WDXS32 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06S (ANGGREK) WARNING 
NR 031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 29.1S 72.8E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 1002 NM SOUTHEAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT TROPICAL
CYCLONE (TC) 06S (ANGGREK) IS RAPIDLY SUCCUMBING TO STRONG
NORTHWESTERLY VERTICAL WIND SHEAR (VWS). A DEARTH OF RECENT
MICROWAVE IMAGERY HAS MADE ANALYSIS SOMEWHAT CHALLENGING, BUT THE
MSI CLEARLY SHOWS THE CONVECTION HAS BEEN COMPLETELY DISPLACED
AWAY FROM THE NOW EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). THE
INITIAL POSITION IS THUS SET WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY IS SET AT 100 KNOTS, WITH MEDIUM CONFIDENCE. THE
INTENSITY IS HEDGED ABOVE THE MAJORITY OF THE OBJECTIVE FIX
ESTIMATES BUT REMAINS CONSISTENT WITH THE DVORAK CURRENT INTENSITY
(CI) ESTIMATES FROM MULTIPLE AGENCIES NOTED BELOW. THE PAST 24
HOURS WORTH OF BEST TRACK INTENSITIES HAVE BEEN REANALYZED UPWARDS
BASED ON MULTIPLE SYNTHETIC APERTURE RADAR (SAR), SMAP, AND
ULTRA-HIGH RESOLUTION (UHR) ASCAT PASSES WHICH INDICATED MAXIMUM
WINDS ROUGHLY 10-15 KNOTS HIGHER THAN THE OBJECTIVE AND SUBJECTIVE
FIX ESTIMATES. HOWEVER, THE PARTY IS NOW OVER AND THE SYSTEM IS IN
RAPID DECLINE AS VWS IS NOW OVER 30 KNOTS, SSTS ARE AT OR BELOW 26C
AND DRY AIR IS RAPIDLY MOVING IN FROM THE WEST. THE SYSTEM IS
RACING SOUTHEAST ALONG THE STRONG GRADIENT BETWEEN THE STR TO THE
EAST AND A FRONTAL BOUNDARY ABOUT 100NM TO THE SOUTH.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T5.0 - 90 KTS
   CIMSS ADT: 79 KTS AT 300600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30+ KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: VERY DRY AIR RAPIDLY ENCROACHING FROM THE WEST. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 06S IS FORECAST TO CONTINUE TO ACCELERATE
TOWARDS THE SOUTHEAST ALONG THE TIGHT GRADIENT BETWEEN THE STR TO
THE EAST-NORTHEAST AND A STRONG FRONTAL BOUNDARY LURKING ABOUT
100NM SOUTH OF THE SYSTEM. TC 06S IS ALREADY BEING SHEARED APART BY
35 KNOTS OF NORTHWESTERLY SHEAR AND BEING ENGULFED BY DRY MID-LEVEL
AIR BEING USHERED IN ALONG THE SHEAR VECTOR. MODEL-BASED PHASE SPACE 
DIAGRAMS DEPICT A RAPID EXTRA-TROPICAL TRANSITION (ETT), STARTING 
WITHIN THE NEXT 12 HOURS AND COMPLETING WITHIN THE NEXT 24-36 HOURS AS 
THE SYSTEM EMBEDS ITSELF INTO THE FRONTAL BOUNDARY, MOVES UNDER AN 
EXTREMELY STRONG UPPER-LEVEL JET MAX AND MOVES OVER RELATIVELY COLD 
WATERS LESS THAN 21C. WHILE THE SYSTEM UNDERGOES ETT, IT WILL RAPIDLY 
WEAKEN, BUT IS EXPECTED TO COMPLETE TRANSITION AS A STORM-FORCE LOW 
PRESSURE SYSTEM. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT ON THE SOUTHEASTWARD TRACK, THOUGH AS EXPECTED,
ALONG-TRACK SPREAD INCREASES SHARPLY AS THE SYSTEM UNDERGOES ETT.
THE JTWC TRACK IS CONSISTENT WITH THE CONSENSUS MEAN WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, WITH ALL
MODELS SHOWING A SHARP AND RAPID WEAKENING THROUGH THE END OF THE
FORECAST. THE JTWC FORECAST IS CONSISTENT WITH, THOUGH SLIGHTLY
ABOVE, THE CONSENSUS MEAN WITH HIGH CONFIDENCE. 

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