUTH CHINA SEA, FOREGOING THE
DEVELOPMENT OF THE PREVIOUSLY IDENTIFIED CENTER ASSOCIATED WITH 98W. THE
ENSEMBLES SHOW A GENERALLY SLOW, NORTHWESTWARD MOTION IN THE NEXT 12-36
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 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
230330Z.//
NNNN

TD a
Issued at 2024/12/22 04:10 UTC
Analysis at 12/22 03 UTC
Grade TD
Scale -
Intensity -
Center position N9°30′ (9.5°)
E114°25′ (114.4°)
Direction and speed of movement NW Slow
Central pressure 1004 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 12/23 03 UTC
Grade TS
Intensity -
Center position of probability circle N11°00′ (11.0°)
E113°05′ (113.1°)
Direction and speed of movement NW Slow
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 130 km (70 NM)
Forecast for 12/24 00 UTC
Grade TS
Intensity -
Center position of probability circle N11°10′ (11.2°)
E111°35′ (111.6°)
Direction and speed of movement W Slow
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 12/25 00 UTC
Grade TD
Intensity -
Center position of probability circle N10°55′ (10.9°)
E109°35′ (109.6°)
Direction and speed of movement W Slow
Central pressure 1006 hPa
Radius of probability circle 260 km (140 NM)

[Hayabusa]

WDPN31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 28W (TWENTYEIGHT)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 11.0N 113.2E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 383 NM EAST OF HO CHI MINH CITY, VIETNAM
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CONSOLIDATING SYSTEM, WITH IMPROVED DEEP CONVECTIVE BANDING WRAPPING
FROM THE NORTHERN QUADRANT INTO THE SOUTHERN QUADRANT OF AN IMPROVED
LOW-LEVEL CIRCULATION CENTER (LLCC). TROPICAL DEPRESSION 28W HAS
FORMED SLOWLY WITHIN A COMPLEX, LATE SEASON ENVIRONMENT, ADJACENT TO
A STRONG NORTHEAST SURGE EVENT AND EXTENSIVE SWATH OF 25-30 KNOT
NORTH-NORTHEASTERLY TO NORTHERLY WINDS. INVEST 98W, WHICH FORMED IN
CLOSE PROXIMITY TO THIS SYSTEM, IS WEAKENING RAPIDLY AND GETTING
ABSORBED INTO THE SOUTHEAST PERIPHERY OF 28W. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON EIR IMAGERY. THE INITIAL
INTENSITY OF 25 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY DVORAK ESTIMATES AND THE CIMSS D-PRINT ESTIMATE OF 27 KNOTS.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: LOW-LEVEL SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS
RJTD: T1.5 - 25 KTS
CIMSS D-PRINT: 27 KTS AT 221200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 15-20 KTS
SST: 27-28 CELSIUS
OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 28W IS TRACKING ALONG
THE SOUTHWESTERN PERIPHERY OF THE LOW-LEVEL STR AND IS FORECAST TO
CONTINUE TRACKING NORTHWESTWARD THROUGH TAU 24. MODEST
INTENSIFICATION IS ANTICIPATED THROUGH TAU 24, WITH A PEAK INTENSITY
OF 40 KNOTS FORECAST BY TAU 24 DUE TO MARGINALLY FAVORABLE
CONDITIONS. AFTER TAU 24, THE SYSTEM WILL SLOW AS IT ENCOUNTERS
STRONG LOW-LEVEL SURGE FLOW THEN WILL TURN SHARPLY WEST-SOUTHWESTWARD
WHILE WEAKENING DUE TO SLIGHTLY COOLER SST VALUES (25-26C) AND
INFUSION OF COOLER, MORE STABLE AIR ASSOCIATED WITH THE SURGE EVENT.
AFTER TAU 48, THE SURGE EVENT WILL GRADUALLY WEAKEN ALLOWING THE
SYSTEM TO TRACK WEST-SOUTHWESTWARD INTO SOUTHERN VIETNAM UNDER THE
LOW-LEVEL RIDGE OVER SOUTHEAST ASIA. TD 28W WILL QUICKLY DISSIPATE
OVER VIETNAM BY TAU 72 DUE TO LAND INTERACTION.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH
DETERMINISTIC TRACKERS INDICATING A WESTWARD TO SOUTH-SOUTHWESTWARD
TRACK. THE 220000Z GFS ENSEMBLE (GEFS) SHOWS A SIMILAR SPREAD OF
SOLUTIONS, WITH THE BULK OF THE SOLUTIONS TRACKING THE DISSIPATING
SYSTEM JUST SOUTH OF VIETNAM. THE 220000Z ECMWF ENSEMBLE (EPS)
SUPPORTS A MORE WESTWARD TO WEST-SOUTHWESTWARD TRACK INTO SOUTHERN
VIETNAM. WITH THE EXCEPTION OF HAFS-A, RELIABLE INTENSITY GUIDANCE
SUPPORTS THE JTWC INTENSITY FORECAST WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM//
NNNN

[Hayabusa]

T2426(Pabuk)
Issued at 2024/12/23 07:05 UTC
Analysis at 12/23 06 UTC
Grade TS
Scale -
Intensity -
Center position N11°05′ (11.1°)
E112°30′ (112.5°)
Direction and speed of movement W Slow
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 N440 km (240 NM)
S220 km (120 NM)
Forecast for 12/24 06 UTC
Grade TS
Intensity -
Center position of probability circle N11°00′ (11.0°)
E111°10′ (111.2°)
Direction and speed of movement W Slow
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 95 km (50 NM)
Forecast for 12/25 06 UTC
Grade TD
Intensity -
Center position of probability circle N11°30′ (11.5°)
E109°05′ (109.1°)
Direction and speed of movement W Slow
Central pressure 1008 hPa
Radius of probability circle 155 km (85 NM)