WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (MALAKAS) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.1N 135.4E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 618 NM SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
WHILE TY MALAKAS CONTINUES TO INTENSIFY, THE RATE AT WHICH IT IS
DOING SO HAS SLOWED A BIT SINCE THE PREVIOUS ANALYSIS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT THE EYEWALL
HAS WIDENED A BIT, NOW ESTIMATED AT ROUGHLY 30NM WIDE, AND REMAINS
RELATIVELY RAGGED IN APPEARANCE. ONCE AGAIN HOWEVER, IMAGERY
SUBSEQUENT TO ANALYSIS TIME SUGGESTS THAT AN INNER, MUCH SMALLER,
EYE MAY BE TRYING TO FORM. UNFORTUNATELY THERE HAS BEEN NO RECENT
MICROWAVE IMAGERY TO ASSIST IN DETERMINING THE CORE STRUCTURE,
THOUGH A 121234Z ASCAT-B PASS DID REVEAL A WEAKER, MORE FRAGMENTED
WIND FIELD ON THE NORTHERN SIDE WHICH LINES UP WITH THE FRAGMENTED
EYE SEEN IN THE EIR. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE, AMONGST THE TIGHT GROUPING OF AGENCY FIX POSITIONS, IN
THE CENTER OF THE LARGE EYE. THE INITIAL INTENSITY OF 95 KNOTS IS
ASSESSED WITH MEDIUM CONFIDENCE, SLIGHTLY HIGHER THAN THE MAJORITY
OF THE OBJECTIVE DVORAK INTENSITY ESTIMATES, HEDGED HIGHER BASED ON
THE ADT AND THE AIDT OF 93 KNOTS. THE ENVIRONMENT REMAINS HIGHLY
FAVORABLE, WITH LOW DEEP-LAYER VWS, ROBUST DUAL CHANNEL OUTFLOW AND
WARM SSTS. WHILE THE DEEP-LAYER SHEAR IS LOW, HWRF CROSS-SECTIONS
REVEAL SOME ENHANCED MID-LEVEL NORTHERLY SHEAR AS WELL AS A POCKET
OF RELATIVELY DRY AIR SITUATED TO THE NORTH, WHICH SEEMS TO BE BORN
OUT IN THE EIR IMAGERY. OHC VALUES ARE ALSO RELATIVELY LOW IN THIS
AREA, WHICH COULD BE IMPARTING A LIMITING FACTOR TO THE
INTENSIFICATION TREND AS THE SYSTEM HAS SLOWED OVER THE LOW OHC
EDDY.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 99 KTS AT 121140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG DUAL-CHANNEL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY MALAKAS HAS ROUNDED THE RIDGE AXIS AND HAS
TURNED THE WHEEL OVER TO STEADY UP ON A NORTHEASTWARD TRACK. OVER
THE NEXT FEW HOURS IT IS EXPECTED TO START TO PICK UP SPEED AND
WILL CONTINUE TO ACCELERATE NORTHEASTWARD THROUGH THE DURATION OF
THE FORECAST PERIOD ALONG THE WESTERN SIDE OF THE STR TO THE EAST.
THE SYSTEM IS EXPECTED TO MAKE A CLOSE CPA TO IWO TO AROUND TAU 60,
BEFORE PUTTING UP THE FLANK BELL AND MAKING A RAPID EXIT INTO THE
BAROCLINIC ZONE NORTHEAST OF JAPAN. THE OVERALL ENVIRONMENT REMAINS
HIGHLY CONDUCIVE TO FURTHER INTENSIFICATION, WITH THE
AFOREMENTIONED CONDITIONS PERSISTING THROUGH THE NEXT 18-24 HOURS.
AS WILL BE DISCUSSED IN MORE DETAIL BELOW, THE GUIDANCE HAS COME
WAY DOWN WITH THE CURRENT MODEL RUN, HOWEVER BASED ON THE FACT THAT
THE ENVIRONMENT REMAINS GOOD AND THE SYSTEM SHOULD START TO PICK UP
SPEED WHILE MOVING OVER A HIGHER OHC EDDY, IT SHOULD BE ABLE TO
STEADILY INTENSIFY FOR A BIT LONGER BEFORE CONDITIONS DETERIORATE.
THE CURRENT FORECAST CALLS FOR A BIT LOWER PEAK OF 115 KNOTS BY TAU
24, BEFORE SHEAR WILL BEGIN TO INCREASE. BY TAU 48, SHEAR WILL BE
NORTH OF 35 KNOTS AND THE SYSTEM WILL BEGIN TO DECOUPLE AND RAPIDLY
WEAKEN. BETWEEN TAU 48 AND 72, SIGNIFICANT LOW TO MID-LEVEL DRY AIR
WILL PUNCH INTO THE CORE AND THE CIRCULATION WILL BEGIN TO DEVELOP
INCREASED BAROCLINICITY WHILE MOVING OVER COOLER WATERS, MARKING
THE BEGINNING OF EXTRATROPICAL TRANSITION (ETT). TY MALAKAS IS
FORECAST TO TRANSITION TO A STORM-FORCE EXTRATROPICAL LOW WITH AN
EXPANSIVE WIND FIELD NO LATER THAN TAU 96.  

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS
TIGHT CROSS-TRACK AGREEMENT THROUGH THE FORECAST PERIOD, WITH
MINIMAL SPREAD AT TAU 72, INCREASING TO A MODEST 250NM BY TAU 96.
NOT UNEXPECTEDLY FOR AN ACCELERATING RECURVING SYSTEM, ALONG-TRACK
SPREAD INCREASES FAIRLY DRAMATICALLY AFTER TAU 36, FROM 250NM TO
550NM BY THE END OF THE FORECAST PERIOD. THE JTWC TRACK LIES FAIRLY
CLOSE TO THE CONSENSUS MEAN THOUGH THE FORECAST WITH HIGH
CONFIDENCE THROUGH TAU 72 AND MEDIUM THEREAFTER DUE TO THE
INCREASED ALONG-TRACK SPREAD. INTENSITY GUIDANCE HAS COME WAY DOWN
FROM THE PREVIOUS FORECAST, WITH NONE OF THE RAPID INTENSIFICATION
AIDS TRIGGERING ON THIS CYCLE. THE HWRF NOW IS THE HIGHEST
INTENSITY AID, PEAKING AT JUST 105 KNOTS. THIS SEEMS UNLIKELY, WITH
THE CONTINUED EYE DEVELOPMENT. HENCE THE JTWC FORECAST LIES WELL
ABOVE THE GUIDANCE ENVELOPE THROUGH TAU 24, THEN CATCHES UP WITH
THE BULK OF THE GUIDANCE ON THE WAY DOWN BY TAU 48. CONFIDENCE IS
MEDIUM IN THE INTENSITY FORECAST. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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