WDXS31 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN) WARNING 
NR 027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.4S 69.1E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 814 NM SOUTHEAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) AND IMPROVED POLEWARD
OUTFLOW. A 301111Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS TIGHTLY
WRAPPING LOW LEVEL CLOUD LINES WITH DEEP CONVECTION TO THE SOUTH
BEING DRIVEN POLEWARD BY THE APPROACHING JET TO THE SOUTH. A
300928Z AMSR2 MICROWAVE RADIOMETER PASS REVEALS A FIELD OF 50 KNOT
WINDS HAS ONCE AGAIN REFORMED TO THE SOUTH OF THE LLCC. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND SSMIS
IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON RECENT AMSR2 RADIOMETER DATA.

INITIAL WIND RADII BASIS: 300928Z AMSR2 MICROWAVE RADIOMETER

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   FMEE: T2.5 - 35 KTS
   FIMP: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 300901Z
   CIMSS ADT: 30 KTS AT 300915Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 24-25 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: SUB-TROPICAL TRANSITION (STT) AND EVENTUAL
EXTRA-TROPICAL TRANSITION (ETT)

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 05S DARIAN HAS BEGUN TO TRANSITION INTO A
SUB-TROPICAL CYCLONE. BY TAU 12 AS IT CONTINUES TO ROUND THE
SUB-TROPICAL RIDGE TO THE EAST-NORTHEAST IT WILL COMPLETE STT AND
BEGIN ETT. AFTER TAU 36 AND BY TAU 48, NOW FULLY EMBEDDED IN THE
WESTERLY FLOW PATTERN 05S WILL COMPLETE ETT. STORM INTENSITY IS
EXPECTED TO REMAIN IN THE WEAK TROPICAL STORM RANGE THROUGHOUT THE
UPCOMING PHASE TRANSITIONS AS FAVORABLY BAROCLINIC SUPPORT OFFSETS
THE NEGATIVE IMPACTS OF PASSAGE OVER COOLER WATER AND INCREASING
VERTICAL WIND SHEAR.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN EXCELLENT AGREEMENT THAT
05S WILL ROUND THE SUB-TROPICAL RIDGE AND PROGRESS DEEP INTO THE
MID-LATITUDE WESTERLIES BECOMING AN EXTRA-TROPICAL LOW.  RELIABLE
MODEL INTENSITY GUIDANCE IS IN SIMILARLY GOOD AGREEMENT THAT
INTENSITIES WILL GRADUALLY WEAKEN THROUGHOUT THE FORECAST PERIOD
THOUGH ANY SIGNIFICANT NEGATIVE ENVIRONMENTAL INFLUENCES WILL BE
BLUNTED BY THE AFOREMENTIONED FAVORABLY BAROCLINIC SUPPORT. FOR
THESE REASONS THE JTWC TRACK AND INTENSITY FORECAST IS PLACED WITH
HIGH CONFIDENCE.

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