WDPN31 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.7N 155.3E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 610 NM EAST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 09W (BAVI) IS UNDERGOING AN EPISODE OF RAPID 
INTENSIFICATION (RI), WITH AN INTENSITY INCREASE FROM 55 KNOTS AT 
1200Z TO 90 KTS WITHIN A 12-HOUR PERIOD. ANIMATED COMBINED VISUAL AND 
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A WELL-DEFINED EYE, 
WHICH ALTHOUGH PRESENTLY CLOUD-FILLED, IS EXHIBITING RAPID DIABATIC 
CLEARING. DEEP CONVECTIVE HOT TOWERS CONTINUE TO DEVELOP ON THE 
DOWNSHEAR-LEFT QUADRANT AND WRAP UPSHEAR, SUPPORTING THE STRUCTURAL 
COHESION OF THE EYE. A 022318Z GPM COLOR-ENHANCED 37GHZ MICROWAVE 
IMAGE REVEALED A SLIGHTLY OVAL EYE CONSTRAINED BY A WELL-DEFINED CYAN 
RING AND A SLIGHTLY OFFSET BAND OF DEEP CONVECTION BEGINNING TO FORM 
A SOLID EYEWALL. THE INITIAL POSITION IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON THE MICROWAVE SIGNATURE AND CORRESPONDING EYE IN
THE MULTISPECTRAL IMAGERY (MSI). THE INITIAL INTENSITY IS ASSESSED 
WITH MEDIUM CONFIDENCE, ALIGNED WITH THE AUTONOMOUS KNES DVORAK 
INTENSITY ESTIMATE OF T5.0 (90 KTS) BASED ON THE EXTREME RAPID 
INTENSIFICATION (ERI) CURRENTLY ONGOING. THE ENVIRONMENT REMAINS 
OPTIMAL FOR ADDITIONAL RI OR ERI, WITH LOW DEEP-LAYER VWS (NOW 
ESTIMATED BY CIMSS AT 8 KTS), VERY WARM SSTS, HIGH OHC EXCEEDING 110 
KJ PER CM3, AND STRONG RADIAL OUTFLOW ALOFT. 

INITIAL WIND RADII BASIS: PERSISTENCE AND OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) EXTENDING FROM SOUTH OF KYUSHU EASTWARD
INTO THE NORTHERN PACIFIC TO THE NORTH OF TY 09W. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 73 KTS AT 022230Z
   CIMSS ADT: 74 KTS AT 030030Z
   CIMSS AIDT: 80 KTS AT 030030Z
   CIMSS D-MINT: 68 KTS AT 021951Z
   CIMSS D-PRINT: 79 KTS AT 022330Z

