WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 29W (NAKRI) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 35.0N 154.6E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 649 NM NORTH OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 28 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
DESPITE ALREADY BEING THE INITIAL PHASES OF EXTRATROPICAL
TRANSITION (ETT) AND UNDER EXTREMELY HIGH WIND SHEAR, ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT TYPHOON (TY) 29W
REMAINS SURPRISINGLY WELL-ORGANIZED. WHILE THE EYE IS NO LONGER
EVIDENT IN THE MSI, THE MSI AS WELL AS ENHANCED EIR SHOW MODERATELY
STRONG CONVECTION SURROUNDING A SYMMETRIC INNER CORE. A 140253Z
AMSR2 PACKAGE SHOWED A WELL-DEFINED MICROWAVE EYE IN THE 89GHZ
CHANNEL, WITH MODERATE TO STRONG CONVECTION FOCUSED IN THE
NORTHEASTERN QUADRANT, AND WEAKER CONVECTION SURROUNDING THE
REMAINDER OF THE CORE. THE CONVECTION TO THE NORTHEAST IS BEGINNING
TO FORM A DELTA RAIN REGION, INDICATIVE OF THE ONSET OF ETT. THE
36GHZ IMAGE DEPICTS A WEAKER LOW-LEVEL MICROWAVE EYE OFFSET TO THE
SOUTHWEST OF THE UPPER-LEVEL EYE, AND A SIGNIFICANTLY ERODED CORE
STRUCTURE IN THE WESTERN HALF OF THE SYSTEM, INDICATING STRONG COLD
AND DRY AIR ADVECTION IN THAT PORTION OF THE CIRCULATION.
ATMOSPHERIC MOTION VECTORS (AMV) FROM CIMSS SHOW A BROAD REGION OF
DIVERGENT OUTFLOW INTO THE RIGHT REAR ENTRANCE REGION OF A 150 KNOT
JET MAX TO THE NORTHEAST, WHICH IS OFFSETTING THE OTHERWISE HIGHLY
UNFAVORABLE SHEAR CONDITIONS, AT LEAST FOR THE MOMENT, AND ALLOWING
THE SYSTEM TO MAINTAIN ITS STRUCTURE. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON AN EXTRAPOLATION OF THE
EARLIER AMSR2 IMAGE. REANALYSIS OF EARLIER SAR AND ASCAT DATA HAS
RESULTED IN A 15 KNOT INCREASE IN THE 18Z AND 00Z ANALYSES,
EXTRAPOLATION OF WHICH HAS LED TO A 70 KNOT INITIAL INTENSITY,
WHICH ALSO ALIGNS WELL WITH THE OBJECTIVE AND SUBJECTIVE INTENSITY
ESIMATES NOTED BELOW. OVERALL, ENVIRONMENTAL CONDITIONS ARE HIGHLY
UNFAVORABLE, WITH COOL SSTS, AND EXTREMELY HIGH SHEAR, OFFSET BY
THE ROBUST OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) COMPLEX TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 66 KTS AT 140600Z
   CIMSS ADT: 74 KTS AT 140530Z
   CIMSS AIDT: 77 KTS AT 140530Z
   CIMSS D-MINT: 70 KTS AT 140253Z
   CIMSS D-PRINT: 69 KTS AT 140600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30+ KTS
   SST: 24-25 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT, AND CONVERGENCE ALOFT. 

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: TYPHOON (TY) 29W WILL CONTINUE TRACKING
EASTWARD ALONG THE NORTHERN PERIPHERY OF A DEEP STR TO THE SOUTH,
THROUGH THE ENTIRETY OF THE SHORT FORECAST PERIOD. THE SYSTEM HAS
ALREADY BEGUN EXTRATROPICAL TRANSITION (ETT), WITH WARM
FRONTOGENESIS PARTICULARLY EVIDENT BY THE PRESENCE OF A DELTA RAIN
REGION IN THE LATEST MICROWAVE IMAGERY. RAPID COLD FRONTOGENESIS
AND DECAPITATION OF THE INNER VORTEX IS EXPECTED WITHIN THE NEXT 24
HOURS AS THE SYSTEM MOVES CLOSER TO THE MID-LATITUDE JET TO THE
NORTH AND IS SMOTHERED BY COOL, DRY AIR MOVING IN FROM THE WEST.
THE SYSTEM IS EXPECTED TO SLOWLY WEAKEN AS IT MOVES EASTWARD BUT
WILL COMPLETE ETT AS A STRONG STORM-FORCE TO WEAK TYPHOON-FORCE LOW
PRESSURE SYSTEM BY TAU 24.  

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
STRONG AGREEMENT, PROVIDING HIGH CONFIDENCE TO THE JTWC FORECAST
TRACK. INTENSITY GUIDANCE IS MORE MIXED, WITH THE HAFS-A INDICATING
A STEADY INTENSITY THROUGH TAU 12 BEFORE RAPIDLY WEAKENING, WHILE
THE REMAINDER OF THE GUIDANCE INDICATES A FASTER RATE OF WEAKENING.
THE JTWC FORECAST IS POSITIONED CLOSE TO THE CTCX MODEL WITH HIGH
CONFIDENCE. 

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