WDXS31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HORACIO) WARNING 
NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.0S 66.5E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 524 NM EAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 22S IS CURRENTLY UNDERGOING RAPID 
INTENSIFICATION (RI) UNDER HIGHLY FAVORABLE ENVIRONMENTAL CONDITIONS. 
AT 222100Z, ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTED A 
CONSOLIDATING SYSTEM LACKING A DISCERNIBLE EYE. BY 230000Z, EYE 
FORMATION WAS OBSERVED, AND OVER THE LAST TWO HOURS, THE FEATURE HAS 
RAPIDLY CLEARED AND WARMED, REVEALING AN APPROXIMATELY 20NM WIDE EYE 
WITH A PEAK TEMPERATURE OF +12C. A 230110Z RCM-3 SAR PASS REVEALED A 
MEAN INTENSITY OF 80 KNOTS AND A PEAK INTENSITY OF 87 KNOTS, 
VALIDATING THE COMMENCEMENT OF RI PRIOR TO THE COLLECTION TIME. IN 
CONJUNCTION WITH A 230437Z ASCAT PASS, THE WIND FIELD IS ASSESSED 
WITH HIGH CONFIDENCE AS EXTREMELY COMPACT, WITH THE MAXIMUM EXTENT OF 
GALE-FORCE WINDS CONFINED WITHIN 100NM. A 230622Z GMI PASS DEPICTED A 
VERTICALLY ALIGNED MICROWAVE EYE SURROUNDED BY DEEP CONVECTION IN ALL 
QUADRANTS EXCLUDING THE SOUTHEASTERN SECTOR, WHERE THE EYEWALL 
DISPLAYED DIMINISHED CONVECTIVE DEPTH. THE INITIAL POSITION IS 
ASSESSED WITH HIGH CONFIDENCE BASED ON THE LOW-LEVEL CIRCULATION 
CENTER (LLCC) EVIDENT IN THE GMI 37GHZ IMAGE. THE INITIAL INTENSITY
IS ASSESSED WITH MEDIUM CONFIDENCE, BIASED HIGHER THAN AGENCY 
SUBJECTIVE DVORAK ESTIMATES AND THE BULK OF OBJECTIVE GUIDANCE IN 
LIGHT OF THE EARLIER SAR PASS AND THE KNOWN TENDENCY FOR DVORAK-BASED 
TECHNIQUES TO UNDERESTIMATE THE INTENSITY OF COMPACT SYSTEMS. 
ENVIRONMENTAL FAVORABILITY HAS PEAKED, CHARACTERIZED BY LOW VWS, WARM 
SSTS, AND VIGOROUS RADIAL OUTFLOW.

INITIAL WIND RADII BASIS: SAR AND SCATTEROMETER DATA. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T5.0 - 90 KTS
   FIMP: T5.0 - 90 KTS
   CIMSS SATCON: 81 KTS AT 230330Z
   CIMSS ADT: 102 KTS AT 230600Z
   CIMSS AIDT: 98 KTS AT 230600Z
   CIMSS D-MINT: 87 KTS AT 230622Z
   CIMSS D-PRINT: 82 KTS AT 230600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: COMPACT NATURE THE SYSTEM. 

