WPAC: SANBA - Post-Tropical

[Hayabusa]

99W INVEST 231014 0600 12.0N 113.4E WPAC 15 0

[Hayabusa]

ABPW10 PGTW 150600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/150600Z-160600ZOCT2023//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR 14.5N
112.4E, APPROXIMATELY 260 NM EAST-SOUTHEAST OF DANANG, VIETNAM. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD AREA OF TURNING SOUTH-
SOUTHEAST OF A CONVERGING CONVECTIVE BOUNDARY JUST SOUTH OF HAINAN. A
150218Z METOP-C ASCAT PARTIAL-PASS SHOWS STRONGER UNASSOCIATED WINDS
(25-30 KTS) ALONG THE NORTHERN PERIPHERY OF 99W, WITH THE LOW LEVEL
CIRCULATION SURROUNDED BY 10-15 KNOT WINDS. ENVIRONMENTAL ANALYSIS
INDICATE THAT 99W IS IN A FAVORABLE AREA FOR DEVELOPMENT WITH LOW (5-10
KTS) VERTICAL WIND SHEAR, GOOD POLEWARD OUTFLOW ALOFT, AND WARM (28-29C)
SEA SURFACE TEMPERATURES. GLOBAL ENSEMBLE MODELS AND THE GFS
DETERMINISTIC MODEL HAVE 99W SLOWLY DEVELOPING OVER THE NEXT 48 HOURS AS
IT NEARS THE CONVERGENT BOUNDARY TO THE NORTH OF THE LLCC. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. 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 LOW.
(2) NO OTHER SUSPECT AREAS.
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: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
NNNN

[Hayabusa]

ABPW10 PGTW 160600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/160600Z-170600ZOCT2023//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR
14.5N 112.4E IS NOW LOCATED NEAR 14.6N 110.9E, APPROXIMATELY 220 NM
EAST-SOUTHEAST OF HUE, VIETNAM. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A BROAD AREA OF TURNING SOUTH OF HAINAN, PARTIALLY OBSCURED BY
DEEP CONVECTION ALONG THE NORTH-NORTHWESTERN PERIPHERY. A 160245Z METOP-
B ASCAT BULLSEYE PASS REVEALS A LOW-LEVEL CIRCULATION SURROUNDED BY 10-
15 KNOT WINDS WITH AN UNASSOCIATED SWATH OF STRONGER 20-25 KNOT WINDS
OFFSET TO THE NORTHERN PERIPHERY OF 99W. ENVIRONMENTAL ANALYSIS INDICATE
THAT 99W IS IN A FAVORABLE AREA FOR DEVELOPMENT WITH LOW (5-10 KTS)
VERTICAL WIND SHEAR, GOOD POLEWARD OUTFLOW ALOFT, AND WARM (28-29C) SEA
SURFACE TEMPERATURES. GLOBAL NUMERICAL MODELS INDICATE THAT 99W WILL
GRADUALLY DEVELOP AS IT REMAINS MOSTLY QUASI-STATIONARY OVER THE NEXT
24-36 HOURS BEFORE TRACKING NORTH-NORTHWESTWARD. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1006 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.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
NNNN

[Hayabusa]

tcfa

WTPN21 PGTW 162030
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 125 NM
EITHER SIDE OF A LINE FROM 15.1N 111.0E TO 18.0N 108.3E 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 15 TO 20 KNOTS. METSAT IMAGERY AT 161800Z INDICATES THAT A
CIRCULATION CENTER IS LOCATED NEAR 15.3N 110.9E. THE SYSTEM IS MOVING
NORTH-NORTHWESTWARD AT 03 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR
14.6N 110.9E IS NOW LOCATED NEAR 15.3N 110.9E, APPROXIMATELY 161 NM
EAST-SOUTHEAST OF DANANG, VIETNAM. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND A 161746Z ATMS 88.2 GHZ MICROWAVE IMAGE DEPICT A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH FLARING DEEP CONVECTION
IN THE WESTERN PERIPHERY AND WEAK FORMATIVE BANDING WRAPPING INTO THE
LLCC FROM THE NORTH. ENVIRONMENTAL ANALYSIS INDICATES THAT 99W IS IN A
FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH ROBUST POLEWARD OUTFLOW
ALOFT, LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR, AND WARM (28-29
C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT
99W WILL TRACK NORTH-NORTHWESTWARD AND CONTINUE TO DEVELOP OVER THE NEXT
24-48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
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
172030Z.//
NNNN