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: 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: TYPHOON 09W IS NOW TRACKING NEARLY DUE WEST, AS 
THE STEERING MECHANISM HAS SHIFTED TO THE ELONGATED STR POSITIONED TO 
THE NORTH. OVER THE NEXT 24 HOURS, THE STEERING GRADIENT IS FORECAST 
TO SLACKEN IN RESPONSE TO THE PASSAGE OF A MID-LATITUDE TROUGH WELL 
TO THE NORTH, WHICH WILL DEGRADE THE STR. A SLOW WESTWARD TRANSLATION 
IS FORECAST THROUGH TAU 36 AS THE STEERING PATTERN REMAINS HIGHLY 
PERSISTENT DURING THIS TIMEFRAME. AFTER TAU 36, THE TRACK IS EXPECTED 
TO TRANSITION TO A WEST-NORTHWEST VECTOR AS RIDGING AMPLIFIES TO THE 
NORTHEAST OF TY 09W AND MERGES INTO AN ELONGATED REGION OF RIDGING 
EXTENDING FROM KYUSHU TO NEAR 20N150E. THE STEERING GRADIENT WILL 
REMAIN RELATIVELY WEAK UNTIL TAU 72, WHEN THE SYSTEM WILL RESUME 
ACCELERATION. PASSAGE THROUGH THE NORTHERN MARIANAS AND THE CLOSEST 
POINT OF APPROXIMATION TO THE ISLANDS IS FORECAST TO OCCUR IN THE 
LATE ZULU HOURS OF 05 JULY. THE TRACK FORECAST HAS SHIFTED SOUTHWARD 
AND NOW FORECASTS PASSAGE BETWEEN ROTA AND TINIAN. ADDITIONAL 
SOUTHWARD ADJUSTMENTS IN FUTURE FORECASTS REMAIN A HIGH PROBABILITY, 
DEPENDING UPON THE DURATION OF THE CURRENT WESTWARD VECTOR AND 
WHETHER THE SYSTEM EXHIBITS A WEST-SOUTHWESTWARD TRAJECTORY AS 
DEPICTED BY THE ECMWF. IN TERMS OF INTENSITY, THE SYSTEM HAS 
INITIATED ITS ERI TIMELINE. ENVIRONMENTAL CONDITIONS WILL REMAIN 
HIGHLY FAVORABLE FOR THE NEXT 48 HOURS, ALLOWING THE SYSTEM TO 
ACHIEVE A PEAK INTENSITY OF AT LEAST 150 KNOTS BY TAU 48. AN 
ACCELERATED PROGRESSION TO SUPER TYPHOON STATUS WILL HASTEN THE ONSET 
OF AN EYEWALL REPLACEMENT CYCLE (EWRC), THOUGH THE SPECIFIC TIMING, 
DURATION, AND IMPACT ON INTENSITY ARE CURRENTLY UNRESOLVED. BEYOND 
TAU 60, HOWEVER, EASTERLY SHEAR IS FORECAST TO INCREASE SHARPLY. 
WHILE THE SYSTEM WILL BE QUITE LARGE AND INTENSE AND WILL LIKELY 
MITIGATE THE ADVERSE EFFECTS OF THE SHEAR, THE PERSISTENT NATURE OF 
THE SHEAR WILL CONSTRAIN THE SYSTEM'S THERMODYNAMIC STRUCTURE, AND IT 
IS FORECAST TO WEAKEN SLOWLY AFTER TAU 72. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS FOR THE MOST PART TIGHTLY
CONSTRAINED, THE ONLY EXCEPTIONS BEING NAVGEM AND THE ECMWF WHICH
ARE OUTLIERS TO THE SOUTH, TAKING THE CENTER OVER OR JUST NORTH OF
GUAM. CROSS-TRACK SPREAD BETWEEN THE NAVGEM ON THE SOUTH AND
ECWMF-AIFS ON THE NORTH IS 95NM, WHILE THE REMAINDER OF THE
GUIDANCE PACKAGE IS CONTAINED IN A TIGHT 25NM ENVELOPE, WHICH AS A
WHOLE HAS SHIFTED SOUTHWARD ABOUT 30NM. CROSS-TRACK SPREAD
GRADUALLY INCREASES AFTER TAU 72 TO 135NM. THE JTWC FORECAST IS
PLACED NEAR THE EXPERIMENTAL GDM FGNI TRACKER, ON THE SOUTHERN EDGE
OF THE INNER MODEL GROUPING WITH HIGH CONFIDENCE. INTENSITY
GUIDANCE IS IN GOOD OVERALL AGREEMENT, WITH A RANGE OF POTENTIAL
PEAK INTENSITIES BETWEEN 120 KNOTS ON THE LOW END (COAMPS-TC NAVGEM
AND HWRF) AND 145 KNOTS ON THE HIGH END (HAFS-A, GDM FGNI). NEARLY
EVERY RI AID CONTINUES TO TRIGGER, WITH HIGH PROBABILITIES
EXCEEDING 80 PERCENT. THE JTWC FORECAST IS PLACED AMONGST THE RI
AIDS AND FGNI TRACKER THROUGH TAU 48, THEN LOOSELY TRACKS THE
HAFS-A. UNCERTAINTY REGARDING THE TIMING OF ONSET, DURATION AND
IMPACT OF POTENTIAL EWRC RESULTS IN A LOW CONFIDENCE INTENSITY
FORECAST AFTER TAU 72. 

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