WDPN32 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (HALONG) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.1N 137.3E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 267 NM WEST-NORTHWEST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CLEAR EYE
FEATURE WITH SYMMETRIC CONVECTION AROUND THE LOW-LEVEL CIRCULATION
CENTER (LLCC). A SLIGHT CLOUD TOPS WARMING TREND AROUND THE CENTER 
SUGGESTS THAT INTENSIFICATION HAS SLOWED FOR NOW. RADIAL OUTFLOW 
REMAINS CONSISTENT. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON SATELLITE IMAGERY OF THE EYE FEATURE. THE INITIAL
INTENSITY OF 115 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
AGENCY AND OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   CIMSS ADT: 117 KTS AT 071300Z
   CIMSS AIDT: 111 KTS AT 071300Z
   CIMSS D-PRINT: 112 KTS AT 071300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 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: TYPHOON (TY) 28W (HALONG) WILL TRACK
NORTHWESTWARD AS IT ROUNDS THE AXIS OF THE SUBTROPICAL RIDGE TO THE
EAST. AFTERWARDS, TY 28W WILL RECURVE TO THE NORTH-NORTHEAST
THROUGH. TY 28W IS FORECAST TO REMAIN IN A HIGHLY FAVORABLE
ENVIRONMENT AT LEAST UNTIL TAU 24 WITH WARM (29-30 C) SEA SURFACE
TEMPERATURES (SST), LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), AND
GOOD OUTFLOW. FOLLOWING TAU 24 THE SYSTEM IS FORECAST TO ENCOUNTER
COOLER WATERS, HIGHER WIND SHEAR, AND RELATIVELY DRY AIR ENTRAINING 
THE CORE OF THE VORTEX - CONDITIONS THAT WILL CAUSE A WEAKENING TREND 
AND SIGNAL THE BEGINNING OF A SIMULTANEOUS TRANSITION INTO AN 
EXTRATROPICAL SYSTEM. AS TY HALONG CONTINUES TO TRANSIT NORTHEAST, 
UNFAVORABLE CONDITIONS WILL CAUSE A MORE DRAMATIC DECLINE OF THE 
SYSTEM. MAXIMUM WIND SPEEDS ARE EXPECTED TO WEAKEN TO 50 KTS
BY TAU 96 AS THE SYSTEM WILL HAVE COMPLETED ITS EXTRATROPICAL
TRANSITION. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD 
AGREEMENT ON THE FORECASTED CURVE WITH A CROSS-TRACK SPREAD UNDER 50 
NM UNTIL JUST BEFORE TAU 60. INTENSITY GUIDANCE HAS BECOME MORE 
ALIGNED WITH A PEAK INTENSITY OF 125 KTS WITH ONLY A FEW MODELS 
(HAFS, RIDE) CLINGING TO THE PROSPECT OF ANY STRONGER DEVELOPMENT. 
THE JTWC FORECAST REFLECTS A PEAK INTENSITY OF 125 KTS, REMAINING 
MINDFUL OF THE POSSIBILITY FOR MORE INTENSIFICATION BEFORE TAU 36. 
PREVIOUS MODEL GUIDANCE SHOWED A GRADUAL DECLINE OF THE SYSTEM 
ALTHOUGH EXPECTATION IS FOR TY 28W TO EXPERIENCE RAPID DECAYING 
DURING THE EXTRATROPICAL TRANSITION. FORECASTED ENVIRONMENTAL 
CONDITIONS, TRACK PROXIMITY TO THE JET, AND TROPICAL SPECIFIC MODEL 
ANALYSIS IS REFLECTED IN THE JTWC FORECAST.

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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