WDPN31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 
012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.7N 152.2E
   INITIAL INTENSITY: 140 KTS
   GEOGRAPHIC REFERENCE: 435 NM EAST OF WFO GUAM 
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A NEARLY
SYMMETRICAL DEEP-CONVECTIVE CANOPY SURROUNDING THE WELL-DEFINED EYE
FEATURE OF SUPER TYPHOON (STY) 09W (BAVI). ENVIRONMENTAL ANALYSIS
REVEALS A HIGHLY FAVORABLE ENVIRONMENT WITH LOW (5-10 KTS) VERTICAL
WIND SHEAR (VWS), ROBUST UPPER-LEVEL, RADIAL OUTFLOW, WARM (29-30
C) SEA SURFACE TEMPERATURES (SST) AND PLENTY OF ATMOSPHERIC
MOISTURE AVAILABLE THROUGHOUT THE VERTICAL COLUMN. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANALYSIS OF A
20 NM DIAMETER EYE FEATURE. THE INITIAL INTENSITY OF 140 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE CONSISTENT DVORAK
INTENSITY ASSESSMENT AND OBJECTIVE AIDS LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: ELONGATED EASTERN EXTENSION OF A
DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED EAST OF TAIWAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T6.0 - 115 KTS
   RCTP: T7.0 - 140 KTS 
   KNES: T7.0 - 140 KTS 
   CIMSS SATCON: 125 KTS AT 031800Z
   CIMSS ADT: 146 KTS AT 031800Z
   CIMSS AIDT: 139 KTS AT 031800Z
   CIMSS D-PRINT: 135 KTS AT 031800Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: STY 09W IS FORECAST TO CONTINUE TRACKING
WESTWARD OVER THE NEXT 12-24 HOURS, WHILE SLIGHTLY SLOWING DOWN ITS
TRANSLATION SPEED DUE TO A MINOR SHIFT IN THE STEERING MECHANISM.
WHILE THE STR CENTERED TO THE NORTHEAST CURRENTLY REMAINS THE
PRIMARY MECHANISM, A PASSING LONGWAVE TROUGH TO THE NORTH IS
RESULTING IN A SPLIT OF THE BROAD RIDGING, WITH AXIS JUST TO THE
NORTH OF CURRENT POSITION OF STY BAVI. AS A RESULT, AFTER TAU 24,
THE SYSTEM IS EXPECTED TO TAKE ON A WEST-NORTHWESTWARD TRACK
THROUGHOUT THE CURRENT FORECAST PERIOD. WHILE STY 09W REMAINS IN
THIS WEAKER STEERING ENVIRONMENT, THE EXTREME INTENSIFICATION IS
EXPECTED TO SLIGHTLY COOL OFF, BUT THE SYSTEM IS FORECAST TO REACH
150 KTS WITHIN THE NEXT 24-36 HOURS. AFTERWARDS, AS IT ONCE AGAIN
GAINS SPEED, IT WILL BEGIN TO INTERACT WITH THE MARIANA ISLANDS,
WITH THE PASSAGE OF THE LOW-LEVEL CIRCULATION CENTER BETWEEN TAUS
48 AND 60. DURING THIS PHASE, STY 09W WILL VERY LIKELY MAINTAIN ITS
SUPER TYPHOON STRENGTH. AROUND THE SAME TIME, HAFS-A DEPICTS A
PROBABILITY OF AN EYEWALL REPLACEMENT CYCLE (ERC), WHICH INTRODUCES
ADDITIONAL UNCERTAINTY IN THE TIMING AND MAGNITUDE OF THE PEAK
INTENSITY. AS THE SYSTEM TRANSLATES WEST-NORTHWESTWARD, IT WILL BE
PUSHING AGAINST A DRY AIR MASS TO THE NORTHWEST. VWS IS EXPECTED TO
BEGIN INCREASING SHORTLY AFTER TAU 72, REACHING 25 KTS AT TAU 96.
AS A RESULT OF THOSE CHANGES IN ENVIRONMENTAL CONDITIONS, SOME
WEAKENING IS EXPECTED NEAR THE END OF THE CURRENT FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL PREDICTION IN REGARD TO THE TRACK
REMAINS IN VERY GOOD AGREEMENT, AS WITNESSED BY A CROSS-TRACK
SPREAD OF 48 NM AT THE TIME OF CPA TO TINIAN AND ROTA. THE OFFICIAL
JTWC TRACK IS PLACED WITH HIGH CONFIDENCE IN CLOSE PROXIMITY TO THE
MULTI-MODEL CONSENSUS, LEANING SLIGHTLY ON THE SOUTHERN SIDE AND
TOWARDS THE EXPERIMENTAL AI GUIDANCE. INTENSITY IS ASSESSED WITH
MEDIUM CONFIDENCE THROUGHOUT THE CURRENT FORECAST PERIOD. CURRENTLY
AVAILABLE GUIDANCE INDICATES CONTINUOUS MINOR INTENSIFICATION OVER
THE NEXT 24 HOURS, HOWEVER, THE INTENSITY PREDICTION SPREAD
INCREASES TO 55 KTS AROUND TAU 72. HAFS IS CURRENTLY THE MOST
AGGRESSIVE, PREDICTING A PEAK NORTH OF 160 KTS, WHILE DETERMINISTIC
GFS OSCILLATES AROUND 105-120 KTS THROUGHOUT THE REMAINDER OF THE
FORECAST. OFFICIAL JTWC PREDICTION IS LAID ON THE HIGHER SIDE OF
THE CONSENSUS, AS A RESULT OF FAVORABLE ENVIRONMENTAL CONDITIONS
PREDICTION.

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