WDXS31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02S (BHEKI) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.6S 68.5E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 653 NM EAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION PERSISTING OVER THE SOUTHERN AND WESTERN PORTIONS OF A
LOW-LEVEL CIRCULATION EVIDENT IN 181637Z TROPICS PASS. THE INITIAL
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON MULTI-AGENCY
SATELLITE POSITION FIXES AND THE NOTED TROPICS IMAGERY. THE INITIAL
INTENSITY OF 75 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A
CONSENSUS OF SUBJECTIVE DVORAK AND AUTOMATED INTENSITY ESTIMATES
AND EXTRAPOLATION OF THE RECENT INTENSITY TREND. TROPICAL CYCLONE
(TC) 02S HAS STEADILY WEAKENED OVER THE PAST TWELVE HOURS UNDER THE
INFLUENCE OF INCREASING WESTERLY VERTICAL WIND SHEAR AND PASSAGE
OVER COOLER WATER.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
SOUTHEAST TRANSITIONING TO STR BUILDING TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T5.0 - 90 KTS
   FIMP: T4.5 - 77 KTS
   CIMSS SATCON: 60 KTS AT 181412Z
   CIMSS ADT: 59 KTS AT 181800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 25-26 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 02S WILL TRACK WESTWARD TO
WEST-SOUTHWESTWARD THROUGH THE FORECAST PERIOD AS DEVELOPING
SUBTROPICAL RIDGING TO THE SOUTH BECOMES THE PRIMARY STEERING
MECHANISM. STEADY WEAKENING IS ANTICIPATED AS THE SYSTEM PASSES
OVER UNFAVORABLE (25-26C) SEA SURFACE TEMPERATURES AND CONTENDS
WITH PERSISTENT MODERATE TO STRONG VERTICAL WIND SHEAR. ALTHOUGH
THE LOW-LEVEL CIRCULATION IS EXPECTED TO DECOUPLE FROM ACCOMPANYING
DEEP CONVECTION WITHIN THE NEXT DAY OR TWO, THE WIND FIELD WILL
TAKE A WHILE TO SUBSIDE LATER IN THE FORECAST PERIOD WITH
DISSIPATION BELOW THE WARNING THRESHOLD OF 35 KNOTS OCCURRING BY TAU
96. 

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, A POLEWARD OUTLIER
FROM THE PRIMARY MODEL GROUPING, NUMERICAL MODEL TRACK FORECAST
GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD. THE
JTWC FORECAST LIES VERY SLIGHTLY TO THE NORTH OF THE PREVIOUS
WARNING. GIVEN THE FAIRLY STRAIGHTFORWARD STEERING PATTERN THAT IS
DEVELOPING AND CONSISTENCY IN MODEL GUIDANCE OVER THE PAST SEVERAL
RUNS, CONFIDENCE IN THE TRACK FORECAST IS HIGH. NUMERICAL MODELS
ARE ALSO IN GOOD AGREEMENT REGARDING THE INTENSITY FORECAST TREND,
DEPICTING STEADY FOLLOWED BY SLOWER WEAKENING TO DISSIPATION. THERE
IS HIGH CONFIDENCE IN THE JTWC INTENSITY FORECAST. 

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