WDPS32 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 16P (KEVIN) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.6S 179.6E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 455 NM SOUTH OF SUVA, FIJI
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 23 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 16P (KEVIN) CONTINUES TO RAPIDLY WEAKEN AND HAS BEGUN
SUBTROPICAL TRANSITION (STT). ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) AS WELL AS ENHANCED INFRARED (EIR) IMAGERY SHOWS THE
SYSTEM IS BEGINNING TO DECOUPLE, WITH THE LOW LEVEL CIRCULATION
CENTER (LLCC) STARTING TO LAG BEHIND THE MID AND UPPER-LEVEL
ROTATION, WHICH IS RACING TO THE SOUTHEAST. THE OUTER BANDS OF THE
LLCC ARE STARTING TO PEAK OUT FROM UNDER THE CONVECTIVE CANOPY AND
PROVIDED GOOD SUPPORT FOR PLACEMENT OF THE INITIAL POSITION A BIT
BEHIND THE PGTW FIX POSITION. A 042105Z AMSU-B 89GHZ MICROWAVE
IMAGE REVEALED WELL-ORGANIZED LOW-LEVEL BANDS WRAPPING INTO THE
CENTER FROM THE NORTH, WITH MORE VIGOROUS CONVECTIVE BANDING
FEATURES DRAPED ACROSS THE SOUTHERN PERIPHERY. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE AT 90 KNOTS, WHICH IS
RIGHT IN THE MIDDLE BETWEEN THE AGENCY DVORAK FINAL-T (FT) AND
CURRENT INTENSITY (CI) ESTIMATES (T4.5 AND T5.5 RESPECTIVELY) AND
CLOSE THE AIDT ESTIMATE OF 88 KNOTS. THE ENVIRONMENT IS
DETERIORATING FAST, CHARACTERIZED BY HIGH VWS, AND MODEST SSTS
OFFSET BY VERY STRONG POLEWARD OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   ABRF: T4.5 - 77 KTS
   CIMSS ADT: 94 KTS AT 042330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30+ KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: THE FORECAST HAS BEEN TRUNCATED TO 24 HOURS,
DURING WHICH TIME TC 16P IS EXPECTED TO TRANSITION TO A STORM-FORCE
SUBTROPICAL LOW. THE SYSTEM WILL RAPIDLY TRACK SOUTHEASTWARD ALONG
THE SOUTHWEST SIDE OF THE STRONG STR CENTERED FAR TO THE NORTH,
THROUGH THE SHORT FORECAST PERIOD. STT HAS ALREADY BEGUN AS THE
SYSTEM HAS BEGUN TO BE DECAPITATED BY STEADILY INCREASING WESTERLY
SHEAR. VERY DRY AIR TO THE WEST IS ALSO BEGINNING TO MOVE EVER
CLOSER TO THE CENTER AND WILL SOON ENGULF TC 16P, EFFECTIVELY
PUTTING AN END TO THE SYSTEM AS A TROPICAL CYCLONE. BY TAU 24, ALL
THAT WILL REMAIN OF TC 16P WILL BE A LOW-LEVEL NAKED VORTEX, WHICH
WILL RETAIN SIGNIFICANT INERTIA WHICH WILL TAKE TIME TO SPIN DOWN
AND IN THE FUTURE THE SYSTEM WILL LIKELY LINGER AS A GALE-FORCE
SUBTROPICAL LOW THAT EVENTUALLY TRANSITIONS TO AN EXTRATROPICAL
LOW. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN VERY GOOD AGREEMENT THOUGH
THE SHORT DURATION OF THE FORECAST, WITH VERY LITTLE IN THE WAY OF
EITHER CROSS OR ALONG-TRACK SPREAD, LENDING HIGH CONFIDENCE TO THE
JTWC FORECAST TRACK. ALL MEMBERS OF THE INTENSITY CONSENSUS CONCUR
ON SHARP WEAKENING THROUGH THE FORECAST PERIOD AND THE JTWC
FORECAST LIES ON THE HIGHER END OF THE ENVELOPE WITH HIGH
CONFIDENCE. 

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