WDPN31 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.7N 169.9E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 386 NM SOUTH-SOUTHEAST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 41 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ONE WORD: STUNNING. TYPHOON (TY) 12W HAS UNDERGONE A REMARKABLE
PERIOD OF EXPLOSIVE INTENSIFICATION, ADDING 80 KTS TO ITS MAXIMUM
SUSTAINED WIND IN THE PAST 24 HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS A COMPACT STORM FEATURING A
5-NM-WIDE PINHOLE EYE EMBEDDED WITHIN A SYMMETRIC CENTRAL DENSE
OVERCAST (CDO). AT ITS PEAK PRESENTATION, THE EYE WARMED TO +06
DEGREES CELSIUS, SURROUNDED BY CLOUD TOP TEMPERATURES COLDER THAN
-80 DEGREES CELSIUS. THE VIGOR OF THE CIRCULATION IS WELL
MANIFESTED IN THE OBSERVED TROCHOIDAL MOTION. THE INTENSE UPDRAFTS
IN THE EYEWALL HAVE GOOD POLEWARD VENTILATION INTO A SUBTROPICAL
JET STREAM ALONG 22N LATITUDE. THE ENVIRONMENT REMAINS HIGHLY
FAVORABLE, CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES (SST) OF
29-30 DEGREES CELSIUS AND HIGH OCEAN HEAT CONTENT (OHC) OF 125 KJ
PER CM2. THESE FACTORS ARE SLIGHTLY OFFSET BY LOW TO MODERATE
SOUTHEASTERLY VWS IN THE 500-300 MB LAYER. RECENT SATELLITE TRENDS
SUGGEST THE SYSTEM HAS TEMPORARILY HALTED ITS INTENSIFICATION, WITH
THE EYE TEMPERATURE COOLING AND THE CLOUD TOPS WARMING SLIGHTLY.
THIS, COMBINED WITH THE OBSERVED WOBBLE, SIGNALS THE INITIAL STAGES
OF AN EYEWALL REPLACEMENT CYCLE (ERC). A 281418Z AMSR2 PASS
SUPPORTS THIS POSSIBILITY, REVEALING A TINY INNER CORE PARTIALLY
WRAPPED BY AN INTENSE OUTER SPIRAL BAND. THE TIMING AND IMPACT OF
THE POTENTIAL ERC ARE LESS CERTAIN. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE WELL-DEFINED PINHOLE
EYE. THE INITIAL INTENSITY IS RAISED TO 125 KTS WITH MEDIUM
CONFIDENCE BASED ON THE DATA T-NUMBER OF 6.5 SUSTAINED OVER THE
PAST SEVERAL HOURS AND IS SUPPORTED BY THE SUBJECTIVE DVORAK
ESTIMATES OF T6.5 FROM PGTW AND KNES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A
DEEP-LAYER SUBTROPICAL RIDGE (STR) COMPLEX OVER THE CENTRAL NORTH
PACIFIC

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T6.5 - 127 KTS
   PHFO: T5.5 - 102 KTS
   CIMSS SATCON: 101 KTS AT 281430Z
   CIMSS ADT: 115 KTS AT 281800Z
   CIMSS AIDT: 113 KTS AT 281800Z
   CIMSS D-MINT: 104 KTS AT 281418Z
   CIMSS D-PRINT: 112 KTS AT 281800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST INTENSITY IN THE NEAR
TERM NOW DEPICTS SOME WEAKENING.

