Tropical Storm BAVI Advisory 8月25日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 09W (BAVI), LOCATED APPROXIMATELY 155 NM NORTHWEST
OF KADENA AB, OKINAWA, HAS TRACKED NORTH-NORTHWESTWARD AT 03 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS IMPROVED CONVECTIVE ORGANIZATION WITH A NEWLY FORMED
5NM RAGGED EYE EVIDENT. A 241756Z AMSR2 36GHZ IMAGE DEPICTS A
COMPACT EYEWALL SURROUNDING A SMALL MICROWAVE EYE FEATURE AND SPIRAL
BANDING OVER THE SOUTHERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL
POSITION AND RECENT STORM MOTION WITH HIGH CONFIDENCE. THE 34- AND
50-KNOT WIND RADII HAVE BEEN ADJUSTED BASED ON A DETAILED ANALYSIS
OF A 241309Z ASCAT-B 25-KM BULLSEYE IMAGE. THE INITIAL INTENSITY IS
ASSESSED AT 90 KNOTS BASED ON A PGTW DVORAK ESTIMATE OF T5.0 (90
KNOTS) AND IS SLIGHTLY HIGHER THAN A 241716Z SATCON ESTIMATE OF 83
KNOTS. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH MODERATE (20-
25 KNOTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY ROBUST
EQUATORWARD OUTFLOW, IMPROVING POLEWARD OUTFLOW AND WARM (30C) SST.
TY 09W IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND
NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 09W WILL CONTINUE TO TRACK POLEWARD OVER THE NEXT 72
HOURS ALONG THE WESTERN PERIPHERY OF THE BUILDING STR TO THE EAST.
NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 48 WITH A
45NM SPREAD IN SOLUTIONS AT TAU 48. ADDITIONALLY, THE ECMWF ENSEMBLE
SOLUTIONS ARE ALSO IN GOOD AGREEMENT REFLECTING A HIGH CONFIDENCE
(LOW UNCERTAINTY) FORECAST TRACK. AFTER TAU 48, THE DYNAMIC MODEL
SOLUTIONS DIVERGE AS THE SYSTEM UNDERGOES EXTRA-TROPICAL TRANSITION
AND TRACKS INTO NORTHEAST CHINA. THERE IS SIGNIFICANT UNCERTAINTY,
HOWEVER, IN THE JTWC INTENSITY FORECAST. TY 09W HAS FLIRTED WITH AN
EYE OVER THE PAST SIX HOURS WITH UNOFFICIAL DVORAK ESTIMATES PEAKING
CLOSE TO A T5.5 (102 KNOTS) AND ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO IMPROVE WITH DECREASING VWS AND IMPROVED OUFLOW INTO A
MIDLATITUDE SHORTWAVE TROUGH FORECAST WITHIN THE NEXT 12 TO 24
HOURS. ADDITIONALLY, THE RAPID INTENSIFICATION AIDS HAVE TRIGGERED
INDICATING POTENTIAL FOR A SPIKE IN INTENSITIES. THEREFORE, THE PEAK
INTENSITY IS HELD AT 115 KNOTS AT TAU 24 THEN GRADUAL WEAKENING AS
THE SYSTEM ENCOUNTERS COOLER SST (28-25C) OVER THE NORTHERN YELLOW
SEA AND STRONG VWS AFTER TAU 36. TY 09W SHOULD COMPLETE EXTRA-
TROPICAL TRANSITION BY TAU 72 AS IT GAINS FRONTAL CHARACTERISTICS
AND NEARS THE JET. OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK WHICH IS POSITIONED NEAR THE MULTI-MODEL CONSENSUS.//
NNNN
NNNN