WDXS31 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN) WARNING 
NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1S 83.5E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 743 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN 8NM
PINHOLE EYE SURROUNDED BY TIGHTLY COILED BANDS OF DEEP CONVECTION.
AN ANALYSIS OF THE 89GHZ AND 37GHZ SSMIS COLOR COMPOSITE MICROWAVE
IMAGERY INDICATE THAT 05S REMAINS NEARLY AXISYMMETRIC WITH ONLY A
FEW NAUTICAL MILE DIFFERENCE BETWEEN LLCC AND ULCC. THESE MICROWAVE
IMAGES ALSO INDICATE THAT WHILE 05S HAS MAINTAINED A ROBUST EYE
WALL, FALLING SSTS AND DRY AIR ENTRAINMENT ARE ERODING ITS BANDING
FEATURES AND AS A RESULT THERE IS MINIMAL DEEP CONVECTIVE BANDS TO
THE NORTH OF THE LLCC. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON EIR AND SSMIS IMAGERY. THE INITIAL INTENSITY OF
95KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY DVORAK
INTENSITY ESTIMATES RANGING FROM T5.0 - T6.0 WHILE AUTOMATED
ESTIMATES LIKE CIMSS SATCON AND ADT REMAIN STEADFAST NEAR 105KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) CENTERED
FAR TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T6.0 - 115 KTS
   FMEE: T5.0 - 90 KTS
   CIMSS SATCON: 104 KTS AT 240828Z
   CIMSS ADT: 105 KTS AT 241215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: POLEWARD OUTFLOW CHANNEL INTO BASE OF 200MB TROF
TO THE SOUTHEAST.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE 05S (DORIAN) HAS RECENTLY
STEADIED UP ON A SOUTH-SOUTHEASTERLY HEADING UNDER THE RECENT
INFLUENCE OF A NEAR-EQUATORIAL RIDGE (NER) CENTERED TO THE
NORTHEAST. THOUGH THE OVERALL ENVIRONMENT REMAINS MARGINALLY
FAVORABLE, CHARACTERIZED BY LOW VERTICAL WIND SHEAR AND MODERATE
RADIAL OUTFLOW ALOFT, INCREASINGLY OFFSET BY FALLING SEA SURFACE
TEMPERATURES AND OCEAN HEAT CONTENT VALUES. HAVING SLOWED TO MAKE
ITS DRAMATIC POLEWARD TURN, 05S HAS UPWELLED A SIGNIFICANT AMOUNT
OF COOLER WATER, AS A RESULT INTENSITIES WILL GRADUALLY DECLINE
OVER THE NEXT 12 HOURS. BY TAU 24, AS THE SYSTEM REGAINS FORWARD
PROGRESS, 05S TRAVELS OVER A RELATIVELY WARM TONGUE OF SSTS THAT
WILL SLIGHTLY HAMPER THE WEAKENING TREND.  BY TAU 48, ALL BETS ARE
OFF AS 05S BEGINS TO EXIT THE WARM EXTENSION OF SSTS, WHICH WILL
HAVE A SIGNIFICANT NEGATIVE IMPACT ON THE INTENSITY TREND. AT THE
SAME TIME, 05S WILL TRANSITION STEERING INFLUENCE BACK TO THE
SUB-TROPICAL RIDGE (STR) TO THE SOUTH, WHICH WILL DIVERT 05S TO THE
SOUTHWEST AND DRASTICALLY INCREASE ITS TRACK SPEED. AS THE SYSTEM
IS PUSHED POLEWARD BY THE STR, INTENSITIES ARE FORECAST TO CONTINUE
TO FALL UNTIL REACHING AROUND 40KTS BY TAU 120.     

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH ALL
MEMBERS INDICATING A SOUTH-SOUTHEASTWARD TRACK THROUGH TAU 48,
AFTER WHICH A SOUTHWESTWARD TRACK THROUGH THE FORECAST PERIOD. FOR
THIS REASON THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE.
RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH ONLY
COAMPS-TC TAKING AN INTENSIFICATION TREND, AND HWRF TAKING AN
AGGRESSIVE WEAKENING TREND, WHILE THE BULK OF THE GUIDANCE, AND THE
JTWC FORECAST INTENSITY REMAINS NEAR THE CONSENSUS THROUGH THE
FORECAST PERIOD. FOR THIS REASON THE JTWC FORECAST INTENSITY IS
PLACED WITH MEDIUM CONFIDENCE. 

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