WDXS31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HORACIO) WARNING 
NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.8S 69.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 950 NM SOUTHEAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), EXHIBITING ACCELERATED
STRUCTURAL DISORGANIZATION. MULTI-LAYER ADVECTABLE TOTAL PRECIPITABLE 
WATER IMAGERY CORROBORATES MESOSCALE MODEL FIELDS INDICATING A DEEP
SUBSIDENT LAYER OF DRY AIR OVERLYING THE SYSTEM. GIVEN SEA SURFACE
TEMPERATURES (SST) BELOW 24C AND THE RESULTANT DEFICIT IN 
THERMODYNAMIC ENERGY, CONVECTIVE REIGNITION IS UNLIKELY. ANIMATED 
WATER VAPOR IMAGERY AS WELL AS DERIVED MOTION VECTOR WINDS DEPICT 
VERY STRONG (OVER 45 KNOTS) OF NORTHWESTERLY SHEAR IMPACTING THE 
SYSTEM. THE SYSTEM IS CURRENTLY POSITIONED NEAR THE AXIS OF A 
SUBTROPICAL JET STREAK ON THE EASTERN PERIPHERY OF A DEEP UPPER-LEVEL 
LOW. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON 
THE EXPOSED LLCC IN THE MSI. A 260339Z ASCAT-B PASS OBSERVED WINDS OF 
50-55 KNOTS WITHIN THE WESTERN QUADRANT, NOTABLY EXCEEDING SUBJECTIVE 
AND AUTOMATED INTENSITY ESTIMATES. INITIAL INTENSITY IS ASSESSED WITH 
HIGH CONFIDENCE, WEIGHTED HEAVILY TOWARD SCATTEROMETRY DATA. THE 
ENVIRONMENT REMAINS HOSTILE DUE TO EXTREME VWS, MID-LEVEL DRY AIR 
ENTRAINMENT, AND SUB-MARGINAL SSTS LESS THAN 24C.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: TC 22S IS UNDERGOING A STEERING 
TRANSITION, SHIFTING FROM THE INFLUENCE OF THE SUBTROPICAL RIDGE 
(STR) TO THE WEST TOWARD THE NORTHERN PERIPHERY OF A TRANSITORY LOW-
TO-MID-LEVEL ANTICYCLONE TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 25 KTS AT 260500Z
   CIMSS AIDT: 36 KTS AT 260500Z
   CIMSS D-MINT: 36 KTS AT 260127Z
   CIMSS D-PRINT: 30 KTS AT 260600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30+ KTS
   SST: 23-24 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: SIGNIFICANT MID-LEVEL DRY AIR FIRMLY ENTRENCHED
OVER TOP OF THE SYSTEM. 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: FORECAST PERIOD TRUNCATED TO 24 HOURS.

FORECAST DISCUSSION: TC 22S IS RAPIDLY DECELERATING AS IT ENCOUNTERS
A TRANSITORY RIDGE TO THE SOUTH. WITHIN THE NEXT 12 HOURS, THE SYSTEM
WILL PIVOT WEST-SOUTHWESTWARD ALONG THE NORTHERN PERIPHERY OF THIS 
RIDGE. AS THE RIDGE PROPAGATES EASTWARD OVER THE 24-36 HOUR WINDOW,
TC 22S WILL MODIFY ITS TRACK SOUTHWESTWARD, EVENTUALLY TURNING SOUTH-
SOUTHEASTWARD AS IT ROUNDS THE WESTERN FLANK OF THE ANTICYCLONE.
DURING THIS WESTWARD TURN, THE SYSTEM WILL INCREASINGLY INTERACT WITH 
THE SUBTROPICAL JET ASSOCIATED WITH THE APPROACHING UPPER-LEVEL LOW. 
SUSTAINED NORTHWESTERLY SHEAR AND SUBSIDENCE WILL CONTINUE TO 
SUPPRESS CONVECTION. BY TAU 24, THE REMNANTS OF TC 22S WILL BE 
POSITIONED BENEATH THE UPPER-LEVEL COLD CORE, SIGNALING THE COMPLETION 
OF SUBTROPICAL TRANSITION. STEADY WEAKENING IS ANTICIPATED THROUGHOUT 
THE REMAINDER OF THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN STRONG
AGREEMENT, ALL MEMBERS OF THE CONSENSUS PACKAGE SUPPORTING THE JTWC
FORECAST TRACK. INTENSITY GUIDANCE IS ALSO IN STRONG AGREEMENT,
WITH ALL MEMBERS OF THE CONSENSUS INDICATING STEADY WEAKENING
THROUGH THE FORECAST PERIOD. CONFIDENCE IN BOTH TRACK AND INTENSITY
REMAINS HIGH. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
NNNN