18W(NORU): current Extreme Rapid Intensification(ERI) to reach Super Typhoon intensity, 3rd of the season,2421utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 18W(NORU).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: SUPER TYPHOON (STY) 18W HAS UNDERGONE EXTREME RAPID INTENSIFICATION (ERI) FROM 45 KNOTS AT 231800Z TO THE CURRENT INTENSITY OF 135 KNOTS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A NEAR SYMMETRIC CENTRAL DENSE OVERCAST WITH A SMALL, OBLONG EYE (5-8NM DIAMETER) WITH SPIRAL BANDING. OVER THE PAST FEW HOURS, EIR INDICATES TROCHOIDAL MOTION AS THE SYSTEM TURNS GRADUALLY WESTWARD AND TRACKS TOWARD DINGALAN BAY. IN GENERAL, STY 18W HAS MAINTAINED A WARM EYE WITH THE EYE TEMPERATURE VARYING FROM 8.7C TO 16.0C (THE 241950Z EYE TEMPERATURE IS 11.9C) WITH DVORAK DATA-T ESTIMATES RANGING FROM DT6.5 TO DT7.0 (127 TO 140 KNOTS) SINCE ABOUT 241730Z. THE DVORAK FINAL-T ESTIMATES (BELOW) ARE CONSERVATIVE AND HELD LOWER DUE TO CONSTRAINTS. ADT CURRENT INTENSITY ESTIMATES ARE ALSO CONSERVATIVE WHILE RAW-T NUMBERS HAVE VARIED FROM 6.8 TO 7.0 (135 TO 140 KNOTS). THE INITIAL INTENSITY IS ASSESSED ABOVE THE FINAL-T ESTIMATES BASED ON MULTIPLE, VERY CONSISTENT DVORAK DATA-T ESTIMATES AS WELL AS THE ADT RAW-T VALUES, HOWEVER, THERE IS SOME UNCERTAINTY IN THE EXACT INTENSITY THUS MEDIUM OVERALL CONFIDENCE. ENVIRONMENTAL CONDITIONS ARE HIGHLY FAVORABLE WITH RADIAL OUTFLOW, LOW VERTICAL WIND SHEAR, WARM SST VALUES AND HIGH OCEAN HEAT CONTENT.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE MAJOR CHANGES TO THE INTENSITY FORECAST DUE TO THE ERI PHASE OVER THE PAST 24 HOURS. FORECAST DISCUSSION: STY 18W BEARS MANY SIMILARITIES TO STY GONI (2020), WHICH UNDERWENT ERI WHILE TURNING WEST-SOUTHWESTWARD TOWARD SOUTHERN LUZON, HOWEVER, STY GONI ATTAINED STY STRENGTH TWO DAYS PRIOR TO LANDFALL SO PEAKED MUCH HIGHER. STY 18W IS FORECAST TO TRACK WESTWARD AND MAKE LANDFALL IN ABOUT 15 TO 18 HOURS WITH A PEAK INTENSITY OF 145 KNOTS EXPECTED AT TAU 12. AFTER MAKING LANDFALL, STY 18W WILL WEAKEN RAPIDLY AS IT CROSSES THE PHILIPPINE ISLANDS, DOWN TO ABOUT 100 KNOTS BY TAU 36. MORE SIGNIFICANT WEAKENING IS POSSIBLE. AFTER RE-EMERGING OVER THE SOUTH CHINA SEA, STY 18W IS FORECAST TO RE-INTENSIFY TO A PEAK INTENSITY OF 115 KNOTS JUST PRIOR TO LANDFALL OVER CENTRAL VIETNAM NEAR TAU 72. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN FAVORABLE ALTHOUGH VERTICAL WIND SHEAR IS EXPECTED TO GRADUALLY INCREASE TO 15-20 KNOTS BY LANDFALL.

TPPN11 PGTW 242142 A. SUPER TYPHOON 18W (NORU) B. 24/2040Z C. 14.99N D. 124.23E E. ONE/HMWRI8 F. T7.0/7.0/D4.0/24HRS STT: D0.5/03HRS G. IR/EIR H. REMARKS: 05A/PBO IRREG EYE/ANMTN. WMG EYE SURROUNDED BY W YIELDS AN E# OF 6.0. ADDED 1.0 EYE ADJUSTMENT FOR CMG, TO YIELD A DT OF 7.0. MET YIELDS 4.5. PT YIELDS 6.0. CONSTRAINTS BROKEN FOR RAPID INTENSIFICATION. DBO DT. I. ADDITIONAL POSITIONS: 24/1705Z 15.18N 124.87E GPMI HEINS

24/1936UTC

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH A 30-40NM SPREAD IN SOLUTIONS THROUGH TAU 18, AND AN 80-90NM SPREAD IN SOLUTIONS THROUGH THE REMAINDER OF THE FORECAST THUS OVERALL HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. DUE TO THE POTENTIAL FOR MORE SIGNIFICANT WEAKENING OVER THE PHILIPPINE ISLANDS AND POTENTIAL FOR RAPID INTENSIFICATION OVER THE SOUTH CHINA SEA, THERE IS LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST. RELIABLE INTENSITY GUIDANCE INDICATES A STEEP DROP IN INTENSITY AS THE SYSTEM TRACKS OVER LAND WITH A RANGE OF 55 (HWRF) TO 85 (COAMPS-TC) KNOTS WITH RE-INTENSIFICATION TO 90-115 KNOTS. THE 241200Z COAMPS-TC ENSEMBLE INDICATES A 40 TO 60 PERCENT PROBABILITY OF RAPID INTENSIFICATION IN THE TAU 48 TO TAU 60 TIMEFRAME.

THE AREA OF CONVECTION (INVEST 96W) PREVIOUSLY LOCATED NEAR 12.8N 147.7E IS NOW LOCATED NEAR 15.4N 145.7E, APPROXIMATELY 138 NM NORTH-NORTHEAST OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 241532Z GMI 89GHZ MICROWAVE IMAGE DEPICT FLARING DEEP CONVECTION OVER A BROAD DISORGANIZED CORE. A RECENT SCATTEROMETRY PASS REVEALS AN ELONGATED CIRCULATION EAST OF THE MARIANA ISLANDS WITH A SWATH OF 25KT WINDS TO THE EASTERN PERIPHERY. INVEST 96W IS EMBEDDED WITHIN THE EASTERN PERIPHERY OF THE MONSOON TROUGH, WHICH HAS MAINTAINED EXTENSIVE CONVERGENT WESTERLIES AND SOUTHERLIES ALONG THE SOUTHERN AND EASTERN PERIPHERIES. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR DEVELOPMENT AS CHARACTERIZED BY WARM (29-30C) SST, LOW (10-15KT) VERTICAL WIND SHEAR, AND STRONG EQUATORWARD AND POLEWARD OUTFLOW. GLOBAL MODELS ARE IN RELATIVELY GOOD AGREEMENT THAT OVERALL CONDITIONS ARE FAVORABLE FOR DEVELOPMENT WITHIN 24-48 HOURS AS INVEST 96W TRACKS NORTH-NORTHWESTWARD WHILE QUICKLY INTENSIFYING. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

GLOBAL MODELS ARE IN RELATIVELY GOOD AGREEMENT THAT OVERALL CONDITIONS ARE FAVORABLE FOR DEVELOPMENT WITHIN 24-48 HOURS AS INVEST 96W TRACKS NORTH-NORTHWESTWARD WHILE QUICKLY INTENSIFYING.