WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 12W (DOLPHIN) WARNING NR
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.4N 165.7E
   INITIAL INTENSITY: 140 KTS
   GEOGRAPHIC REFERENCE: 181 NM SOUTH-SOUTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SUPER
TYPHOON 12W (DOLPHIN) WITH A HIGHLY SYMMETRICAL CENTRAL DENSE
OVERCAST SURROUNDING A WARM 15 NM EYE. THE CLOUD TOPS HAVE WARMED
OVER THE PAST 6 HOURS, AND IS ATTRIBUTED TO A LIKELY ONGOING
EYEWALL REPLACEMENT CYCLE (ERC). THE ABSENCE OF RECENT MICROWAVE
IMAGERY MEANS THAT THE ERC CANNOT BE CONFIRMED AND THE EXTENT TO
WHICH THE PROCESS HAS PROGRESSED REMAINS UNCERTAIN. A 291843Z RCM-2
SAR IMAGE REVEALED A VMAX OF ABOUT 143 KTS WITHIN THE WESTERN
PORTION OF THE EYEWALL. THE INITIAL INTENSITY OF 140 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SAR DATA IN
COMBINATION WITH THE AGENCY DVORAK AND CIMSS OBJECTIVE INTENSITY
ESTIMATES LISTED BELOW. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE DEFINED EYE IN ANIMATED MSI. THE
ENVIRONMENT CONTINUES TO BE CHARACTERIZED AS HIGHLY FAVORABLE DUE
TO STRONG RADIAL OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR,
AND WARM (29-30 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: 291843Z RCM-2 SAR DATA

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) CENTERED TO THE WEST OF HAWAII


AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T7.5 - 155 KTS
   RJTD: T7.0 - 140 KTS
   RCTP: T7.5 - 155 KTS
   KNES: T7.5 - 155 KTS
   PHFO: T7.5 - 155 KTS
   CIMSS ADT: 155 KTS AT 300000Z
   CIMSS AIDT: 145 KTS AT 300000Z
   CIMSS D-MINT: 140 KTS AT 292313Z
   CIMSS D-PRINT: 145 KTS AT 300000Z

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: HIGH

3. FORECAST REASONING.

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

FORECAST DISCUSSION: STY 12W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST
THROUGH TAU 72. AFTER TAU 72, 12W IS FORECAST TO TURN MORE WESTWARD
AS A LARGE RIDGE BUILDS AND ANCHORS TO THE NORTHWEST OF HAWAII.
NEAR TAU 120, A SEPARATE STR IS EXPECTED TO BUILD OVER THE SEA OF
JAPAN, EVENTUALLY BECOMING THE PRIMARY STEERING MECHANISM AT THE
END OF THE FORECAST PERIOD. IN TERMS OF INTENSITY, 12W IS FORECAST
TO MAINTAIN INTENSITY THROUGH TAU 24 AS THE ERC CONTINUES, AS
INDICATED BY EARLIER MICROWAVE IMAGERY. AFTER TAU 24, MARGINAL
INTENSIFICATION IS FORECAST TO OCCUR THROUGH TAU 48 AS THE SYSTEM
ATTEMPTS TO RECOVER FROM THE ERC AND REMAINS PLACED WITHIN A HIGHLY
FAVORABLE ENVIRONMENT. NEAR TAU 60, THE POLEWARD OUTFLOW CHANNEL
BECOMES RESTRICTED AND OCEAN HEAT VALUES BEGIN TO LOWER. THESE TWO
FACTORS, ALONG WITH AN EXPANDING WIND FIELD, WILL CAUSE 12W TO
GRADUALLY WEAKEN THROUGH THE END OF THE FORECAST PERIOD AS IT
TRACKS OFF TO THE WEST.


MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE CONTINUES TO BE IN
VERY GOOD AGREEMENT WITH A CROSS-TRACK SPREAD OF 80 NM AT TAU 72
AND 150 NM AT TAU 120. UKMET AND JGSM MAKE UP THE FURTHEST
EQUATORWARD TRACKERS WHILE THE GFS ENSEMBLE MEAN MAKES UP THE
NORTHERNMOST TRACKER THIS MODEL RUN. THE JTWC TRACK FORECAST IS
PLACED CLOSE TO THE MULTI-MODEL CONSENSUS THROUGHOUT THE FORECAST
PERIOD WITH OVERALL HIGH CONFIDENCE. INTENSITY GUIDANCE HAS BECOME
LESS AGGRESSIVE WHEN COMPARED TO THE PREVIOUS MODEL RUN, WITH ALL
MODELS NOW SHOWING A GENERALLY STABLE INTENSITY THROUGH TAU 48
FOLLOWED BY GRADUAL WEAKENING THROUGH TAU 120. THE JTWC INTENSITY
FORECAST NOW CALLS FOR A PEAK INTENSITY OF 145 KTS, CLOSE TO THE
COAMPS-TC DEPICTION WITH MEDIUM CONFIDENCE. THE UNCERTAINTY
REVOLVING AROUND THE TIMING OF THE COMPLETION OF THE ERC AND HOW
12W IS ABLE TO RECOVER FROM THE EVENT CAUSES THERE TO BE SOME
INCREASED AMBIGUITY IN THE NEAR-TERM INTENSITY FORECAST.

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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