WDXS31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02S (BHEKI) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.8S 74.4E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 360 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
INCREASINGLY ORGANIZED DEEP CONVECTION DEVELOPING OVER A LOW-LEVEL
CIRCULATION CENTER EVIDENT IN 151310Z SSMIS IMAGERY. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON TIGHTLY CLUSTERED
SATELLITE POSITION FIXES FROM PGTW, KNES, FMEE, AND DEMS. THE
INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A CONSENSUS OF SUBJECTIVE DVORAK AND AUTOMATED INTENSITY
ESTIMATES RANGING FROM 50 KTS (CIMSS AIDT) TO 77 KTS (KNES DVORAK).
TROPICAL CYCLONE (TC) 02S HAS MAINTAINED INTENSITY BUT CONVECTIVE
BANDING STRUCTURE HAS SHOWN SIGNS OF IMPROVEMENT AS THE SYSTEM
MOVES POLEWARD INTO A ZONE OF LOWER NORTHEASTERLY VERTICAL WIND
SHEAR.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.0 - 65 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS SATCON: 58 KTS AT 151629Z
   CIMSS ADT: 59 KTS AT 151800Z
   CIMSS AIDT: 50 KTS AT 151700Z
   CIMSS D-PRINT: 65 KTS AT 151800Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE INTENSIFICATION RATE, TIMING OF
PEAK INTENSITY, AND SUBSEQUENT WEAKENING HAVE SHIFTED TO THE LEFT
(SOONER) THAN PREVIOUSLY FORECAST. OVERALL, THE INTENSITY CHANGE
CURVE IS SIMILAR TO THE PREVIOUS FORECAST ASIDE FROM THE TIMING.

FORECAST DISCUSSION: TC 02S WILL TRACK GENERALLY WEST-SOUTHWESTWARD
OVER THE NEXT 72 HOURS UNDER THE CONTINUED INFLUENCE OF THE STR TO
THE SOUTHEAST. HOWEVER, BY TAU 72, VERTICAL WIND SHEAR IS EXPECTED
TO INCREASE SIGNIFICANTLY AS THE SYSTEM ENCOUNTERS STRONG WESTERLY
FLOW ALOFT. INCREASING SHEAR, AND PASSAGE OVER MARGINALLY SUPPORTIVE
SEA SURFACE TEMPERATURES (26-27C) WILL INDUCE WEAKENING THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE STEERING LEVEL WILL ALSO DROP
AS THE SYSTEM WEAKENS. A LOW- TO MID-LEVEL RIDGE TO THE SOUTH IS
EXPECTED TO BECOME THE PRIMARY STEERING INFLUENCE, TURNING THE
SYSTEM TOWARD A GENERALLY WESTWARD TRACK AFTER TAU 72 AND THROUGH
THE REMAINDER OF THE FORECAST PERIOD. TC 02S WILL CONTEND WITH
VERTICAL WIND SHEAR, MID- TO UPPER-LEVEL DRY AIR ENTRAINMENT AND
PASSAGE OVER COOLER WATER (25-26C) DURING THE EXTENDED FORECAST
PERIOD, RESULTING IN A STEADY WEAKENING TREND.

MODEL DISCUSSION: NUMERICAL MODEL FORECAST GUIDANCE IS IN VERY GOOD
AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO. TRACK FORECASTS
ARE TIGHTLY PACKED THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THAT
PORTION OF THE TRACK FORECAST. BEYOND TAU 72, MODEL TRACKER SPREAD
INCREASES, WITH THE UKMET-BASED MODELS SHOWING A SLOWER TRACK TO
THE WEST-NORTHWEST, NCEP MODELS INDICATING A SLIGHTLY FASTER
WESTWARD TRACK, AND THE NAVGEM AND ECMWF-BASED MODELS INDICATING A
TRACK TO THE WEST-SOUTHWEST. THE CURRENT EXTENDED TRACK FORECAST IS
CONSISTENT WITH BOTH THE CONSENSUS TRACK, WHICH LIES IN THE MIDDLE OF
THE EVENLY SPREAD DISTRIBUTION, AND THE PREVIOUS JTWC FORECAST WITH 
MEDIUM CONFIDENCE IN THE EXTENDED PERIOD. CONSENSUS INTENSITY
GUIDANCE IS IN GOOD AGREEMENT REGARDING THE INTENSITY TREND, BUT
HAFS DEPICTS THE POTENTIAL FOR MORE PRONOUNCED INTENSIFICATION UP
TO OR EXCEEDING 100 KTS BY TAU 48, WHICH IS POSSIBLE GIVEN THE
SHORT WINDOW OF SUPPORTIVE ENVIRONMENTAL CONDITIONS THAT HAS
DEVELOPED. THERE IS MEDIUM CONFIDENCE IN THE INTENSITY FORECAST
GIVEN THE NEAR TO MEDIUM-TERM FORECAST UNCERTAINTIES.

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