WDPN32 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (HALONG) WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.2N 140.0E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 546 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
28W WITH FRAGMENTATION IN THE WESTERN SEMICIRCLE OF THE DEVELOPING
EYEWALL. CLOUD TOPS IN THE SOUTHERN PERIPHERY HAVE COOLED OVER THE
PAST 6 HOURS WITH THE COLDEST TOPS NOW MEASURING AROUND -88 C.
ENVIRONMENTAL ANALYSIS INDICATES THAT 28W CONTINUES TO BE IN A
HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD
OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (29-30
C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE EYE FEATURE IN ANIMATED EIR IMAGERY.
THE INITIAL INTENSITY OF 70 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE HIGHER END OF THE AGENCY DVORAK AND CIMSS OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE POSITIONED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 49 KTS AT 061200Z
   CIMSS AIDT: 60 KTS AT 061200Z
   CIMSS D-PRINT: 69 KTS AT 061200Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 28W IS FORECAST TO TRACK NORTHWESTWARD, ALONG
THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE EAST THROUGH
TAU 24. NEAR TAU 24, THE SYSTEM IS EXPECTED TO TURN NORTHWARD AS IT
ROUNDS THE SUBTROPICAL RIDGE AXIS. AFTER TAU 48, 28W IS FORECAST TO
TRACK OFF TO THE EAST-NORTHEAST WITH INCREASING TRACK SPEEDS AS THE
SYSTEM BEGINS TO INTERACT WITH THE STRONG MIDLATITUDE WESTERLIES.
REGARDING INTENSITY, 28W IS FORECAST TO RAPIDLY INTENSIFY OVER THE
NEXT 48 HOURS TO A PEAK OF AROUND 130 KTS. THE ENVIRONMENT IS
EXPECTED TO REMAIN HIGHLY FAVORABLE, PRIME FOR RAPID INTENSIFICATION 
(RI). WESTERLY SHEAR WILL SIGNIFICANTLY INCREASE TO AROUND 35-40 KTS 
AT TAU 72, CAUSING 28W TO RAPIDLY WEAKEN AS IT TRACKS OFF TO THE 
EAST-NORTHEAST. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN AROUND 
TAU 72 AND COMPLETE NEAR TAU 96 AS THE SYSTEM BECOMES EMBEDDED WITHIN 
THE MIDLATITUDE WESTERLIES. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS NOW IN GOOD
AGREEMENT WITH AROUND A 90 NM CROSS-TRACK SPREAD AT BOTH TAU 48 AND
TAU 72. ALONG-TRACK SPREAD IS 205 NM AT TAU 72 WITH ECMWF BEING THE
SLOWEST AND GALWEM BEING THE FASTEST THROUGH THE RECURVE. THE JTWC
TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH
OVERALL MEDIUM CONFIDENCE. INTENSITY GUIDANCE AGREES ON RAPID
INTENSIFICATION (RI) THROUGH TAU 48 WITH MANY RI AIDS CONTINUING TO
TRIGGER. MESOSCALE MODEL PEAK INTENSITIES RANGE FROM 130 KTS
(HAFS-A) TO 150 KTS (COAMPS-TC) AT TAU 48. ALL MODELS ALSO
AGREE ON WEAKENING AFTER TAU 60. THE JTWC INTENSITY FORECAST IS
PLACED IN-LINE WITH HAFS-A THROUGHOUT THE FORECAST PERIOD WITH
MEDIUM CONFIDENCE DUE TO INHERENT UNCERTAINTIES REGARDING THE RI
RATE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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