WPAC: 03W - Tropical Depression

[Hayabusa]

99W INVEST 240712 1800 12.8N 113.7E WPAC 15 0

[Hayabusa]

ABPW10 PGTW 130230
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/130230Z-130600ZJUL2024//
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 13.1N
113.8E, APPROXIMATELY 368 NM EAST-SOUTHEAST OF DA NANG, VIETNAM.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 122310Z SSMIS F-17 91GHZ
MICROWAVE IMAGE DEPICTS A BROAD AREA OF TURNING WITH A WEAKLY-DEFINED
LLCC. UPPER-LEVEL ANALYSIS INDICATES 99W IS IN A MARGINAL ENVIRONMENT
FOR DEVELOPMENT WITH HIGH (30-40 KNOT) VWS, OFFSET BY GOOD DIVERGENCE
ALOFT, AND WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN
GOOD AGREEMENT THAT 99W WILL CONTINUE TO DEVELOP OVER THE NEXT 24 HOURS
AND EVENTUALLY TRACK NORTHEAST ALONG THE COAST OF VIETNAM. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO 18 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
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.
3. JUSTIFICATION FOR REISSUE: ADDED LOW AREA IN PARA. 1.B.(1)//
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[Hayabusa]

WWJP27 RJTD 130600
WARNING AND SUMMARY 130600.
WARNING VALID 140600.
WARNING IS UPDATED EVERY 6 HOURS.
TROPICAL DEPRESSION 1000 HPA AT 13N 113E NNW SLOWLY.

ABPW10 PGTW 130600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/130600Z-140600ZJUL2024//
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
13.1N 113.8E IS NOW LOCATED NEAR 14.0N 112.7E, APPROXIMATELY 287 NM
EAST-SOUTHEAST OF DA NANG, VIETNAM. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A STRONG MID-LEVEL CIRCULATION CENTER NEAR 13.0N 113.3E,
WITH EXTENSIVE DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE
ASSOCIATED WITH A SOUTHWESTERLY WIND SURGE EVENT. A 122320Z SSMIS 37 GHZ
MICROWAVE IMAGE SHOWS DISORGANIZED CLUSTERS OF DEEP CONVECTION WITH NO
DISCERNABLE LOW-LEVEL CIRCULATION CENTER. HOWEVER, A 130152Z ASCAT-C
IMAGE REVEALS AN ELONGATED, WEAK CIRCULATION EMBEDDED WITHIN THE MONSOON
TROUGH, WITH A SWATH OF 20 TO 25 KNOT SOUTHWESTERLY WINDS DISPLACED WELL
TO THE SOUTH (GREATER THAN 180 NM). UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY FAVORABLE ENVIRONMENT WITH STRONG EQUATORWARD OUTFLOW OFFSET
BY MODERATE TO HIGH (20-25 KNOTS) VERTICAL WIND SHEAR. SEA SURFACE
TEMPERATURES OF 29-30 C ARE CONDUCIVE. GLOBAL MODELS INDICATE A WEST-
NORTHWESTWARD TO NORTHWESTWARD TRACK TOWARD VIETNAM OVER THE NEXT TWO
DAYS WITH SLOW DEVELOPMENT INTO A TROPICAL DEPRESSION. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1003 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.//
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[Hayabusa]

WDPN31 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 03W (THREE) WARNING
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 15.4N 110.4E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 127 NM EAST-SOUTHEAST OF DA NANG, VIETNAM
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
ILL-DEFINED FULLY-EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC). THE
MAJORITY OF ASSOCIATED CONVECTION REMAINS DISORGANIZED AND ISOLATED
THROUGHOUT THE WESTERN PERIPHERY OF THE LOW-LEVEL CIRCULATION ALONG
THE COASTLINE OF VIETNAM. A 141419Z ASCAT-C IMAGE REVEALED A BROAD
CIRCULATION WITH A SMALL SWATH OF 25 KNOT WINDS BETWEEN 65-70NM TO
THE NORTHEAST OF THE ASSESSED CIRCULATION CENTER, HOWEVER, THE
CENTER IS FLANKED BY LARGE AREAS OF 20 KNOT SWATHS THROUGHOUT THE
WESTERN AND NORTHEASTERN QUADRANTS. COASTAL AND SHIP SURFACE
OBSERVATIONS INDICATED AVERAGE WINDS BETWEEN 13-18 KNOTS, WITH A
MINIMUM SLP VALUE RANGING BETWEEN 1000 MB TO 1002 MB. THE OVERALL
ENVIRONMENT IS ASSESSED AS UNFAVORABLE DUE TO 25-30 KNOT VERTICAL
WIND SHEAR (VWS) AND IMPENDING FRICTIONAL EFFECTS DUE TO
INTERACTION WITH COASTAL VIETNAM OVER THE NEXT 12 TO 24 HOURS. THE
CURRENT AND ONLY AGENCY DVORAK INTENSITY ESTIMATE FROM RJTD IS
T0.5.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: NO CURRENT ESTIMATE

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 25-30 KTS
SST: 28-30 CELSIUS
OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: HIGH
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) 03W IS FORECAST TO
TRACK WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN EDGE OF THE WELL-
ESTABLISHED SUBTROPICAL RIDGE THROUGH TAU 12 AND DISSIPATE OVER
VIETNAM AND LAOS BETWEEN TAU 24 AND TAU 36, RESPECTIVELY. AS TD 03W
CONTINUES WESTWARD, THE SYSTEM IS ANTICIPATED TO REMAIN 25 KNOTS
THROUGH A HARSH ENVIRONMENT OF STRONG VWS BETWEEN 25-30 KNOTS. BETWEEN
TAU 12 AND TAU 24, TD 03W IS EXPECTED TO MAKE LANDFALL AND BEGIN ITS
DISSIPATION PHASE DUE TO INCREASED FRICTIONAL INFLUENCES AND
SUSTAINED DESTRUCTIVE VWS AS SUPPORTIVE UPPER-LEVEL OUTFLOW REMAINS
MINIMAL FOR ANY FURTHER INTENSIFICATION. BY TAU 36, TD 03W IS
FORECASTED TO COMPLETE DISSIPATION OVER LAND.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN VERY STRONG
AGREEMENT THROUGH TAU 36 WITH A 55 NM CROSS-TRACK SPREAD AT THE END
OF THE FORECAST PERIOD. THE DETERMINISTIC MODEL TRACKERS CONTINUE
TO ALIGN WITH AN EXPECTED WEST-NORTHWEST MOVEMENT INTO LANDFALL
WITH VERY HIGH CONFIDENCE. THE COAMPS-TC INTENSITY PROBABILITY
PRODUCT INDICATES A LOW PROBABILITY (10-20 PERCENT) OF STEADY TO
MODERATE INTENSIFICATION BEFORE LANDFALL. THE GEFS AND EPS
ENSEMBLES ILLUSTRATE CONTINUED TROPICAL DEPRESSION STRENGTH
INTENSITIES AS WELL (25-34 KNOTS) BEFORE SUSTAINED STRONG VWS
(25-30 KNOTS) AND INCREASED LAND INTERACTION BEGINS TO DISSIPATE TD
03W.

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