Tropical Storm MERANTI Advisory ср, 14.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 16W (MERANTI) WARNING NR
21//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 16W (MERANTI), LOCATED APPROXIMATELY 259 NM
SOUTH OF TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS THAT THE SYSTEM HAS CONTINUED TO INTENSITY WITH A DEEP
EXPANSIVE CORE OF CONVECTION SURROUNDING A SHARP 15NM EYE. THE
TAIWAN RADAR LOOP AND A SERIES OF MICROWAVE IMAGES SHOW A VERY
INTENSE CONVECTIVE RING SURROUNDING THE EYE FEATURE WHICH SUPPORTS
THE CURRENT POSITION WITH HIGH CONFIDENCE. THE 131650Z AMSR-2 91GHZ
MICROWAVE IMAGE REVEALS THAT THE CYCLONE IS BEGINNING TO UNDERGO AN
EYEWALL REPLACEMENT CYCLE WITH A SECOND CONVECTIVE RING ALMOST
COMPLETELY SURROUNDING THE INNER RING. THE EIR AND THE RADAR LOOPS
BOTH DEPICT TROCHOIDAL EYE MOTION WHICH MAY IMPACT THE CPA TO
TAIWAN AS IT PASSES TO THE SOUTH. THE INITIAL INTENSITY IS BASED ON
AN ASSESSMENT OF CURRENT INTENSITY ESTIMATES FROM RJTD AND PGTW AS
WELL AS A SATCON INTENSITY ESTIMATE ABOVE 170 KNOTS. STY 16W
MAINTAINS A VERY FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR
(VWS), STRONG RADIAL OUTFLOW, AND VERY WARM SEA SURFACE
TEMPERATURES. HOWEVER, BETWEEN THE LAND INTERACTION WITH TAIWAN AND
THE IMPENDING EYEWALL REPLACEMENT CYCLE, THE SYSTEM HAS REACHED ITS
PEAK INTENSITY. STY 16W IS UNDER THE STEERING INFLUENCE OF A
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. STY 16W WILL TRACK GENERALLY WEST-NORTHWESTWARD THROUGHOUT THE
FORECAST UNDER THE STEERING INFLUENCE OF THE STR. THE COMBINED
EFFECTS OF INCREASING VWS, LAND INTERACTION, AND THE EYEWALL
REPLACEMENT CYCLE WILL ALL SERVE TO WEAKEN THE SYSTEM AS IT
APPROACHES CHINA. JUST AFTER TAU 24, STY MERANTI WILL MAKE LANDFALL
IN CHINA AS A STRONG TYPHOON. THE RUGGED TERRAIN AND INCREASED VWS
WILL RAPIDLY ERODE THE SYSTEM, DISSIPATING IT AS A SIGNIFICANT
CYCLONE OVER LAND BY TAU 48. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST UP TO
LANDFALL IN CHINA WHERE TRACK VARIABILITY IS HIGH DUE TO THE
FORECASTED RAPID DISSIPATION.//
NNNN
NNNN