WDXS31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02S (TERATAI) WARNING 
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1S 105.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 151 NM SOUTH OF CHRISTMAS ISLAND,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
PARTIALLY-EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC)
WITH A SYMMETRIC, PERSISTENT CLUSTER OF DEEP CONVECTION SHEARED
OVER THE WESTERN SEMICIRCLE DUE TO MODERATE EASTERLY VERTICAL WIND
SHEAR (VWS). A 080553Z ATMS 88GHZ MICROWAVE IMAGE INDICATES THE
LLCC IS NOT WELL-ORGANIZED AND HAS MAINTAINED A LINEAR BAND OF DEEP
CONVECTION STREAMING WESTWARD FROM THE CENTER. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI. INITIAL INTENSITY
OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON RECENT ASCAT
DATA, AND REMAINS HEDGED ABOVE THE PGTW CURRENT INTENSITY ESTIMATE.
THE 080540-0640Z ADT ESTIMATES HAVE RANGED FROM 37 TO 39 KNOTS
BASED ON AN IRREGULAR CDO SCENE TYPE. UPPER-LEVEL CONDITIONS REMAIN
MARGINALLY FAVORABLE WITH MODERATE POLEWARD OUTFLOW, ENHANCED BY A
BROAD UPPER-LEVEL TROUGH APPROACHING FROM THE WEST, WHICH IS
OFFSETTING THE MODERATE VWS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A STR ENTRENCHED
TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   CIMSS ADT: 37 KTS AT 080540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 02S IS EXPECTED TO TRACK WEST-SOUTHWESTWARD
ALONG THE NORTHWEST PERIPHERY OF THE STR THROUGH THE FORECAST
PERIOD. ALTHOUGH SLIGHT INTENSIFICATION IS POSSIBLE IN THE NEXT 12
HOURS, THE SYSTEM IS FORECAST TO MAINTAIN INTENSITY AT 35 KNOTS
THROUGH TAU 36 THEN TO DISSIPATE BY TAU 48 DUE TO AN UNFAVORABLE
UPPER-LEVEL ENVIRONMENT CHARACTERIZED BY CONVERGENCE ALOFT
(ASSOCIATED WITH THE AFOREMENTIONED TROUGH) AND DRY AIR
ENTRAINMENT.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, WHICH IS THE SOLE
OUTLIER ON THE POLEWARD SIDE OF THE AIDS ENVELOPE (KNOWN ERROR IN 
DRIVING THE SYSTEM INTO THE STR), NUMERICAL TRACK GUIDANCE REMAINS 
IN CLOSE AGREEMENT THROUGH TAU 48 WITH A 60NM SPREAD IN SOLUTIONS AT 
TAU 48. BOTH THE ECMWF ENSEMBLE (EPS) AND THE GFS ENSEMBLE (GEFS) 
INDICATE A TIGHT GROUPING OF MEMBERS WITH THE BULK OF THE SOLUTIONS 
SUPPORTING A GRADUAL WEAKENING TO 20-30 KNOTS. RELIABLE INTENSITY 
GUIDANCE ALSO SUPPORTS THE INTENSITY FORECAST PHILOSOPHY ALTHOUGH 
HWRF DOES PEAK AT 38 KNOTS BEFORE WEAKENING OCCURS AFTER TAU 12. THE 
JTWC FORECAST IS CLOSELY ALIGNED WITH THE JTWC INTENSITY CONSENSUS 
(ICNW).   

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