WDPN31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (YINXING) WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.2N 127.5E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 388 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS
CONTINUED TO SLOWLY INTENSIFY IN THE PHILIPPINE SEA AS EVIDENCED BY
FEEDER BANDS WRAPPING TIGHTER INTO A SYMMETRICAL AND MORE COMPACT
CENTRAL DENSE OVERCAST WITH DEEPENING AND OVERSHOOTING CLOUD TOPS
AND A PINHOLE FORMATIVE EYE. ADDITIONALLY, THE MSI LOOP SHOWS A
VIGOROUS POLEWARD AND A MODEST EQUATORWARD OUTFLOW. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE FORMATIVE EYE,
LINED UP WITH A MICROWAVE EYE IN THE 042136Z WSFM 89GHZ IMAGE. THE
INITIAL INTENSITY IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON THE
HIGHER END OF AGENCY AND AUTOMATED DVORAK ESTIMATES (SEE BELOW).
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW VWS, WARM
ALONG-TRACK SSTS, AND ROBUST VENTILATION FROM THE DUAL OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 79 KTS AT 042330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 05-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: TYPHOON YINXING WILL CONTINUE ON ITS CURRENT
NORTHWESTWARD TRACK UP TO TAU 36; AFTERWARD, A SECONDARY STR BUILDING 
IN FROM THE WEST NEAR HAINAN WILL SLOW DOWN THE SYSTEM THEN ASSUME 
STEERING, DRIVING THE CYCLONE ON A MORE WESTWARD TRAJECTORY THROUGH 
THE LUZON STRAIT AND INTO THE SOUTH CHINA SEA (SCS). THE FAVORABLE 
ENVIRONMENT WILL PROMOTE A GRADUAL INTENSIFICATION TO A PEAK OF 100KTS 
BY TAU 36, FUELED BY A JOLT OF INCREASED POLEWARD OUTFLOW AS THE 
SYSTEM APPROACHES THE SOUTHWESTERLY JETS AHEAD OF A TRANSITING MID-
LATITUDE TROUGH. AFTER TAU 36, THE RELATIVE VWS WILL INCREASE, SST AND 
OHC VALUES DECREASE IN THE WAKE OF A PREVIOUS CYCLONE (23W), 
INTERACTION WITH LUZON, THEN THE DRIFT INTO A COLD NORTHEASTERLY SURGE 
IN THE SCS WILL SLOWLY ERODE THE SYSTEM DOWN TO 70KTS BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT WITH
AN EVEN ACROSS SPREAD OF A MERE 100NM BY TAU 72; AFTERWARD, THE
MODELS SIGNIFICANTLY SPREAD OUT WITH NVGM THE NOTABLE AND ERRATIC
RIGHT-OF-TRACK OUTLIER, LENDING HIGH CONFIDENCE UP TO TAU 72, THEN
LOW CONFIDENCE AFTERWARD, TO THE JTWC TRACK FORECAST. THERE IS
MEDIUM CONFIDENCE TO THE INTENSITY FORECAST UP TO TAU 72, THEN LOW
CONFIDENCE AFTERWARD. 


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