Fifteen

WTPN34 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 15W (FIFTEEN) WARNING NR 001//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/090552ZAUG2026//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. TROPICAL DEPRESSION 15W (FIFTEEN) WARNING NR 001    
   04 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   100000Z --- NEAR 25.6N 160.1E
     MOVEMENT PAST SIX HOURS - 020 DEGREES AT 11 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
   REPEAT POSIT: 25.6N 160.1E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   101200Z --- 27.2N 160.4E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 355 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   110000Z --- 28.9N 160.2E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
100300Z POSITION NEAR 26.0N 160.2E.
10AUG26. TROPICAL DEPRESSION 15W (FIFTEEN), LOCATED APPROXIMATELY
522 NM NORTHWEST OF WAKE ISLAND, HAS TRACKED NORTH-NORTHEASTWARD
AT 11 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 100000Z IS 997 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 100000Z IS 12 FEET. NEXT WARNINGS AT
100900Z, 101500Z AND 102100Z.
REFER TO TYPHOON 12W (DOLPHIN) FINAL WARNING (WTPN31 PGTW).
REFER TO TROPICAL STORM 13W (PEILOU) WARNINGS (WTPN32 PGTW)
FOR SIX-HOURLY UPDATES.
REFER TO TROPICAL STORM 14W (CHAN-HOM) WARNINGS (WTPN33 PGTW)
FOR SIX-HOURLY UPDATES.
2. THIS CANCELS AND SUPERCEDES REF A (WTPN21 PGTW 090600).//
NNNN

WDPN34 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.6N 160.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 522 NM NORTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION 15W WITH A SMALL SYMMETRICAL CENTRAL DENSE OVERCAST
(CDO) FEATURE OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A
092248Z METOP-C ASCAT PASS REVEALED THAT THE WIND FIELD IS HIGHLY
ASYMMETRIC WITH A MARKED WEAKNESS IN THE WESTERN SEMICIRCLE. WINDS
ON THE EASTERN SIDE WERE MEASURED TO BE AROUND 25-30 KTS, LENDING
HIGH CONFIDENCE TO THE INITIAL INTENSITY ASSESSMENT. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI AND
EXTRAPOLATION FROM THE ASCAT PASS. ENVIRONMENTAL ANALYSIS INDICATES
THAT TD 15W IS IN A MARGINAL ENVIRONMENT CHARACTERIZED BY MODERATE
POLEWARD OUTFLOW ALOFT, LOW TO MODERATE (15-20 KTS) WESTERLY
VERTICAL WIND SHEAR, DRY AIR ENTRAINMENT, AND WARM (29-30 C) SEA
SURFACE TEMPERATURES.

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

CURRENT STEERING MECHANISM: LARGE-SCALE DEEP-LAYER CYCLONIC FLOW
CENTERED TO THE NORTHWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.0 - 25 KTS
   KNES: T1.5 - 25 KTS
   PHFO: T2.0 - 30 KTS
   CIMSS D-PRINT: 36 KTS AT 100000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE WEST

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: TD 15W IS FORECAST TO TRACK NORTHWARD WITHIN
THE LARGE-SCALE CYCLONIC FLOW THROUGH THE REST OF ITS SHORT LIFESPAN. 
AN INCOMING UPPER-LEVEL TROUGH IS EXPECTED TO PROPAGATE EASTWARD AND 
CRASH INTO 15W, INDUCING OVER 30 KTS OF WESTERLY SHEAR ON THE SYSTEM 
WITHIN THE NEXT 12 HOURS. THE HIGH SHEAR COMBINED WITH AN ASYMMETRIC 
WIND FIELD IS EXPECTED TO QUICKLY WEAKEN 15W. COMPLETE DISSIPATION AND 
UNRAVELING OF THE VORTEX IS FORECAST TO OCCUR AROUND TAU 24.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN RELATIVELY
POOR AGREEMENT CONSIDERING HOW SHORT THE FORECAST PERIOD IS.
CROSS-TRACK SPREAD AT TAU 24 IS OVER 100 NM, WHICH IS PRIMARILY DUE
TO THE ECMWF DETERMINISTIC TRACKER SHOWING AN IMMINENT NORTHWESTWARD 
TURN. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL 
CONSENSUS WITH MEDIUM CONFIDENCE. RELIABLE INTENSITY GUIDANCE AGREES 
ON WEAKENING THROUGH TAU 24 AND THE JTWC INTENSITY FORECAST FOLLOWS 
SUIT. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM//
NNNN

• NEXRAD radar — no radar coverage over the open West Pacific.
• Storm-surge inundation — no public storm-surge model for this basin.
• Wind-speed probabilities — JTWC does not publish them.
• Watches and warnings — issued by local agencies (PAGASA, JMA, CWA), not JTWC.
• Reconnaissance aircraft — no routine aircraft reconnaissance in the West Pacific.
• Rapid-intensification and shear diagnostics — SHIPS-based guidance is not published for this basin.