WDPN32 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (HALONG) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 29.7N 137.1E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 348 NM SOUTH-SOUTHWEST OF CAMP FUJI
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 28W
(HALONG) WITH AN OBSERVABLE AND EVIDENT EYE-FEATURE, SURROUNDED BY
SUPPORTIVE CONVECTION WRAPPED UNIFORMLY AROUND THE LOW-LEVEL
CIRCULATION CENTER (LLCC). OVER THE LAST FEW HOURS, THE EYE HAS
BECOME INCREASINGLY CLOUD-FILLED WHILE CONVECTION IMMEDIATELY
OUTSIDE OF THE EYEWALL HAS WARMED TO -73 C. ALOFT, STRONG RADIAL
OUTFLOW HAS PERSISTED, MARKED BY BURSTING AND STRIATED CIRRUS LINES
AWAY FROM THE CENTER. ENVIRONMENTAL CONDITIONS HAVE REMAINED
FAVORABLE WITH WARM SEA SURFACE TEMPERATURES (28-29 C), LOW
VERTICAL WIND SHEAR (VWS) BETWEEN 5-10 KTS, AND ROBUST UPPER-LEVEL
OUTFLOW. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE OBSERVABLE EYE-FEATURE ON ANIMATED MSI. THE INITIAL
INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON ALL SUBJECTIVE
AGENCY DVORAK ESTIMATES ALIGNED AT T6.0 AND CIMSS OBJECTIVE
INTENSITY VALUES RANGING FROM 119-125 KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE POSITIONED
DIRECTLY TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   CIMSS ADT: 119 KTS AT 080100Z
   CIMSS AIDT: 121 KTS AT 080100Z
   CIMSS D-PRINT: 125 KTS AT 080100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: 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: TY 28W IS FORECASTED TO COMPLETE TRACKING
AROUND THE WESTERN-MOST EXTENT OF THE DEEP-LAYER SUBTROPICAL RIDGE
DIRECTLY TO THE EAST OVER THE NEXT 24 HOURS. FOLLOWING TAU 24 AND
INTO TAU 36, TY 28W WILL BEGIN INTERACTING WITH THE SOUTHERN EXTENT
OF THE MID-LATITUDE WESTERLIES TO THE NORTH AND CONTINUE TRACKING
EAST-NORTHEAST UNTIL THE END OF THE FORECAST PERIOD (TAU 72).
BETWEEN TAU 24 AND TAU 72, THE SPEED OF APPROACH WILL BEGIN
INCREASING SIGNIFICANTLY AS THE SYSTEM UNDERGOES EXTRATROPICAL
TRANSITION INTO THE END OF THE FORECAST. WITH REGARD TO INTENSITY,
TYPHOON HALONG IS FORECASTED TO MAINTAIN 120 KTS OVER THE NEXT 12
HOURS AS THE SYSTEM COMPLETES THE RECURVE PHASE OF THE FORECAST
TRACK WITHIN A LARGELY CONDUCIVE ENVIRONMENT. AFTER TAU 12, THE
SYSTEM WILL BEGIN ITS INITIAL DECAYING PHASE AS VWS STEADILY
INCREASES TO OVER 15 KTS. BY TAU 24, VWS IS EXPECTED TO EXCEED 30
KTS AT THE SAME TIME DRY AIR WRAPS INTO THE SOUTHERN SEMICIRCLE.
NEAR TAU 30, TY 28W WILL BEGIN EXTRATROPICAL TRANSITION AS STRONG
VWS, DRY AIR, AND COOLER SEA SURFACE TEMPERATURES QUICKEN THE
TERMINAL WEAKENING PHASE. BY TAU 72, TY 28W IS FORECASTED TO BECOME
FULLY EXTRATROPICAL WHILE MAINTAINING SURFACE INTENSITIES OF 45 KTS
UNDER THE INFLUENCE OF THE MID-LATITUDE UPPER-LEVEL JET.

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION GUIDANCE REMAINS IN
GREAT AGREEMENT THAT TY 28W WILL CONTINUE TO ROUND THE WESTERN
PERIPHERY OF THE SUBTROPICAL RIDGE TO THE EAST AND THEN BEGIN ITS
TERMINAL EAST-NORTHEASTWARD TRACK BETWEEN TAU 24 AND TAU 72. THE
CROSS-TRACK SPREAD AT TAU 36 IS JUST 33 NM, INCREASING STEADILY TO
97 NM BY TAU 72 AND INTO THE COMPLETION OF EXTRATROPICAL
TRANSITION. THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE
THROUGHOUT THE ENTIRETY OF THE FORECAST PERIOD AND ALIGNED CLOSELY
WITH THE JTWC CONSENSUS. MOST OF THE JTWC INTENSITY CONSENSUS
MEMBERS ARE IN GOOD AGREEMENT, ILLUSTRATING STEADY INTENSITIES OVER
THE NEXT 12 HOURS, AND A SHARP WEAKENING PHASE UNTIL THE END OF THE
FORECAST PERIOD. THE ONLY REMAINING OUTLIER IS HAFS, WHICH SHOWS
POTENTIAL INTENSIFICATION TO 125 KTS OVER THE NEXT 12 HOURS, AND A
WEAKENING PHASE THEREAFTER. THEREFORE, THE JTWC INTENSITY FORECAST
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE RATE OF DECAY AS
THE SYSTEM UNDERGOES EXTRATROPICAL TRANSITION. 

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