Western Pacific: JTWC are issuing warnings on a cyclonic trio, 04/15utc updates

04/15UTC. JTWC ARE ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 13W, 14W AND 15W.

TS 13W(LUPIT). WARNING 8 ISSUED AT 04/15UTC.THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: UNDER THE STEERING INFLUENCE OF THE NEAR EQUATORIAL RIDGE, TS LUPIT WILL CONTINUE ON A NORTHEASTWARD TRACK, MAKING LANDFALL AT 24H JUST SOUTH OF XIAMEN, CHINA, AND TRACK ALONG THE COASTLINE. THE MARGINALLY FAVORABLE ENVIRONMENT WILL SUSTAIN ITS CURRENT INTENSITY UP TO LANDFALL. AFTERWARD, LAND INTERACTION PLUS THE HIGH VWS WILL ERODE THE SYSTEM TOWARD DISSIPATION BY 96H, POSSIBLY SOONER.

13W(LUPIT).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A MIDGET SYSTEM THAT MAINTAINED OVERALL CONVECTIVE SIGNATURE OVER THE LAST SIX HOURS WITH THE MAIN FEEDER BAND WRAPPING IN FROM THE SOUTHWEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A DEFINED LOW LEVEL CIRCULATION FEATURE IN A CMA COMPOSITE RADAR LOOP. THE INITIAL INTENSITY IS BASED WITH HIGH CONFIDENCE ON OVERALL ASSESSMENT OF AGENCY DVORAK ESTIMATES AND EXTRAPOLATION FROM A NEARBY SHIP SURFACE WIND AND PRESSURE OBSERVATIONS AND REFLECTS THE SUSTAINED CONVECTIVE SIGNATURE. ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE TO HIGH VERTICAL WIND SHEAR AND PROXIMITY TO LAND OFFSET BY WARM SST AND MODERATE EQUATORWARD OUTFLOW.

13W.MODEL DISCUSSION: NUMERICAL MODELS ARE IN DISARRAY AFTER 24H WITH A SPREAD OF OVER 930 KM WITH GFS ON THE LEFT AND EGRR ON THE RIGHT MARGINS, LENDING LOW CONFIDENCE IN THE JTWC TACK FORECAST AFTER 24H (LANDFALL). THE CONFIDENCE IN THE INTENSIRY FORECAST IS ALSO LOW AFTER LANDFALL.

TD 14W. WARNING 2 ISSUED AT 04/15UTC.THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: AS TD 14W WILL TRACK NORTHWARD UP TO 12H AS THE STEERING MECHANISM SWITCHES TO A BUILDING SUBTROPICAL RIDGE (STR) TO THE EAST AND WILL BECOME THE PRIMARY STEERING FORCE THROUGHOUT THE FORECAST. AFTER 12H, IT WILL TURN NORTHEASTWARD AS THE STR REORIENTS AND EXTENDS SOUTHWESTWARD. BY 120H, TD 14W WILL BE APPROXIMATELY 455KM SOUTHEAST OF HOKKAIDO, JAPAN. THE FAVORABLE ENVIRONMENT WILL FUEL STEADY INTENSIFICATION TO A PEAK OF 55KNOTS BY 96H AS THE SYSTEM PASSES TO THE SOUTH OF TOKYO. AFTERWARD, INCREASING VERTICAL WIND SHEAR AND COOLING SSTS WILL WEAKEN THE SYSTEM DOWN TO 45KNOTS BY 120H. CONCURRENTLY BY 120H, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT ENTERS THE BAROCLINIC ZONE.

14W.SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A BROAD, ELONGATED, AND CONSOLIDATING SYSTEM EMBEDDED IN THE MONSOON TROUGH WITH SEVERAL WEAK VORTICES, ALONG THE TROUGH WITH ONE EXPOSED SPINNER TO THE WEST-NORTHWEST OF THE MAIN CONVECTION. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE ON THE CENTROID OF THE VORTICES, JUST TO THE WEST OF THE MAIN CONVECTION THAT IS BEGINNING TO WRAP. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE HELD HIGHER THAN AGENCY DVORAK BUT SUPPORTED BY NEARBY SURFACE OBSERVATIONS INCLUDING FROM NAHA, OKINAWA, AND REFLECTS THE IMPROVED CONSOLIDATION. THE SYSTEM IS IN A FAVORABLE ENVIRONMENT WITH LOW VWS, MODERATE EQUATORWARD OUTFLOW, AND WARM SSTS.

14W.MODEL DISCUSSION: THE AVAILABLE NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH THE SOLE EXCEPTION OF AFUM ON THE EXTREME LEFT MARGIN. IT ERRATICALLY DEFLECTS THE VORTEX SOUTHWESTWARD THEN DRIVES IT TOWARD RUSSIA. GIVEN THE LOW CONFIDENCE IN THE INITIAL POSITION AND THE UNCERTAINTIES IN THE STORM MOTION TYPICAL OF DEVELOPING SYSTEMS, THERE IS LOW CONFIDENCE IN THE TRACK FORECAST THAT IS LAID TO JUST TO THE RIGHT OF AND FASTER THAN THE MODEL CONSENSUS TO OFFSET AFUM. THE INTENSITY FORECAST IS HELD SLIGHTLY HIGHER THAN THE MODEL CONSENSUS; ALSO WITH LOW CONFIDENCE.

TD 15W. WARNING 1 ISSUED AT 04/15UTC.SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TD 15W WILL CONTINUE ON ITS CURRENT TRACK ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE(STR). AFTER 36H, IT WILL BEGIN TO ROUND THE STR AXIS THEN ACCELERATE NORTHEASTWARD THEN EASTWARD. AS THE SYSTEM TRACKS POLEWARD, VERTICAL WIND SHEAR(VWS) WILL INCREASE AS IT APPROACHES THE PREVAILING WESTERLIES. ADDITIONALLY, SSTS WILL BEGIN TO DROP. THE FAVORABLE ENVIRONMENT WILL QUICKLY BECOME MARGINAL BUT WILL STILL FUEL A SLIGHT INTENSIFICATION TO 35KNOTS FROM 12H TO 36H. AFTERWARD, THE COMBINED NEGATIVE EFFECTS OF HIGH VWS AND LOW SSTS WILL ERODE THE SYSTEM. THERE IS A POSSIBILITY THAT THE SYSTEM WILL DISSIPATE BEFORE THE END OF THE FORECAST PERIOD SHOULD THE MARGINAL ENVIRONMENT BECOME MORE UNFAVORABLE. OTHERWISE, BY 96H, THE TD WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AND TRANSFORM INTO A GALE- FORCE COLD CORE LOW BY 120H.

15W.SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A MEDIUM SIZED CONSOLIDATING SYSTEM TO THE EAST OF AN UPPER LEVEL LOW. THE INITIAL POSITION AND INTENSITY ARE EXTRAPOLATED WITH HIGH CONFIDENCE FROM A 040934UTC ASCAT BULLSEYE PASS. ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR, WARM SSTS, AND MODERATE RADIAL OUTFLOW TEMPERED BY SUBSIDENCE ALONG THE WESTERN FLANK DUE TO THE UPPER LEVEL LOW.

15W.MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT BUT LENDS HIGH CONFIDENCE TO THE JTWC TRACK FORECAST UP TO 72H ONLY DUE TO TRACK UNCERTAINTIES ASSOCIATED WITH EXTRA TROPICAL TRANSITION. THERE IS LOW CONFIDENCE IN THE INTENSITY FORECAST.

04/14UTC. CYCLONIC TRIO.

04/12UTC.