Tropical Storm KALMAEGI Advisory 15 Σεπ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KALMAEGI) WARNING
NR 17//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 15W (KALMAEGI), LOCATED APPROXIMATELY 783 NM
EAST OF HANOI, VIETNAM, HAS TRACKED WESTWARD AT 19 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
INDICATES SIGNIFICANT WEAKENING OF THE CONVECTIVE STRUCTURE AS THE
SYSTEM CROSSED LUZON. A 141738Z AMSU IMAGE DEPICTS A WEAK MICROWAVE
EYE FEATURE SURROUNDED BY FRAGMENTED BANDING AND A DEEP CONVECTIVE
BAND OVER THE SOUTHERN SEMI-CIRCLE WRAPPING INTO THE SOUTHEAST
QUADRANT OF THE SYSTEM. DUE TO THE LACK OF HIGH RESOLUTION MICROWAVE
IMAGERY AND DEGRADED ORGANIZATION, THERE IS FAIR CONFIDENCE IN THE
INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 60 KNOTS
BASED ON AN AVERAGE OF DVORAK INTENSITY ESTIMATES RANGING FROM T3.5
(55 KNOTS) TO T4.0 (65 KNOTS). RECENT 500 MB ANALYSES SHOW A STRONG,
BROAD, EAST-WEST ORIENTED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE
NORTH AND NORTHWEST.
 3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 15W IS FORECAST TO ACCELERATE WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STRONG STR THROUGH TAU 72. TS 15W IS
FORECAST TO INTENSIFY THROUGH TAU 24, PRIOR TO MAKING LANDFALL OVER
NORTHERN HAINAN NEAR TAU 30, DUE TO FAVORABLE ENVIRONMENTAL
CONDITIONS TO INCLUDE WARM SST AND FAVORABLE OUTFLOW. NEAR TAU 36,
TS KALMAEGI IS FORECAST TO WEAKEN AS IT APPROACHES THE COAST OF
VIETNAM AND SHOULD DISSIPATE BY TAU 72 AS IT TRACKS WELL INLAND.
DYNAMIC MODEL GUIDANCE (INCLUDING THE MODEL ENSEMBLES) IS IN TIGHT
AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK, WHICH IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.//
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