WDPN32 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05W (GAEMI) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.6N 125.1E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 335 NM SOUTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
VERTICAL WIND SHEAR (VWS) HAS DECREASED SIGNIFICANTLY OVER THE PAST
12 HOURS, WITH A MORE VERTICALLY ALIGNED VORTEX AND IMPROVED RADIAL
OUTFLOW. CONSEQUENTLY, ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS AN IMPROVED, MORE SYMMETRIC CENTRAL DENSE OVERCAST WITH AN
INCIPIENT EYE FEATURE EVIDENT AFTER 230700Z. A 230429Z AMSR2 36 GHZ
MICROWAVE IMAGE REVEALS A COMPACT CORE SURROUNDING A WELL-DEFINED
MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH
HIGH CONFIDENCE. A 230143Z ASCAT-C BULLSEYE IMAGE WAS USED TO
ADJUST THE 34-KNOT WIND RADII ANALYSIS AND REFLECTS EXPANSIVE
GALE-FORCE WINDS OVER THE EASTERN SEMICIRCLE. UPPER-LEVEL ANALYSIS
INDICATES A HIGHLY FAVORABLE ENVIRONMENT WITH ROBUST EASTWARD
OUTFLOW, ENHANCED BY THE TUTT POSITIONED TO THE EAST, AND VERY
STRONG, BROAD EQUATORWARD OUTFLOW. ADDITIONALLY, SST AND OCEAN HEAT
CONTENT VALUES REMAIN VERY HIGH AND SUPPORTIVE FOR RAPID
INTENSIFICATION. THE INITIAL INTENSITY OF 90 KTS IS ASSESSED WITH
HIGH CONFIDENCE BASED ON CONCURRENT SUBJECTIVE DVORAK ESTIMATES OF
90 KNOTS FROM ALL AGENCIES. CIMSS ADT, AIDT AND DMINT OBJECTIVE 
INTENSITY ESTIMATES REMAIN SLIGHTLY LOWER AND RANGE FROM 83-85 KNOTS.  

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE EAST, WITH A WESTWARD EXTENSION OF THE STR
POSITIONED TO THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 71 KTS AT 230700Z
   CIMSS ADT: 84 KTS AT 230600Z
   CIMSS AIDT: 83 KTS AT 230600Z
   CIMSS DMINT: 85 KTS AT 230519Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: INTRODUCED A RAPID INTENSIFICATION
PHASE AND INCREASED THE PEAK INTENSITY TO 120 KNOTS.

FORECAST DISCUSSION: TYPHOON (TY) 05W IS FORECAST TO GRADUALLY TURN 
NORTHWESTWARD TO WEST-NORTHWESTWARD OVER THE NEXT 36 HOURS AS THE 
STEERING INFLUENCE TRANSITIONS TO THE STR EXTENSION TO THE NORTH. DUE 
TO THE HIGHLY FAVORABLE ENVIRONMENTAL CONDITIONS AND DEVELOPING EYE, 
RAPID INTENSIFICATION (RI) IS EXPECTED THROUGH TAU 24 WITH A PEAK 
INTENSITY OF 120 KNOTS AT TAU 24. AFTER TAU 24, VWS WILL INCREASE AS 
THE SYSTEM APPROACHES NORTHEAST TAIWAN, WITH LANDFALL ANTICIPATED 
NEAR TAU 36. RAPID WEAKENING WILL OCCUR AS THE SYSTEM TRACKS OVER 
TAIWAN AND ACROSS THE TAIWAN STRAIT. AFTER TY 05W MAKES LANDFALL OVER 
SOUTHEAST CHINA JUST AFTER TAU 48, RAPID WEAKENING WILL CONTINUE WITH 
DISSIPATION EXPECTED BY TAU 96 AS THE SYSTEM TRACKS NORTHWESTWARD.    

MODEL DISCUSSION: MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH 
TAU 36 WITH A 50 NM CROSS-TRACK SPREAD AT TAU 36. AFTER TAU 36, 
GUIDANCE DIVERGES WITH INCREASING UNCERTAINTY IN THE TRACK FORECAST. 
IN GENERAL, RELIABLE INTENSITY GUIDANCE SUPPORTS THE RI PHASE WITH 
NUMEROUS RI FORECAST AIDS TRIGGERED AND INTENSITY GUIDANCE PEAKING AS 
HIGH AS 130 KNOTS AT TAU 24. AFTER TAU 24, GUIDANCE SUPPORTS RAPID 
WEAKENING.   

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: HIGH//
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