WDPN31 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (TALIM) WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.8N 112.2E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 143 NM SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 04W HAS LIKELY REACHED PEAK INTENSITY OVER THE
PAST SIX HOURS AS THE OUTERMOST EXTENT OF THE SYSTEM APPROACHED
LAND AND BEGAN EXPERIENCING FRICTION-INDUCED CYCLOLYSIS. ANIMATED 
PROXYVIS SATELLITE IMAGERY DEPICTS A MATURE AREA OF DEEP CONVECTION 
WITH WELL-DEVELOPED SPIRAL BANDING WRAPPING INTO A RAGGED-EYE OF 32NM
DIAMETER. A 170613Z ATMS 165GHZ MICROWAVE IMAGE SHOWS THE DEEPEST 
CONVECTIVE ELEMENTS 80NM EQUATORWARD OF THE SOUTHERN-MOST EYEWALL 
WRAPPING CYCLONICALLY INTO THE EYE, WITH THE LIGHTEST CONVECTION 
PRESENT IN THE NORTHWEST QUADRANT. EXTENSIVE SHALLOW BANDING PERSISTS 
OVER THE NORTHERN SEMICIRCLE PRIMARILY DUE TO DRY AIR ENTRAINMENT. THE 
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE 
AFOREMENTIONED ATMS MICROWAVE IMAGE AND A 170600Z ENHANCED INFRARED
SATELLITE IMAGE. A MARGINALLY FAVORABLE ENVIRONMENT IS EVIDENCED BY 
CONTINUED OUTFLOW SUPPORT AND WARM SST OFFSET BY DRY AIR ENTRAINMENT 
AND FRICTIONAL EFFECTS. THE INITIAL INTENSITY OF 70 KTS IS ASSESSED 
WITH MEDIUM CONFIDENCE WITHIN THE RANGE OF PGTW, RCTP, AND KNES DVORAK 
ESTIMATES AND REFINED USING A 162219Z SYNTHETIC APERTURE RADAR IMAGE. 

INITIAL WIND RADII BASIS: SAR DATA, ASCAT DATA AND SURFACE
OBSERVATIONS 

CURRENT STEERING MECHANISM: DEEP LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 87 KTS AT 170612Z
   CIMSS ADT: 94 KTS AT 170540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TS 04W IS FORECAST TO TRACK WEST-NORTHWESTWARD
THROUGH TAU 48 UNDER THE STEERING INFLUENCE OF DEEP-LAYER EASTERLY
FLOW TO THE NORTH. LAND INTERACTION AND DRY AIR ENTRAINMENT ALONG
THE NORTHERN PERIPHERY WILL GRADUALLY CAUSE 04W TO DISSIPATE
BY TAU 48.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 
CROSS TRACK SPREAD OF 85NM AT TAU 48. RELIABLE INTENSITY GUIDANCE 
SUPPORTS THE RAPID WEAKENING PHASE.

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