[Hayabusa]

TD a
Issued at 2023/10/17 04:05 UTC
Analysis at 10/17 03 UTC
Grade TD
Scale -
Intensity -
Center position N15°40′ (15.7°)
E110°30′ (110.5°)
Direction and speed of movement W Slow
Central pressure 1008 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

[Hayabusa]

WDPN31 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 16.3N 109.9E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 94 NM EAST OF DA NANG, VIETNAM
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A RAGGED
DEVELOPING SYSTEM IN THE SOUTH CHINA SEA WITH FLARING CONVECTION
NEAR THE CENTRAL DENSE OVERCAST (CDO) AND A FRAGMENTED FORMATIVE
BAND LOOSELY WRAPPING TOWARD THE CDO THAT IS OBSCURING THE LOW
LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A WEAK BUT DISCERNIBLE MICROWAVE LLC IN THE
171019Z SSMIS 91GHZ COLORED IMAGE. THE INITIAL INTENSITY OF 25KTS
IS BASED ON THE DVORAK ESTIMATES OF T1.5 FROM PGTW, KNES, AND RJTD
AND SUPPORTED BY A 170900Z SHIP OBSERVATION 150NM TO THE NORTHWEST.
ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VWS
AND WARM SST TEMPERED BY WEAK RADIAL OUTFLOW AND PROXIMITY TO LAND.

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

CURRENT STEERING MECHANISM: LOW REFLECTION OF A SUBTROPICAL RIDGE
(STR) TO THE EAST-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS
RJTD: T1.5 - 25 KTS
KNES: T1.5 - 25 KTS
DEMS: T1.0 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: WEAK RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: UNDER THE STEERING INFLUENCE OF THE STR TO THE
ENE, TD 16W WILL CONTINUE TO TRACK NORTHWESTWARD TOWARD THE GULF OF
TONKIN. AFTER TAU 48, A SECONDARY, SHALLOW STR APPROACHING FROM THE
WEST WILL COMPETE FOR STEERING AND FORCE THE CYCLONE IN A
QUASI-STATIONARY (QS) MODE BEFORE SLOWLY DRIVING IT SOUTHWARD. THE
MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A MODEST INTENSIFICATION
TO A PEAK 0F 40KTS BY TAU 48. AFTERWARD, LAND INTERFERENCE FROM
NORTHERN VIETNAM TO THE WEST AND HAINAN ISLAND TO THE EAST PLUS SST
COOLING DUE TO CYCLONIC UPWELLING DUE TO THE QS STORM MOTION WILL
GRADUALLY WEAKEN THE SYSTEM DOWN TO 25KTS BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT UP
TO TAU 48 THEN DIVERGE SIGNIFICANTLY AFTERWARD AS THE MODELS
DIVERGE ALONG AND ACROSS TRACK DURING THE QS PHASE AND SLOW SOUTHWARD
DRIFT, LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK AND INTENSITY
FORECASTS UP TO TAU 72, THEN LOW CONFIDENCE AFTERWARD.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//
NNNN

[doomhaMwx]

16W SIXTEEN 231018 0600 17.9N 108.7E WPAC 35 1003

T2316(Sanba)
Issued at 2023/10/18 07:20 UTC

Analysis at 10/18 06 UTC
Grade TS
Scale -
Intensity -
Center position N17°50′ (17.8°)
E108°35′ (108.6°)
Direction and speed of movement NW 15 km/h (8 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 280 km (150 NM)

Upgrade supported by ASCAT.

[Sciencerocks]

 https://twitter.com/VortixWx/status/1714628453532668379

[Sciencerocks]

 https://twitter.com/CIRA_CSU/status/1714695053636235698

[Sciencerocks]

 https://twitter.com/VortixWx/status/1715067553817428118