WDXS31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 25S (KARIM) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.1S 90.3E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 390 NM WEST-NORTHWEST OF CHRISTMAS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A MEDIUM
SIZED SYSTEM WITH FLARING DEEP CENTRAL CONVECTION WITH EQUALLY DEEP
RAIN BANDS WRAPPING IN MOSTLY FROM THE SOUTH. STRONG NORTHERLY
UPPER LEVEL WINDS ARE ENHANCING ROBUST POLEWARD OUTFLOW AS
EVIDENCED BY SOUTHWARD STRIATIONS IN THE CIRRUS CANOPY. HOWEVER,
THE SAME STRONG WINDS ARE ALSO CAUSING PRESSURE AND SUBSIDENCE
ALONG THE NORTHERN EDGES. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON LOW LEVEL CIRCULATION FEATURES IN THE
071317Z GMI AND 071529Z AMSU-B MICROWAVE IMAGES. THE INITIAL
INTENSITY OF 45KTS PLACED WITH MEDIUM CONFIDENCE BASED ON THE PGTW
AND APRF DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A WEAK
NEAR-EQUATORIAL RIDGE TO THE EAST.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS SATCON: 53 KTS AT 071530Z
   CIMSS ADT: 51 KTS AT 071515Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   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 25S WILL CONTINUE ON ITS CURRENT TRACK
UNDER THE NER. AFTER TAU 72, A BUILDING SUBTROPICAL RIDGE FROM THE
SOUTHWEST WILL ASSUME STEERING AND FORCE A COUNTER-CLOCKWISE
LOOPING MOTION. THE MARGINAL ENVIRONMENT WILL PROMOTE A MODEST
INTENSIFICATION TO A PEAK OF 60KTS AT TAUS 36-48. AFTERWARD,
INCREASING VWS, THEN COOLING SST WILL GRADUALLY ERODE THE SYSTEM TO
DISSIPATION BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH THE TRACK FORECAST. HOWEVER, GIVEN THE UNCERTAINTY IN THE
STORM MOTION DURING THE TRANSITION IN THE STEERING MECHANISM AFTER
TAU 72, THERE IS ONLY MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST
THAT IS LAID CLOSE TO THE CONSENSUS.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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