Tropical Storm BAVI Advisory 8月22日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE) WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 09W (NINE), LOCATED APPROXIMATELY 366 NM SOUTHWEST OF KADENA AB, OKINAWA, HAS TRACKED NORTHWARD AT 10 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND ANIMATED RADAR IMAGERY SHOW A CONSOLIDATING LOW LEVEL CIRCULATION WITH DEEP CONVECTIVE BANDING IN THE SOUTHERN AND EASTERN SEMICIRCLES. BASED ON THIS IMAGERY, ALONG WITH A 211727Z AMSR2 89 GHZ MICROWAVE IMAGE SHOWING BANDING WRAPPING INTO A CONSOLIDATING SYSTEM, THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY IS SET AT 25 KTS, SUPPORTED BY SUBJECTIVE AND OBJECTIVE DVORAK INTENSITY ESTIMATES RANGING FROM T1.5 (25KTS, PGTW/RJTD) TO T1.7 (27 KTS, ADT). UPPER LEVEL ENVIRONMENTAL ANALYSIS REVEALS LOW TO MODERATE (10-20 KTS) VERTICAL WIND SHEAR (VWS) AND ESTABLISHED EQUATORWARD OUTFLOW. AN UPPER-LEVEL LOW TO THE NORTHEAST IS ENHANCING THE DEVELOPMENT OF POLEWARD OUTFLOW. TD 09W IS TRANSITING THROUGH A REGION OF WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES (SST) AND HIGH OCEAN HEAT CONTENT VALUES. THUS, THE ENVIRONMENT IS HIGHLY FAVORABLE FOR CONTINUED DEVELOPMENT. THE SYSTEM IS TRACKING ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE EAST THAT HAS AN EXTENSION TO THE NORTH OF THE SYSTEM AS WELL.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. IN THE NEAR-TERM, THE WEAK STR EXTENSION IS EXPECTED TO ERODE TO THE NORTH OF TD 09W AS A SHORTWAVE TROUGH DIGS OVER THE EAST CHINA SEA. THIS EROSION WILL CAUSE A REORIENTATION OF THE STEERING STR, TRACKING TD 09W NORTHEASTWARD FROM TAU 24 TO TAU 48. THE EASTWARD PROPAGATING TROUGH WILL ENHANCE THE POLEWARD OUTFLOW CHANNEL, ALLOWING TD 09W TO RAPIDLY INTENSIFY TO 100 KTS BY TAU 72. WITH SLIGHT VARIATIONS IN THE TIMING OF THE RECURVES, DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A SPREAD OF 80 NM AT TAU 48 AND 130 NM AT TAU 72.
   C. AS THE TROUGH PASSES, THE STR WILL BUILD OVER WESTERN JAPAN AND CAUSING TD 09W TO TRACK NORTHWARD ALONG THE WESTERN PERIPHERY TOWARDS SOUTH KOREA. AFTER THE SYSTEM REACHES A PEAK INTENSITY OF 105 KTS BY TAU 96, ENVIRONMENTAL CONDITIONS WILL BEGIN TO DEGRADE SLOWLY THEN MORE RAPIDLY AS THE TD 09W BEGINS TO INTERACT WITH THE KOREAN PENINSULA AND INCREASING VWS. HOWEVER, MODEL GUIDANCE INDICATES THAT THERE IS UNCERTAINTY IN THE PRECISE LANDFALL LOCATION. OVERALL, THERE IS MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK.//
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