WDPS31 PGTW 151500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (NINETEEN)   
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.4S 137.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 367 NM EAST OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED PROXYVIS SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM 
WITH DEEP CONVECTION INCREASING IN AREAL EXTENT, OBSCURING THE LOW-
LEVEL CIRCULATION CENTER (LLCC). HOWEVER, ANIMATED RADAR IMAGERY FROM 
THE GOVE AIRPORT RADAR DEPICTS A FAIRLY DEFINED LLCC JUST NORTHEAST 
OF GROOTE EYLANDT AIRPORT, WITH CONVECTIVE BANDING PRIMARILY OVER THE 
WESTERN SEMICIRCLE. THEREFORE, THERE IS HIGH CONFIDENCE IN THE 
INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS WITH 
MEDIUM CONFIDENCE BASED ON THE PGTW AND KNES DVORAK ESTIMATES AS WELL 
AS RECENT SURFACE OBSERVATIONS IN THE AREA. SURFACE OBSERVATIONS FROM 
GROOTE EYLANDT AIRPORT ARE UNIMPRESSIVE WITH WINDS LESS THAN 15 KNOTS 
AND SLP NEAR 999 MB. HOWEVER, SURFACE OBSERVATIONS FROM NGAYAWILI 
(12.0S 135.5E) REVEAL SUSTAINED WESTERLY WINDS AS HIGH AS 43 KNOTS 
(10-MINUTE AVERAGE) OVER THE PAST 12 HOURS. CAPE WESSEL (11.0S 
136.7E) INDICATES 30 TO 40 KNOT SUSTAINED WESTERLY WINDS OVER THE 
PAST 12 HOURS. ENVIRONMENTAL CONDITIONS ARE GRADUALLY IMPROVING WITH 
LOW TO MODERATE VERTICAL WIND SHEAR AND EXPANDING EQUATORWARD AND 
POLEWARD OUTFLOW. SST VALUES (30 TO 31 C) ARE CONDUCIVE FOR FURTHER 
DEVELOPMENT. 

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WEAK SUBTROPICAL RIDGE (STR) POSITIONED
TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   ADRM: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 19P IS FORECAST TO TRACK
GENERALLY SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE NORTH-SOUTH
ORIENTED STR POSITIONED TO THE EAST THROUGH TAU 48. TC 19P WILL
INTENSIFY QUICKLY AS IT TRACKS AWAY FROM LAND WITH A PEAK INTENSITY
OF 65 KNOTS EXPECTED FROM TAU 36 TO TAU 48. AFTER TAU 48, THE
SYSTEM WILL TRANSITION STEERING TO A SUBTROPICAL RIDGE POSITIONED
SOUTH OF THE SYSTEM AND WILL TURN WESTWARD, MAKING LANDFALL NEAR
TAU 72. RAPID WEAKENING WILL OCCUR AS THE SYSTEM TRACKS INLAND,
WITH DISSIPATION EXPECTED BY TAU 96.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, NUMERICAL MODEL
GUIDANCE IS FAIR AGREEMENT THROUGH THE FORECAST PERIOD, LENDING
MEDIUM OVERALL CONFIDENCE TO THE JTWC TRACK FORECAST. THE 150600Z
ECMWF AND GFS ENSEMBLES (EPS AND GEFS) ALSO SUPPORT THE JTWC TRACK
FORECAST. RELIABLE INTENSITY GUIDANCE SUPPORTS THE SHARP 
INTENSIFICATION TREND THROUGH TAU 36 AND ALSO THE RAPID WEAKENING
PHASE AFTER TAU 72 WITH MEDIUM OVERALL CONFIDENCE. ALTHOUGH THE
150600Z COAMPS-TC INTENSITY PROBABILITY GUIDANCE DOES NOT INDICATE
RAPID INTENSIFICATION, IT DOES SHOW 40 TO 60 PERCENT PROBABILITIES
FOR MODERATE INTENSIFICATION THROUGH TAU 36.    

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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