WDPN32 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (HALONG) WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.7N 140.9E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 579 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 28W
(HALONG) WITH A DEVELOPING EYE AND DEFINED CIRRUS FILAMENTS
EXTENDING POLEWARD. THE SYSTEM APPEARS TO BE BEGINNING TO RAPIDLY 
INTENSIFY AS THE EYE FEATURE HAS QUICKLY DEVELOPED OVER THE PAST 4 
HOURS OR SO. A 060608Z GMI 89 GHZ MICROWAVE IMAGE SHOWS A COMPACT 
CORE OF COLD CLOUD TOPS AND THE 37 GHZ VERSION OF THE SAME IMAGE 
SHOWS A SYMMETRIC MICROWAVE EYE IN THE LOWER LEVELS. ENVIRONMENTAL 
ANALYSIS INDICATES THAT 28W IS 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 TIMELY 
GMI MICROWAVE IMAGE. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH 
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS 
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE FROM A 052358Z METOP-C ASCAT
IMAGE

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 67 KTS AT 060340Z
   CIMSS ADT: 47 KTS AT 060600Z
   CIMSS AIDT: 60 KTS AT 060600Z
   CIMSS D-MINT: 52 KTS AT 060612Z

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: MEDIUM

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 36. NEAR TAU 36, THE SYSTEM IS EXPECTED TO TURN NORTHWARD IT
ROUNDS THE RIDGE AXIS. AFTER TAU 48, 28W IS FORECAST TO TRACK OFF
TO THE NORTHEAST WITH INCREASING TRACK SPEEDS AS THE SYSTEM BEGINS
TO INTERACT WITH THE STRONG MIDLATITUDE WESTERLIES. THE TRACK HAS
SHIFTED SLIGHTLY FURTHER SOUTH AT THE TIMING OF CPA TO YOKOSUKA
COMPARED TO THE PERVIOUS FORECAST. 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). AFTER TAU 48,
WESTERLY SHEAR WILL INCREASE, CAUSING 28W TO WEAKEN AS IT QUICKLY
TRACKS OFF TO THE 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 GUIDANCE IS IN FAIR AGREEMENT
WITH A CROSS-TRACK SPREAD OF 150 NM AT TAU 48 AND 215 NM AT TAU 72.
ALONG-TRACK SPREAD IS RATHER SIGNIFICANT THOUGH, MOSTLY ATTRIBUTED
TO THE ECMWF ENSEMBLE MEAN BEING MUCH SLOWER THAN THE REMAINDER OF
GUIDANCE. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH OVERALL MEDIUM CONFIDENCE. INTENSITY
GUIDANCE AGREES ON RAPID INTENSIFICATION THROUGH TAU 48 WITH MANY
RI AIDS TRIGGERING. MESOSCALE MODEL PEAK INTENSITIES RANGE FROM 130
KTS (HAFS-A) TO 140 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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