WDXS31 PGTW 222100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HORACIO) WARNING 
NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.8S 68.2E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 634 NM EAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 22S (HORACIO) WITH SIGNIFICANTLY IMPROVED VORTEX ALIGNMENT
AND CENTRALIZED CONVECTION. CIRRUS FILAMENTS CAN BE SEEN EXPANDING
OUTWARD FROM THE SYSTEM IN ALL DIRECTIONS, INDICATIVE OF STRONG
OUTFLOW CHANNELS. THE EASTERLY SHEAR APPEARS TO HAVE MARKEDLY
LESSENED OVER THE PAST 12 HOURS, WITH EASTWARD OUTFLOW MUCH LESS
RESTRICTED. A 221458Z F16 SSMIS 37 GHZ MICROWAVE IMAGE SHOWED THE
COMPACT INNER-CORE OF THE SYSTEM WITH A MICROWAVE EYE FEATURE THAT
HAS A SLIGHT WEAKNESS WITHIN THE NORTHEASTERN QUADRANT. A 221400Z
RCM-3 SAR IMAGE REVEALED THAT THE STRONGEST WINDS ARE CONFINED TO
THE SOUTHERN SEMICIRCLE. THE VMAX MEASUREMENT OF THE SAR PASS WAS
68 KTS AND WAS LOCATED DIRECTLY TO THE SOUTH OF THE CENTER. THE
INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE AGREEMENT OF T3.5 DVORAK FIXES FROM ALL AGENCIES, SUPPORTED
BY THE SAR IMAGE (WITH A REDUCTION FROM THE VMAX DUE TO THE KNOWN
HIGH BIAS ASSOCIATED WITH THE RCM SENSORS). CIMSS ESTIMATES, WITH
THE EXCEPTION OF DMINT, ARE ANALYZED TO BE TOO LOW, LIKELY DUE TO
THE SMALLER SIZE OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE ANIMATED EIR IMAGERY AND EXTRAPOLATION
FROM THE AFOREMENTIONED SSMIS MICROWAVE IMAGE. ENVIRONMENTAL
ANALYSIS INDICATES THAT 22S IS IN A FAVORABLE ENVIRONMENT
CHARACTERIZED BY ROBUST OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL
WIND SHEAR, AND WARM (27-28 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: 221400Z RCM-3 SAR DATA

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   FMEE: T3.5 - 55 KTS
   FIMP: T3.5 - 55 KTS
   CIMSS SATCON: 46 KTS AT 221630Z
   CIMSS ADT: 45 KTS AT 221800Z
   CIMSS AIDT: 38 KTS AT 221800Z
   CIMSS D-MINT: 53 KTS AT 221459Z
   CIMSS D-PRINT: 46 KTS AT 221800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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 22S IS FORECAST TO TRACK SOUTHWESTWARD,
ALONG THE NORTHWESTERN PERIPHERY OF THE STR THROUGH TAU 36. NEAR
TAU 36, THE SYSTEM WILL TURN SOUTHWARD AND THEN SOUTH-SOUTHEASTWARD
AS IT ATTEMPTS TO ROUND THE RIDGE AXIS. NEAR TAU 72, A SMALL STR IS
EXPECTED TO BRIEFLY BUILD TO THE SOUTH OF THE SYSTEM, CAUSING THE
POLEWARD PROGRESSION TO BE OBSTRUCTED. THE INTERACTION WITH THE
SMALL STR WILL CAUSE 22S TO BE DEFLECTED TO THE SOUTHWEST THROUGH
TAU 120 BEFORE TURNING BACK TO THE SOUTHEAST. EXTRATROPICAL
TRANSITION IS FORECAST TO BEGIN NEAR TAU 96 WITH COMPLETION AROUND
TAU 120 AS THE SYSTEM ENTERS COLD (SUB 22 C) WATERS AND TRACKS
POLEWARD OF A STRONG UPPER-LEVEL LOW, WHICH WILL INDUCE
BAROCLINICITY. REGARDING INTENSITY, 22S IS FORECAST TO RAPIDLY
INTENSIFY THROUGH TAU 36 TO A PEAK OF AROUND 100 KTS IN RESPONSE TO
THE LOW SHEAR AND ROBUST OUTFLOW. THE POLEWARD OUTFLOW CHANNEL IN
PARTICULAR IS EXPECTED TO FURTHER IMPROVE OVER THE NEXT 24 HOURS,
SUPPORTING THE RAPID INTENSIFICATION (RI). AFTER TAU 36,
NORTHWESTERLY SHEAR IS EXPECTED TO QUICKLY INCREASE, CAUSING 22S TO
BEGIN WEAKENING. THE SYSTEM IS FORECAST TO PASS THE 26 DEGREE
ISOTHERM AROUND TAU 72 WITH SEA SURFACE TEMPERATURES FURTHER
DROPPING THEREAFTER, WHICH WILL ALSO AID IN WEAKENING THE VORTEX
THROUGH THE REMAINDER OF THE FORECAST PERIOD. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT THROUGHOUT TAU 72, WITH THE EXCEPTION OF NAVGEM WHICH
TRACKS THE VORTEX SIGNIFICANTLY FURTHER WEST THAN THE REMAINDER OF
GUIDANCE. DISCOUNTING NAVGEM, THERE IS A MERE 35 NM CROSS-TRACK
SPREAD AT TAU 72. AFTER TAU 72, MODELS BEGIN TO SLIGHTLY DIVERGE
DUE TO DIFFERING INTERACTIONS WITH THE SMALL RIDGE THAT BUILDS TO
THE SOUTH OF THE VORTEX. CROSS-TRACK SPREAD THEN INCREASES TO
AROUND 200 NM AT TAU 120 WITH THE GFS ENSEMBLE MEAN BEING THE
WESTERN MOST MODEL (BESIDES NAVGEM) AND THE ECMWF AIFS BEING THE
EASTERNMOST MODEL. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
ADJUSTED MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. RELIABLE
INTENSITY GUIDANCE AGREES ON RAPID OR NEAR-RAPID INTENSIFICATION
THROUGH TAU 36 WITH MULTIPLE RI AIDS TRIGGERING THIS MODEL RUN. RI
AND MESOSCALE MODELS HAVE A PEAK INTENSITY RANGING FROM 90-110 KTS.
THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE CONSENSUS
THROUGH TAU 24, AND THEN ABOUT 10 KTS HIGHER AT TAU 36, CLOSER TO
THE RI AIDS. MODELS THEN AGREE ON WEAKENING THROUGH THE REMAINDER
OF THE FORECAST PERIOD, AND THE JTWC FORECAST FOLLOWS CLOSELY TO
THE CONSENSUS MEAN THROUGH TAU 120. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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