WTIO31 PGTW 182100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 01B (AMPHAN) WARNING NR 011// RMKS/ 1. TROPICAL CYCLONE 01B (AMPHAN) WARNING NR 011 01 ACTIVE TROPICAL CYCLONE IN NORTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 181800Z --- NEAR 14.8N 86.5E MOVEMENT PAST SIX HOURS - 015 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 010 NM POSITION BASED ON EYE FIXED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 175 NM SOUTHWEST QUADRANT 180 NM NORTHWEST QUADRANT REPEAT POSIT: 14.8N 86.5E --- FORECASTS: 12 HRS, VALID AT: 190600Z --- 16.4N 86.9E MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 200 NM SOUTHEAST QUADRANT 170 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 015 DEG/ 11 KTS --- 24 HRS, VALID AT: 191800Z --- 18.5N 87.5E MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 190 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 015 DEG/ 11 KTS --- 36 HRS, VALID AT: 200600Z --- 20.6N 88.1E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 015 DEG/ 12 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 201800Z --- 23.0N 88.8E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 025 DEG/ 08 KTS --- 72 HRS, VALID AT: 211800Z --- 26.0N 90.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 182100Z POSITION NEAR 15.2N 86.6E. 18MAY20. TROPICAL CYCLONE 01B (AMPHAN), LOCATED APPROXIMATELY 480 NM SOUTH-SOUTHWEST OF KOLKATA, INDIA, HAS TRACKED NORTH- NORTHEASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES THAT TC 01B HAS SIGNIFICANTLY WEAKENED OVER THE PAST SIX HOURS, IN RESPONSE TO AN EYEWALL REPLACEMENT CYCLE, WITH THE EYE ACTUALLY FILLING AND DISAPPEARING FROM INFRARED IMAGERY OVER THE PAST HOUR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE 9 NM EYE EVIDENT IN GOES-IO SATELLITE, SUPPORTED BY FIRST INDICATIONS OF THE INNER EYE ON IMD RADAR DATA. THERE HAVE BEEN NO MICROWAVE PASSES SINCE A 1514Z AMSU-B 89 GHZ IMAGE WHICH SHOWED THAT THE INNER EYEWALL HAS BROKEN DOWN ON THE EASTERN SIDE AS WELL AS INDICATIONS OF THE SECONDARY EYEWALL FORMING, ALSO OPEN ON THE EASTERN SIDE. THE LAST GOOD HIGH RESOLUTION MICROWAVE WAS A 1211Z CORIOLIS 37 GHZ COLORIZED IMAGE WHICH SHOWED THE SECONDARY EYEWALL FORMING ABOUT 25 NM OUT FROM THE CENTER, LENDING HIGH CONFIDENCE TO THE ASSESSMENT OF ONGOING ERC. THE INITIAL INTENSITY OF 130 KNOTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 6.0/6.5 DVORAK ESTIMATE FROM PGTW, AND A 6.5 CURRENT INTENSITY ESTIMATE FROM DEMS AT 1200Z. THE ADVANCED DVORAK TECHNIQUE CURRENT INTENSITY REMAINS AT 7.1, BUT THE FINAL T-NUMBER WAS ALSO 6.5 AT 1800Z. ANALYSIS REVEALS THAT TC 01B REMAINS IN A GENERALLY FAVORABLE ENVIRONMENT, WITH LOW (15-20 KNOTS) VWS, VERY WARM (31-32 CELSIUS) SSTS AND STRONG POLEWARD AND MODERATE EQUATORWARD OUTFLOW. THE SYSTEM IS CURRENTLY TRACKING NORTHWARD ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED EXTENSION OF THE NER CENTERED NEAR THE GULF OF THAILAND. TC 01B IS FORECAST TO CONTINUE TRACKING NORTH-NORTHEASTWARD THROUGH THE DURATION OF THE FORECAST ALONG THE PERIPHERY OF THE PREVIOUSLY MENTIONED NER. THE SYSTEM IS EXPECTED TO MAKE LANDFALL SOUTH OF KOLKATA, INDIA ROUGHLY NEAR TAU 40. AS PREVIOUSLY DISCUSSED, THE SYSTEM IS CURRENTLY UNDERGOING AN EYEWALL REPLACEMENT CYCLE WHICH HAS RESULTED IN THE CURRENT WEAKENING TREND. THE ERC IS EXPECTED TO COMPLETE BEFORE TAU 24 WITH A NEW, MUCH BROADER EYE REFORMING, WHICH WILL SERVE TO ARREST THE WEAKENING TREND FOR A SHORT PERIOD OF TIME BETWEEN TAUS 12 AND 24. AS THE SYSTEM CONTINUES TRACKING NORTHWARD VWS IS FORECAST TO INCREASE, HOWEVER THE UPPER-LEVEL WINDS ARE EXPECTED TO VEER OVER TIME, WITH THE SHEAR VECTOR BECOMING MORE IN PHASE WITH THE STORM TRACK THROUGH LANDFALL, LOWERING THE EFFECTIVE VWS TO LOW-MODERATE LEVELS. WITH VERY WARM WATERS EXTENDING ALL THE WAY TO THE COAST, AND ROBUST POLEWARD OUTFLOW, THE MAINTENANCE OF MORE MODERATE LEVELS OF RELATIVE VWS WILL ALLOW THE SYSTEM TO MAINTAIN A SLIGHTLY HIGHER INTENSITY THROUGH LANDFALL. AFTER LANDFALL THE SYSTEM WILL CONTINUE TRACKING NORTHEASTWARD AND RAPIDLY DISSIPATE DUE TO LAND INTERACTION AND STEADILY INCREASING VWS FROM THE WEST. TRACK GUIDANCE IS IN TIGHT AGREEMENT WITH ONLY 27 NM OF SPREAD AT TAU 48 WITH ECMWF ON THE RIGHT AND GFS ON THE LEFT OF THE VERY TIGHT ENVELOPE. AFTER LANDFALL SPREAD INCREASES SIGNIFICANTLY AS MODELS STRUGGLE TO TRACK THE VORTEX. THERE IS HIGH CONFIDENCE IN THE JTWC TRACK WHICH HUGS THE EASTERN EDGE OF THE GUIDANCE ENVELOPE CLOSER TO THE ECMWF SOLUTION. INTENSITY GUIDANCE IS MORE MIXED, THOUGH MOST INDICATE A STEADY WEAKENING TREND, WITH HWRF BEING THE SOLE OUTLIER ON THE HIGH SIDE, EVEN SHOWING SOME INTENSIFICATION IN THE NEAR TERM. THE JTWC INTENSITY FORECAST LIES JUST SLIGHTLY BELOW THE MULTI-MODEL CONSENSUS THROUGH TAU 12, THEN ABOVE IT AND CLOSER TO THE HWRF SOLUTION THROUGH THE REMAINDER OF THE FORECAST WITH MODERATE CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 181800Z IS 52 FEET. NEXT WARNINGS AT 190300Z, 190900Z, 191500Z AND 192100Z.// NNNN