WDPN31 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.3N 171.7E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 464 NM SOUTHEAST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
12W AS A RAPIDLY DEVELOPING SYSTEM ATTEMPTING TO FORM AN EYE. IN
ANIMATED BRIGHTNESS TEMPERATURE IMAGERY, A RAGGED PINHOLE EYE IS
EMBEDDED WITHIN -80C COLD CLOUD TOPS. IN THE 280605Z SSMIS
MICROWAVE DATA, A WELL-DEFINED MICROWAVE EYE IS PRESENT. GIVEN THE
RECENT RAPID INTENSIFICATION AND SATELLITE DATA, 12W IS EXPECTED TO
DEVELOP A CLEAR EYE WITHIN THE NEXT FEW HOURS. THE SLIGHTLY
ELEVATED MID- TO UPPER-LEVEL SHEAR PREVIOUSLY APPLYING PRESSURE TO
THE EASTERN FLANK APPEARS TO HAVE ABATED, AS 12W IS NOW MORE 
VERTICALLY STACKED (EVIDENCED BY THE 280605Z SSMIS DATA) AND IS 
DEVELOPING STRONG CONVECTION AND SPIRAL BANDING ALONG THE EASTERN 
PERIPHERY. 12W REMAINS IN AN EXCEPTIONALLY FAVORABLE ENVIRONMENT, 
DEFINED BY LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), WARM (29-30 KTS) 
SEA SURFACE TEMPERATURES (SST), AND ROBUST DUAL-CHANNEL OUTFLOW
ENHANCED BY AN UPPER-LEVEL POINT SOURCE OVER THE SYSTEM AND AN UPPER-
LEVEL CYCLONE TO THE NORTHEAST. THE INITIAL POSITION IS PLACED WITH 
HIGH CONFIDENCE BASED ON THE PINHOLE EYE PRESENT IN THE 280605Z SSMIS 
IMAGERY AND THE DIMPLE IN ANIMATED MSI. THE INITIAL INTENSITY OF 75 
KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 280638Z RCM-2 SAR 
PASS REVEALING 75-80 KTS SURROUNDING THE CORE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHERN FLANK OF AN EXPANSIVE
SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 59 KTS AT 280510Z
   CIMSS ADT: 77 KTS AT 280640Z
   CIMSS AIDT: 74 KTS AT 280640Z
   CIMSS D-MINT: 77 KTS AT 280605Z
   CIMSS D-PRINT: 68 KTS AT 280640Z

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

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: TY 12W (DOLPHIN) HAS COMMENCED ITS NORTHWESTWARD 
TURN AS THE STEERING RIDGE LOCATED TO THE NORTHEAST BEGINS TO WEAKEN 
AND RETREAT FURTHER NORTHEASTWARD. 12W IS FORECAST TO TRACK 
NORTHWESTWARD THROUGH THE DURATION OF THE FORECAST PERIOD, AS AN 
UPPER-LEVEL TROUGH FORCES THE STEERING STR TO RETREAT FURTHER 
NORTHEASTWARD AND REINFORCES THE NORTHWESTWARD TRACK. REGARDING 
INTENSITY, 12W IS EXPECTED TO REMAIN IN AN EXCEPTIONALLY FAVORABLE
ENVIRONMENT FOR THE DURATION OF THE FORECAST PERIOD, SUPPORTING
UNINHIBITED INTENSIFICATION. DOLPHIN IS FORECAST TO MAINTAIN ITS 
CURRENT RAPID INTENSIFICATION (RI) TREND, BUT COULD VERY EASILY 
INTENSIFY AT A MUCH QUICKER RATE AND UNDERGO EXTREMELY RAPID
INTENSIFICATION (EIR). AT THIS POINT, THE ONLY HINDERANCE TO DOLPHIN'S 
INTENSIFICATION IS PHYSICS. THE CURRENT JTWC FORECAST INDICATES A PEAK 
INTENSITY OF 150 KTS BETWEEN TAU 60-72 FOLLOWED BY SLIGHT WEAKENING. 
AS 12W INTENSIFIES, THE PROBABILITY OF IT EXPERIENCING AN EYEWALL 
REPLACEMENT CYCLE (ERC) INCREASES PARTICULARLY BEYOND TAU 48 LEADING 
TO UNPREDICTABLE INTENSITY FLUCTUATIONS THAT MAY NOT BE REFLECTED IN 
THE OFFICIAL FORECAST. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE REMAINS IN STRONG 
AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THE NEAR-TERM 
JTWC TRACK FORECAST. AFTER TAU 72, A HANDFUL OF OUTLYING MODELS EMERGE 
TO POLEWARD AND EQUATORWARD OF THE MAIN CLUSTER OF MODELS. THE 
POLEWARD OUTLIERS INCLUDE NAVGEM AND UKMET, WHILE THE EQUATORWARD 
OUTLIERS INCLUDE GSM AND EXPERIMENTAL AI GEFS. EXCLUDING THOSE 
OUTLIERS, THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE 
FROM TAU 72-120. RELIABLE INTENSITY AIDS CONTINUE TO HAVE A LARGE 
SPREAD IN BOTH RATE OF INTENSIFICATION AND PEAK INTENSITY. THE JTWC 
INTENSITY FORECAST LIES ON THE HIGHER END OF THE MODEL ENVELOPE, AND 
IN LINE WITH HAFS-A FOR THE FIRST 48 HOURS OF THE FORECAST. FOLLOWING 
TAU 48, THE JTWC INTENSITY FORECAST CLOSELY FOLLOWS COAMPS-TC (GFS 
BOUNDARY CONDITIONS), WHILE HAFS-A CONTINUES TO INTENSIFY THE STORM TO 
A PEAK OF 165 KTS. GIVEN THE PHENOMOENAL ENVIRONMENT AND EXPECTATION 
OF NEAR-EIR OR EIR, A PEAK INTENSITY GREATER THAN 150 KTS IS LIKELY 
(BARRING AN ERC SCENARIO, WHICH WOULD TEMPORARILY WEAKEN THE SYSTEM), 
AND INTENSIFICATION TO 165 KTS AS SHOWN IN HAFS-A IS WELL WITHIN THE 
REALM OF POSSIBILITY. AS A RESULT OF THE UNCERTAINTY SURROUNDING 
INTENSIFICATION AND THE LATE-TERM FORECAST, THE JTWC INTENSITY 
FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE FROM TAU 0-72 AND LOW 
CONFIDENCE FROM TAU 72-120.


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