WDPN34 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (USAGI) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.8N 120.5E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 168 NM SOUTH OF KAOHSIUNG, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS EXITED INTO THE LUZON STRAIT AND RE-CONSOLIDATED AFTER BEING
SIGNIFICANTLY SPLINTERED AND ERODED BY RUGGED TERRAIN DURING ITS
PASSAGE THROUGH NORTHEASTERN LUZON. THE COLD CENTRAL COVER HAS
REFORMED AND DEEPENED WHILE TRAILING A FEW FRAGMENTED RAIN BANDS.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A DEFINED
LOW LEVEL CIRCULATION CENTER IN A COMPOSITE RADAR LOOP FROM THE
TAIWAN CENTRAL WEATHER BUREAU. THE INITIAL INTENSITY OF 65KTS IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE OVERALL ASSESSMENT OF
AGENCIES. FINAL-T OF 4.0 AND AUTOMATED DVORAK ESTIMATES AND REFLECTS 
THE 6-HR CONSOLIDATION AND EIR CONVECTIVE STRUCTURE. ANALYSIS 
INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH COOL (26-27C) SST, 
MODERATE TO STRONG, AND MODERATE EQUATORWARD OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T5.0 - 90 KTS
   CIMSS ADT: 65 KTS AT 141730Z
   CIMSS DPRNT: 56 KTS AT 141800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY USAGI WILL CONTINUE TO TRACK GENERALLY
NORTHWARD AS IT ROUNDS THE WESTERN RIM OF THE STEERING STR, FORECASTED 
MAKE LANDFALL NEAR KAOHSIUNG AROUND TAU 30. AFTERWARD, A SECONDARY STR
BUILDING IN FROM THE WEST NEAR HAINAN WILL COMPETE FOR STEERING AND
SLOW DOWN THE STORM MOTION, RENDERING THE CYCLONE IN A
QUASI-STATIONARY MODE IN THE COL AREA BETWEEN THE TWO STRS. AFTER
TAU 48, THE SECONDARY STR WILL ASSUME STEERING AND DRIVE THE
CYCLONE SOUTHWESTWARD INTO THE TAIWAN STRAIT. COOL SSTS, INCREASING
VWS, AND LAND INTERACTION WITH THE RUGGED TERRAIN OF TAIWAN WILL
SLOWLY ERODE THE SYSTEM TO DISSIPATION BY TAU 72 AS IT GETS
ABSORBED INTO THE COLD NORTHEASTERLY SURGE IN THE TAIWAN STRAIT.
THERE IS A DISTINCT POSSIBILITY THAT THE SYSTEM WILL DISSIPATE OVER
TAIWAN.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT UP
TO TAU 36; AFTERWARD, A FEW MODELS TRACK THE VORTEX NORTHEASTWARD
LENDING OVERALL MEDIUM CONFIDENCE TO THE JTWC TRACK AND INTENSITY
FORECASTS THAT ARE LAID CLOSE TO THE MODEL CONSENSUS. 

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