WDXS32 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 12S (ELVIS) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.8S 43.2E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 271 NM SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ALTHOUGH THERE IS A SMALL AND TIGHT UPPER LEVEL TROF OVER ELVIS,
ALL OTHER TRAITS OF THE SYSTEM REVEAL A BAROTROPIC NATURE. THERE IS
A TIGHT AND SYMMETRICAL 850MB VORTICITY FIELD OVER THE LOW LEVEL
CIRCULATION CENTER (LLCC) AND THE RADIUS OF MAXIMUM WINDS HAS
TIGHTENED OVER THE PAST 24 HOURS. MODELED SOUNDINGS SHOW SATURATION
THROUGH 15KFT AND THE CIMSS TOTAL PRECIPITABLE WATER CONFIRM THAT
THERE IS PLENTY OF DEEP MOISTURE ALONG TRACK. THE SYSTEM HAS BECOME
MORE COMPACT WITH TIME AND DVORAKS HAVE RISEN TO T3.O USING THE
TIGHTLY CURVED BAND METHOD WHILE OBJECTIVE ASSESSMENTS FROM CIMSS
ARE ALSO INCREASING. THE LATEST ADT IS UP TO 43KTS. THE DEEPEST
CONVECTION HAS BEEN SHEARED TO THE SOUTHEAST DUE TO OVER 20 KNOTS
OF VERTICAL WIND SHEAR (VWS) IN THE COLUMN BUT A TIGHT NUGGET OF
DEEP CONVECTION HAS PERSISTED AND CONSOLIDATED OVER THE CORE.
MOVEMENT HAD BEEN ERRATIC BUT OVER THE PAST TWO FIXES THE SYSTEM
HAS SETTLED INTO A SLOW SOUTHEASTWARD TRACK. PLENTY OF WARM WATER
EXISTS ALONG TRACK, WITH SEA SURFACE TEMPERATURES HOLDING ABOVE 26C
ALL THE WAY THROUGH THE 30TH LATITUDE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: THE SOUTHERN FLANK OF A RIDGE EXTENDING
OVER MADAGASCAR IS FORCING THE SYSTEM ALONG A SOUTHEASTWARD TRACK. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 43 KTS AT 291800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST PHILOSOPHY SCENARIO HAS
SWITCHED FROM SUBTROPICAL TRANSITION TO EXTRA-TROPICAL TRANSITION. 

FORECAST DISCUSSION: ELVIS IS ROLLING OUT OF THE TROPICS AND HEADED
TOWARDS A SMOOTH AND SLOW MERGE INTO THE ROARING FORTIES. VWS WILL
EASE A BIT DURING THE NEXT 48 HOURS BEFORE JUMPING TO OVER FORTY
KNOTS AS THE SYSTEM FUSES WITH THE MID-LATITUDE JET. SEA SURFACE
TEMPERATURES WILL REMAIN SUPPORTIVE THROUGH THE FIRST 36 HOURS BUT
THEN FALL AFTERWARDS.  BY THE TIME THE SYSTEM CROSSES THE 35TH
LATITUDE IT WILL BE WELL INTO THE EXTRA-TROPICAL TRANSITION PROCESS
AND BY TAU 48 IT WILL HAVE TRANSITIONED INTO A MID-LATITUDE LOW
PRESSURE SYSTEM. 

MODEL DISCUSSION: TRACK GUIDANCE IS TIGHT ENABLING JTWC TO RIDE THE
MULTI-MODEL CONSENSUS. INTENSITY GUIDANCE IS ALSO CONSISTENT WITH
NO MAJOR OUTLIERS AND KEEP THE SYSTEM AT GALE FORCE THROUGH ITS
LIFECYCLE. THE INTENSITY FORECAST FOLLOWS STATISTICAL-DYNAMICAL
GUIDANCE TO REFLECT PEAK INTENSITY NEAR TAU 24. 

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