WDPN31 PGTW 060300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 12W (YAGI) WARNING NR 
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.2N 112.2E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 371 NM EAST-SOUTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 49 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
WELL-ORGANIZED SUPER TYPHOON 12W (YAGI) EXHIBITING SYMMETRICAL,
RADIAL OUTFLOW, FROM A CLEARLY VISIBLE, ROUND EYE FEATURE, LENDING
TO A HIGH CONFIDENCE TO INITIAL POSITION ASSESSMENT. AS THE SYSTEM
IS NOW PAST THE AXIS OF THE DEEP SUBTROPICAL RIDGE TO THE
NORTHEAST, IT IS FINALLY STARTING TO TURN WEST-NORTHWESTWARD. STRONG
OUTFLOW, AS WELL AS CONTINUOUSLY WARM SEA SURFACE TEMPERATURES, LOW
VERTICAL WIND SHEAR AND HIGH OCEAN HEAT CONTENT ARE STILL FAVORING
DEVELOPMENT, OFFSET BY THE BEGINNING OF LAND INTERACTION BETWEEN
STY YAGI AND HAINAN ISLAND. THE INITIAL INTENSITY OF 130 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE MAJORITY OF AGENCY AND
OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH-EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T7.0 - 140 KTS 
   RCTP: T7.5 - 155 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 145 KTS AT 052130Z
   CIMSS ADT: 132 KTS AT 060000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG RADIAL

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: STY YAGI WILL APPROACH THE ISLAND OF HAINAN ON A 
WEST-NORTHWESTWARD TRACK AND IS ABOUT TO CROSS THE NORTHERN PART OF 
THE ISLAND AND INTO THE GULF OF TONKIN. STY 12W IS FORECAST TO START 
WEAKENING DUE TO LAND INTERACTION AS IT PASSES OVER HAINAN. THE 
WEAKENING PROCESS WILL CONTINUE AS THE SYSTEM TRACKS THROUGH THE GULF 
OF TONKIN, OFFSET SLIGHTLY BY HIGH OCEAN HEAT CONTENT, HIGH SEA 
SURFACE TEMPERATURES, LOW VERTICAL WIND SHEAR, AND CONTINUOUSLY 
SUPPORTIVE UPPER LEVEL DIVERGENCE. GIVEN THE SIZE OF THE SYSTEM AND 
THE IMPACT OF LAND INTERACTION ON THE OUTER BANDS, THE INTENSITY 
GUIDANCE CONSENSUS IS PROJECTING A STEADY WEAKENING OF THE SYSTEM. BY 
THE TIME STY YAGI MAKES LANDFALL OVER NORTHERN VIETNAM AROUND TAU 36 
IT IS FORECAST TO WEAKEN TO 80 KTS, FOLLOWED BY BEGINNING OF 
DISSIPATION, DUE TO INTERACTION WITH RUGGED TERRAIN AND THE ANNAMITE 
MOUNTAIN RANGE. SYSTEM IS CURRENTLY FORECAST TO COMPLETE DISSIPATION 
BY TAU 72.

MODEL DISCUSSION: MODEL GUIDANCE IS IN GOOD AGREEMENT BOTH IN
REGARDS TO TRACK AND INTENSITY. THE CROSS-TRACK SPREAD OVER HAINAN
IS AT 30 NM AND 100 NM AT LANDFALL OVER NORTHERN VIETNAM BY TAU 36.
INTENSITY GUIDANCE IS CONSISTENT ACROSS ALL MEMBERS OF THE MULTI-MODEL 
CONSENSUS, WITH JTWC FORECAST PLACED ON THE HIGHER SIDE OF THE 
CONSENSUS, TO ACCOUNT FOR THE IMPACT OF FAVORABLE CONDITIONS WHILE THE 
STY YAGI TRANSITS OVER WATER, WHICH SLIGHTLY OFFSETS THE IMPACTS OF 
LAND INTERACTION.

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