WDXS31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07S (DIKELEDI) WARNING 
NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.7S 42.3E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 239 NM SOUTH-SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 19 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT TROPICAL CYCLONE THAT HAS INTENSIFIED OVER THE PAST 12
HOURS. AN EYE IS NOW EVIDENT IN EIR IMAGERY, THOUGH ONLY
INTERMITTENTLY. THE UNDERLYING EYEWALL STRUCTURE IS WELL-DEFINED,
CIRCULAR, AND CLOSED IN A 151841Z GMI MICROWAVE IMAGE, AND A 1543Z
RCM-1 SAR PASS REVEALS A COHERENT CORE WIND FIELD, STRONGEST IN THE
EASTERN SEMICIRCLE. UPPER-LEVEL POLEWARD OUTFLOW IS REACHING ITS
APEX AS A JET STREAK ENTRANCE REGION PASSES BY TO THE SOUTH. THE
INITIAL INTENSITY IS SET AT 85 KT BASED ON A BLEND OF AGENCY DVORAK
INTENSITY ESTIMATES AND OBJECTIVE SATELLITE-BASED INTENSITY
ESTIMATES, ALL RANGING FROM 77 TO 88 KT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE SOUTHEAST OF
MADAGASCAR

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T5.0 - 90 KTS
   CIMSS SATCON: 88 KTS AT 151612Z
   CIMSS ADT: 79 KTS AT 151800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE 07S (DIKELEDI) IS MOVING
QUICKLY SOUTHEASTWARD AROUND THE POLEWARD FLANK OF THE SUBTROPICAL
RIDGE TO ITS EAST. THE CYCLONE HAS TAKEN ADVANTAGE OF VERY WARM SEA
SURFACE TEMPERATURES (SST), STRONG UPPER-LEVEL OUTFLOW, AND A
COMPACT CORE WIND FIELD, RESULTING IN INTENSIFICATION OVER THE PAST
12 HOURS. SOME FURTHER INTENSIFICATION IS POSSIBLE OVER THE NEXT 12
HOURS, BUT DIKELEDI IS NOW CROSSING THE MERIDIONAL SST GRADIENT,
AND MAY BE OVER WATERS COOLER THAN 26 DEGREES CELSIUS BY 24 HOURS.
THE WINDOW FOR INTENSIFICATION IS THUS CLOSING QUICKLY, AND THE
CYCLONE MAY HAVE ALREADY PEAKED. THE JTWC INTENSITY FORECAST IS
FLAT FOR THE FIRST 12 HOURS, AND THEN SHOWS STEADY WEAKENING DUE TO
COOLER WATERS AND INCREASING VERTICAL SHEAR AS DIKELEDI APPROACHES
THE MID-LATITUDE JET. EXTRATROPICAL TRANSITION IS EXPECTED TO BEGIN
AROUND 36 HOURS AS THE CYCLONE INTERACTS WITH THE JET AND
ASSOCIATED BAROCLINIC ZONE, EVENTUALLY COMPLETING BY 72 HOURS. A
GRADUAL TURN IN STORM HEADING FROM SOUTHEASTWARD TO EASTWARD IS
EXPECTED AFTER 24 HOURS DUE TO MOSTLY ZONAL JET FLOW SOUTH OF THE
STORM DURING THAT TIME.

MODEL DISCUSSION: THE JTWC TRACK FORECAST IS JUST NORTH OF THE
MULTI-MODEL CONSENSUS, WHICH HAS SHIFTED 30-40 NM SOUTHWARD SINCE
THE PREVIOUS WARNING. CROSS-TRACK SPREAD IS TIGHT, BUT ALONG-TRACK
SPREAD GROWS SIGNIFICANTLY BY 72 HOURS AS THE CYCLONE APPROACHES
THE MID-LATITUDE JET. THE JTWC INTENSITY FORECAST IS CLOSE TO THE
MULTI-MODEL CONSENSUS DURING THE FORECAST PERIOD, WITH MEMBERS
AGREEING WELL ON TERMINAL DECAY OF THE CYCLONE.

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