FORECAST DISCUSSION: TY 12W HAS TURNED TOWARDS THE NORTHWEST WITH
AN AVERAGE FORWARD SPEED OF 7-9 KTS, A MOTION THAT WILL PERSIST
THROUGH TAU 96 UNDER THE STEERING INFLUENCE OF A RIDGE COMPLEX OVER
THE CENTRAL NORTH PACIFIC. FOR THE FIRST 96 HOURS, THE SYSTEM WILL
MOVE TOWARD A WEAKNESS IN THE STR CREATED BY A LONGWAVE TROUGH
LOCATED EAST OF HONSHU. TOWARDS THE END OF THE FORECAST PERIOD, THE
TROUGH WILL WEAKEN, ALLOWING THE STR TO REBUILD NORTH OF TY 12W AND
INDUCE A SLIGHTLY MORE WESTWARD MOTION. THE SYSTEM APPEARS TO HAVE
REACHED AN INITIAL PEAK INTENSITY NEAR SUPER TYPHOON (STY) STATUS
BETWEEN 281500Z AND 281800Z. THE INTENSITY FORECAST ANTICIPATES
SOME INITIAL WEAKENING BETWEEN TAU 0 AND TAU 12 AS A RESULT OF THE
ONGOING ERC. THE FORWARD MOTION HAS ALSO SLOWED TO 6 KTS IN THE
PAST 3 HOURS. IF IT DOES NOT REGAIN FORWARD SPEED SOON, THEN THE
RISK OF UPWELLING OF COOLER OCEAN WATERS WILL INCREASE, FURTHER
HINDERING DEVELOPMENT. ONCE THE ERC COMPLETES, HOWEVER, TY 12W WILL
UNDERGO ANOTHER ROUND OF SIGNIFICANT INTENSIFICATION. THE SYSTEM
WILL TRAVERSE OVER EXCEPTIONALLY WARM SST OF 31-32 DEGREES CELSIUS
WITHIN A LOW-SHEAR ENVIRONMENT. THE FORECAST DEPICTS STEADY TO
RAPID INTENSIFICATION TO A SECOND, HIGHER PEAK OF 155 KTS AT TAU
48. THIS AND ANY SUBSEQUENT ERC EVENTS LEAD TO LESS PREDICTABLE
FLUCTUATIONS IN INTENSITY AND EXPANSION OF THE WIND FIELD.

MODEL DISCUSSION: THE GUIDANCE ENVELOPE IS RATHER TIGHT THROUGH TAU
96, WITH A CROSS-TRACK SPREAD OF 110 NM ONCE NAVGEM IS EXCLUDED AS
A POLEWARD OUTLIER. THE SPREAD INCREASES TO NEARLY 200 NM AT TAU
120, DRIVEN BY A DIVERGENCE IN THE EVENTUAL WESTWARD TURN. THE GEFS
AND UKMET ENSEMBLE MEANS FAVOR A LONGER CONTINUATION OF THE
NORTHWESTWARD TRAJECTORY, WHILE THE ECMWF AND GFS MODELS PROJECT AN
EARLIER WESTWARD TURN. THE JTWC FORECAST TRACK, WHICH IS VIRTUALLY
UNCHANGED THROUGH TAU 60, IS POSITIONED NEAR THE MULTI-MODEL
CONSENSUS UP TO TAU 60 AND THEN HEDGES TOWARDS THE MORE WESTWARD
SOLUTIONS. THE RELIABLE INTENSITY AIDS CONTINUE TO SHOW
INTENSIFICATION. HAFS-A REMAINS THE STRONGEST SOLUTION WITH A PEAK
OF 170 KTS. THE JTWC INTENSITY FORECAST TEMPORARILY DEVIATES FROM
THIS IMMEDIATE UPWARD TREND TO ACCOUNT FOR THE ERC. AFTER TAU 24,
THE FORECAST SHOWS THE SYSTEM REBOUNDING SHARPLY TO 155 KTS, WHICH
IS BETWEEN THE HAFS-A AND COAMPS-TC OUTPUT AND IS CLOSEST TO THE
EXPERIMENTAL GOOGLE DEEPMIND MODEL. THE INTENSITY AIDS SHOW SLIGHT
WEAKENING IN THE EXTENDED FORECAST PERIOD, LIKELY DUE TO A
COMBINATION OF ADDITIONAL ERC EVENTS, THE STRUCTURAL EFFECTS OF
WIND FIELD EXPANSION, AND DECREASING OHC.

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