WDPN32 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 19W (CHANTHU) WARNING NR 
016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.1N 124.1E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 116 NM SOUTHEAST OF APARRI, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A COMPACT SYSTEM
THAT HAS REGAINED ITS SYMMETRICAL AND DENSE STRUCTURE AS ITS
CENTRAL CONVECTION DEEPENED AND ITS EYE HAS SHRUNK BACK TO A
SHARPLY-OUTLINED 5-NM PINHOLE DIAMETER. ENHANCED INFRARED SATELLITE
ANIMATION AND A CIMSS MICROWAVE-BASED M-PERC PRODUCT INDICATE THE
CYCLONE HAS UNDERGONE A SECONDARY EYEWALL REPLACEMENT CYCLE. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE ON THE PINHOLE EYE
THAT STACKED VERTICALLY DOWN TO THE LOW LEVEL CIRCULATION CENTER.
THE INITIAL INTENSITY IS ASSIGNED WITH HIGH CONFIDENCE BASED ON
CONGRUENT AND CONCENTRIC DVORAK ESTIMATE FIXES FROM PGTW, KNES,
RJTD, AND RCTP. THE ENVIRONMENT REMAINS HIGHLY FAVORABLE WITH LOW
VWS AND STRONG RADIAL OUTFLOW ALOFT, AND VERY WARM ALONG-TRACK SSTS
IN THE PHILIPPINE SEA. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF THE DEEP-LAYERED STR TO THE NORTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.5 - 127 KTS
   KNES: T6.5 - 127 KTS
   CIMSS ADT: 107 KTS AT 092340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: FOLLOWING ERC, STY CHANTU IS POISED FOR
ANOTHER INTENSIFICATION, ALBEIT A MORE MODEST ONE AS IT ROUNDS THE
WESTERN EDGE OF THE STR UNDER A HIGHLY FAVORABLE ENVIRONMENT TOWARD
TAIWAN, PEAKING AT 135KTS IN THE LUZON STRAIT JUST BEFORE LANDFALL
INTO SOUTHERN TAIWAN AROUND TAU 48. AFTERWARD, LAND INTERACTION
WITH TAIWAN AND INCREASING VWS WILL GRADUALLY ERODE THE SYSTEM AS
IT EXITS INTO THE EAST CHINA SEA AND BEELINES TOWARD CHEJU ISLAND,
DOWN TO 50KTS BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH NVGM
THE NOTABLE LEFT OUTLIER, EVENLY SPREADING TO 232NM BY TAU 120. IN
VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST
UP TO TAU 72, AND MEDIUM CONFIDENCE AFTERWARD. THE FORECAST TRACK
IS LAID SLIGHTLY RIGHT OF THE MODEL CONSENSUS TO OFFSET NVGM. THERE
IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST DUE TO THE
VARIABILITY THAT OFTEN COMES WITH LAND PASSAGE.  

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