Tropical Cyclone 01S (01S)

WTXS31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 01S (ONE) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 01S (ONE) WARNING NR 005    
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   181800Z --- NEAR 12.2S 82.5E
     MOVEMENT PAST SIX HOURS - 265 DEGREES AT 15 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
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 12.2S 82.5E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   190600Z --- 13.0S 80.5E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
182100Z POSITION NEAR 12.4S 82.0E.
18JUL25. TROPICAL CYCLONE 01S (ONE), LOCATED APPROXIMATELY 666 NM
EAST-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED WESTWARD AT 15 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS 01S NEARLY COMPLETELY VOID OF DEEP CONVECTION WITH
AN INCREASINGLY DISORGANIZED LOW-LEVEL CIRCULATION CENTER (LLCC).
AN 181609Z METOP-B ASCAT PASS REVEALED WEAK WINDS (5-10 KTS) WITHIN
THE NORTHERN SEMICIRCLE AND 25-30 KTS WITHIN THE SOUTHERN
SEMICIRCLE, WHICH SUPPORTED THE INITIAL INTENSITY ESTIMATE. THE
ENVIRONMENT IS EXPECTED TO WORSEN AS DRY AIR ENTRAINS INTO THE
VORTEX FROM THE NORTH AND NORTHERLY VERTICAL WIND SHEAR INCREASES.
NUMERICAL MODEL GUIDANCE IS IN AGREEMENT ON THE TRACK OF 01S AND
AGREES ON A GRADUAL WEAKENING TREND OVER THE NEXT 48 HOURS.
THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON
WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR
SIGNS OF REGENERATION. MINIMUM CENTRAL PRESSURE AT 181800Z IS
1003 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 181800Z IS 12 FEET.//
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WDXS31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01S (ONE) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.8S 85.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 814 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW-LEVEL CIRCULATION, WITH FLARING, ISOLATED DEEP
CONVECTION SHEARED OVER THE SOUTHERN QUADRANT. A 180335Z ASCAT-B
IMAGE REVEALS A WEAKENING CIRCULATION, OPENING UP OVER THE NORTHERN
QUADRANT, WITH A SMALL AREA OF 30 KNOT VECTORS CONFINED TO THE
SOUTHERN QUADRANT. THE INITIAL INTENSITY IS HELD SLIGHTLY HIGHER THAN 
THE ASCAT VECTORS BASED ON THE HISTORICALLY LOW BIAS. THE INITIAL 
INTENSITY ASSESSMENT IS SUPPORTED BY THE PGTW CURRENT INTENSITY 
ESTIMATE OF 2.5 (35 KNOTS) AND THE RECENT CIMSS SATCON ESTIMATE. 
ENVIRONMENTAL CONDITIONS REMAIN MARGINAL, WITH MODERATE (20 KNOTS) 
MID-LEVEL VERTICAL WIND SHEAR (VWS) AND SIGNIFICANT MID-LEVEL DRY AIR 
ENTRAINMENT.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   FMEE: T2.0 - 30 KTS
   CIMSS SATCON: 36 KTS AT 180345Z
   CIMSS ADT: 33 KTS AT 180615Z
   CIMSS AIDT: 30 KTS AT 180615Z
   CIMSS D-PRINT: 27 KTS AT 180545Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 01S IS EXPECTED TO TRACK
WEST-SOUTHWESTWARD THROUGH TAU 24 ALONG THE NORTHERN PERIPHERY OF
THE LOW-LEVEL STR. THE SYSTEM WILL CONTINUE TO WEAKEN DUE TO STEADY
MODERATE VWS AND INCREASING DRY AIR ENTRAINMENT. THE SYSTEM WILL
DISSIPATE BY TAU 24.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 24, WITH A 45-NM CROSS-TRACK SPREAD AT TAU 24. THE
ECENS AND GEFS ENSEMBLES SUPPORT THE JTWC TRACK AND INTENSITY
FORECAST WITH MEDIUM CONFIDENCE.  

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