WDXS31 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07S (DIKELEDI) WARNING 
NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.9S 44.7E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 470 NM SOUTH-SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 07S (DIKELEDI) AS A COMPACT SYSTEM WITH AN EVIDENT BUT
DETERIORATING EYE-FEATURE. WHILE INTENSIFICATION HAS BEEN OBSERVED
OVER THE PAST 12 HOURS, WELL-DEFINED CONVECTIVE BANDING HAS WRAPPED
AROUND THE EASTERN PERIPHERY OF THE LOW-LEVEL CIRCULATION INTO THE
SOUTHERN QUADRANT AS THE NORTHERN SEMICIRCLE HAS BEGUN SHOWING
SIGNS OF INCREASED PRESSURE FROM THE NORTHWEST WITH A TIGHTER
BRIGHTNESS TEMPERATURE GRADIENT. ALOFT, STRONG POLEWARD OUTFLOW HAS
ALSO CONTINUED AS THE UPSTREAM LEG OF AN EQUATORWARD EXTENDING
LONGWAVE TROUGH HAS SUPPORTED INTENSIFICATION SINCE THE PREVIOUS
FORECAST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE AFOREMENTIONED OBSERVABLE, YET INCREASINGLY RAGGED
EYE-FEATURE ON ANIMATED MSI. THE INITIAL INTENSITY IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON AGENCY DVORAK ESTIMATES AND A 160230Z
SENTINEL-1 SAR IMAGE.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) DIRECTLY TO THE
EAST-SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T5.5 - 102 KTS
   FMEE: T5.5 - 102 KTS
   CIMSS ADT: 112 KTS AT 160630Z
   CIMSS AIDT: 115 KTS AT 160630Z
   CIMSS D-PRINT: 86 KTS AT 160630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: INTENSIFICATION OCCURRED OVER THE LAST
12 HOURS DUE TO A CONTINUED FAVORABLE ENVIRONMENT. INITIAL
INTENSITY IS ASSESSED AT 100 KTS. 

FORECAST DISCUSSION: TROPICAL CYCLONE 07S (DIKELEDI) IS FORECASTED
TO CONTINUE TO THE EAST-SOUTHEAST OVER THE NEXT 36 HOURS AROUND THE
SOUTHWEST AND SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE LOCATED
DIRECTLY TO THE EAST-SOUTHEAST. FOLLOWING TAU 36, THE SYSTEM IS
EXPECTED TO TRACK EASTWARD ALONG THE SOUTHERN EXTENT OF THE
SUBTROPICAL RIDGE AND INTO THE MID-LATITUDE WESTERLIES UNTIL
EXTRATROPICAL TRANSITION AT TAU 48. WITH REGARD TO INTENSITY, TC
07S IS FORECASTED TO BEGIN ITS INITIAL WEAKENING PHASE OVER THE
NEXT FEW HOURS AS THE SYSTEM TRACKS EAST-SOUTHEAST INTO COOLER
WATERS (LESS THAN 26 C), WITH EVENTUAL DISSIPATION DUE TO
BAROCLINIC TRANSITION. FROM THIS ANALYSIS, TC DIKELEDI IS EXPECTED
TO CONTINUE WEAKENING WITH SUSTAINED COOLER SEA SURFACE
TEMPERATURES AND INCREASED VWS ABOVE 20 KTS THROUGH THE REMAINDER
OF THE FORECAST PERIOD AT TAU 48. HOWEVER, STARTING AROUND TAU 24,
THE CYCLONE WILL BEGIN EXTRATROPICAL TRANSITION WITH INCREASED
INTERACTION WITH THE MIDLATITUDE WESTERLIES ASSOCIATED WITH THE
BAROCLINIC ZONE. BY TAU 48, TC 07S IS EXPECTED TO COMPLETE
EXTRATROPICAL TRANSITION AS THE SYSTEM BECOMES COMPLETELY EMBEDDED
WITHIN THE MIDLATITUDE WESTERLY FLOW YET SUSTAIN INTENSITIES OF 40
KTS AS A BAROCLINIC CYLONE.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE CONTINUES TO BE IN VERY
TIGHT AGREEMENT WITH A CROSS-TRACK SPREAD OF JUST 107 NM BY THE END
OF THE FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC TRACK
FORECAST. THE JTWC INTENSITY FORECAST REMAINS CLOSE TO THE
MULTI-MODEL INTENSITY CONSENSUS THROUGHOUT THE ENTIRE WEAKENING
PHASE OF TC 07S, WITH ALL MEMBERS INDICATING THE DECAY OF TC
DIKELEDI FROM TAU 0 TO TAU 48. THE INTENSITY FORECAST IS ASSESSED
WITH MEDIUM CONFIDENCE DUE TO THE EXPECTED EXTRATROPICAL TRANSITION
PHASE BEGINNING AT TAU 24.

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