WDPS31 PGTW 160900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (MEGAN) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 14.5S 137.6E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 409 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 06 KTS SIGNIFICANT WAVE HEIGHT: 20 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL CYCLONE (TC) 19P (MEGAN) SHOWING DEEP, PERSISTENT CENTRALIZED CONVECTION MOSTLY OBSCURING THE ASSESSED LOW-LEVEL CIRCULATION CENTER (LLCC). TRANSVERSE BANDS ARE OBSERVED ALONG THE NORTHERN PERIPHERY OF THE CIRCULATION WITH CIRRUS FILAMENTS FLOWING EQUATORWARD ALOFT. SPIRAL BANDS OF DEEP CONVECTION FILL OUT THE WESTERN SEMICIRCLE AND SHALLOW BANDING IS OBSERVABLE THROUGHOUT THE EASTERN SEMICIRCLE WRAPPING INTO THE LLCC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON SURFACE OBSERVATIONS AND A 160600Z HIMAWARI-9 VISIBLE SATELLITE IMAGE. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON SURFACE OBSERVATIONS, PERSISTENCE OF A 160022Z METOP-B SCATTEROMETRY IMAGE, AND THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A MID-LEVEL NEAR EQUATORIAL RIDGE (NER) TO THE EAST-NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS KNES: T3.5 - 55 KTS CIMSS SATCON: 51 KTS AT 160437Z CIMSS ADT: 55 KTS AT 160530Z CIMSS AIDT: 44 KTS AT 160730Z CIMSS DPRINT: 44 KTS AT 160600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE EQUATORWARD 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 19P (MEGAN) IS FORECAST TO TRACK SOUTHWARD (TAU 00 TO TAU 12) TO SOUTH-SOUTHWESTWARD (TAU 12 TO TAU 36) FOLLOWING THE STEERING INFLUENCE OF AN EXTENSION OF A NEAR-EQUATORIAL RIDGE TO THE EAST-NORTHEAST. ALONG-TRACK, A FAVORABLE ENVIRONMENT HAVING LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), VERY WARM (30-31 C) SEA SURFACE TEMPERATURES, A MOIST MID LEVEL (RELATIVE HUMIDITY NEAR 70 PCT), OFFSET BY LOW TO MODERATE DIVERGENCE ALOFT. OUTFLOW CONDITIONS ALOFT ARE FORECAST TO BECOME WEAKER FROM TAU 00 TO TAU 36, WHICH IS THE MAJOR RESTRAINT ON THE SYSTEM OVER THIS INTERVAL. HOWEVER, WITH ALL OTHER ENVIRONMENTAL FACTORS ASSESSED AS FAVORABLE, THE SYSTEM IS EXPECTED TO INTENSIFY TO NEAR 70 KTS BY TAU 24, WITH A PEAK INTENSITY LIKELY TO BE OBSERVED BETWEEN TAU 24 AND TAU 36. LANDFALL IS ANTICIPATED TO OCCUR BETWEEN TAU 36 AND TAU 48 ALONG THE SOUTHERN COAST OF THE GULF OF CARPENTARIA. DISSIPATION IS ANTICIPATED TO OCCUR PRIOR TO TAU 96 AS THE SYSTEM MOVES INLAND OVER NORTHERN AUSTRALIA. MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT REGARDING TRACK, WITH ALL JTWC CONSENSUS MEMBERS SUGGESTING A SOUTHWARD COMPONENT FROM TAU 00 TO TAU 48. AT TAU 48, ALL MEMBERS THEN TRACK THE SYSTEM WEST-SOUTHWESTWARD TO WESTWARD THROUGH TAU 96. A CROSS-TRACK SPREAD OF 96NM IS PRESENT BETWEEN THE ECMWF ENSEMBLE MEAN AND GALWEM BY TAU 48, LEAVING SOME UNCERTAINTY AS TO WHERE ALONG THE SOUTHERN GULF OF CARPENTARIA THE SYSTEM WILL TRACK ASHORE. INTENSITY GUIDANCE INCLUDES INDICATION THAT RAPID INTENSIFICATION MAY BE OBSERVED IN THE NEXT 24 HOURS. THOUGH, THE PROBABILITY OF OCCURRENCE ASSOCIATED WITH THESE AIDS IS NEAR 30 TO 40 PERCENT. INTENSITY CONSENSUS MEMBERS ARE UNIFORM IN NATURE, INDICATING A RISE IN INTENSITY TO A PEAK PRIOR TO TAU 36, FOLLOWED BY A WEAKENING TREND AS THE SYSTEM TRACKS SOUTH OVER LAND. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72 - 96 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72 - 96 HR: MEDIUM// NNNN