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 22S WILL CONTINUE TO TRANSIT ALONG A GRADUAL 
RECURVING ARC TO THE SOUTH OVER THE NEXT 12 TO 24 HOURS AS IT 
APPROACHES THE STR AXIS. THE SYSTEM IS FORECAST TO ROUND THE WESTERN 
PERIPHERY OF THE RIDGE NEAR TAU 24, THEN TRACK SOUTHEASTWARD ALONG 
THE SOUTHWESTERN FLANK OF THE RIDGE THROUGH TAU 72. AT TAU 72, AN 
UPPER-LEVEL TROUGH IS FORECAST TO PASS TO THE SOUTH, ALLOWING A LOW- 
TO MID-LEVEL RIDGE TO BUILD BEHIND THE TROUGH. THIS WILL POSITION TC 
22S ON THE NORTHERN FLANK OF THE RIDGE, STEERING THE SYSTEM TOWARDS 
THE WEST-SOUTHWEST. BY TAU 96, THE TRANSITORY RIDGE TRANSLATES 
QUICKLY EASTWARD, CAUSING TC 22S TO ROUND THE AXIS AND TURN SOUTHWARD 
THROUGH THE REMAINDER OF THE FORECAST PERIOD. TC 22S HAS RAPIDLY 
INTENSIFIED OVER THE PAST 12 HOURS COINCIDENT WITH THE ACHIEVEMENT OF 
A VERTICALLY ALIGNED VORTEX. A FINITE WINDOW OF OPPORTUNITY FOR 
ADDITIONAL RI PERSISTS OVER THE NEXT 12 HOURS BEFORE CONDITIONS ARE 
PROJECTED TO QUICKLY DETERIORATE. THEREFORE, TC 22S IS FORECAST TO 
REACH A PEAK INTENSITY OF 115-120 KNOTS BY TAU 12, AFTER WHICH 
INCREASING VWS WILL INITIATE VORTEX DECOUPLING. WEAKENING WILL BE 
GRADUAL THROUGH TAU 36 AS THE VORTEX DECOUPLES IN A TOP-DOWN MANNER. 
THE ONSET OF RAPID DECAY IS EXPECTED BY TAU 48 AS PRONOUNCED MID-
LEVEL DRY AIR INTRUSION ENGULFS THE CORE, LEAVING A SHALLOW, WARM-
CORE RESIDUAL VORTEX MOVING OVER MARGINAL (LESS THAN 26C) WATERS. BY 
TAU 96, THE SYSTEM WILL BEGIN SUBTROPICAL TRANSITION (STT), WITH 
COMPLETION EXPECTED BY THE END OFTHE PERIOD. 

MODEL DISCUSSION: MODEL GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU
72, WITH MINIMAL CROSS- OR ALONG-TRACK UNCERTAINTY ACROSS THE FULL
GUIDANCE SUITE. AT TAU 72, A BIFURCATION OCCURS BETWEEN THE GFS, 
GEFS, AND NAVGEM, WHICH INITIATE A WEST-SOUTHWESTWARD TURN, AND THE 
ECMWF AND ARTIFICIAL INTELLIGENCE (AI) MODELS, WHICH MAINTAIN A 
SOUTHEASTWARD TRAJECTORY. CONSEQUENTLY, CROSS-TRACK SPREAD INCREASES 
TO 230NM AT TAU 72. BY TAU 96, CONSENSUS IS REACHED REGARDING A 
SOUTHWESTWARD TURN, FOLLOWED BY A SOUTHERLY TRACK AFTER TAU 96; 
HOWEVER, THE UNCERTAINTY INHERITED FROM TAU 72 PERSISTS, WITH SPREAD 
EXPANDING TO 310NM BY TAU 120. THE JTWC FORECAST IS PLACED NEAR THE 
ECMWF DETERMINISTIC TRACKER WITH HIGH CONFIDENCE THROUGH TAU 72 AND
MEDIUM CONFIDENCE THEREAFTER. INTENSITY GUIDANCE DIVERGES, WITH COTC 
AND HWRF INDICATING THE SYSTEM HAS REACHED ITS PEAK, WHILE HAFS-A, 
CTCX, AND SHIPS GUIDANCE SUPPORT ADDITIONAL INTENSIFICATION UP TO
105-115 KNOTS BY TAU 12. FURTHERMORE, THE DTOP AND RIDE RI AIDS 
REMAIN TRIGGERED, SUPPORTING A PEAK INTENSITY NEAR 120 KNOTS. THE 
JTWC FORECAST IS CONSISTENT WITH THE RIDE AND CTCX TRENDS THROUGH TAU 
12, THEN GENERALLY FOLLOWS SHIPS OUTPUT THROUGH TAU 120.
FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH
   INTENSITY 72-120 HR: MEDIUM//
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