Tropical Storm LINGLING Advisory 9月5日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (LINGLING) WARNING NR 12//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 15W (LINGLING), LOCATED APPROXIMATELY 222 NM
SOUTHWEST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWARD AT 05
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS THE SYSTEM HAS BEGUN TO TRACK MORE POLEWARD AFTER A
MOMENTARY 12-HR NORTHEASTWARD JOG. TIGHTLY-CURVED BANDS, MOSTLY FROM
THE SOUTH TO SOUTHWEST WRAPPED TIGHTER INTO A WELL-DEFINED 20NM EYE.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE
FEATURE THAT LINED UP PERFECTLY WITH A SHARPLY-OUTLINED CIRCULATION
FEATURE IN A COMPOSITE RADAR LOOP FROM JMA. THE INITIAL INTENSITY OF
90KTS IS BASED ON DVORAK INTENSITY ESTIMATES OF T5.0/90KTS FROM PGTW,
RJTD, AND RCTP. UPPER-LEVEL ANALYSIS INDICATES A GENERALLY FAVORABLE
ENVIRONMENT WITH LOW TO MODERATE (15-20KT) VERTICAL WIND SHEAR (VWS)
OFFSET BY VIGOROUS EQUATORWARD OUTFLOW. SEA SURFACE TEMPERATURES
(SSTS) AT 28-29C REMAIN CONDUCIVE. TY 15W HAS TURNED NORTHWARD AS THE
SUBTROPICAL RIDGE (STR) TO THE EAST ASSUMED STEERING.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 15W WILL CONTINUE NORTHWARD UNDER THE STR. AFTER TAU 48, IT
WILL TRACK MORE NORTH-NORTHEASTWARD IN THE YELLOW SEA AS THE STR
RECEDES EASTWARD IN RESPONSE TO A MIDLATITUDE TROUGH APPROACHING FROM
THE NORTHWEST, MAKING LANDFALL OVER THE SOUTH COAST OF NORTH KOREA
NEAR HAEJU SHORTLY AFTER TAU 60. THE OVERALL FAVORABLE ENVIRONMENT
WILL PROMOTE A STEADY INTENSIFICATION TO A PEAK OF 105KTS AT TAUS
24-36. AFTERWARD, INCREASING VWS AND COOLING SSTS IN THE YELLOW SEA
WILL BEGIN TO WEAKEN THE SYSTEM. BY TAU 72, AS TY 15W DRAGS ACROSS
THE RUGGED TERRAIN OF CENTRAL NORTH KOREA, IT WILL COMMENCE
EXTRA-TROPICAL TRANSITION (ETT). NUMERICAL MODELS ARE IN TIGHT
AGREEMENT LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK
FORECAST.
   C. AFTER TAU 72, TY LINGLING WILL ACCELERATE NORTHEASTWARD AND
COMPLETE ETT BY TAU 96 NORTH OF VLADIVOSTOK, RUSSIA. CONCURRENTLY,
RAPID WEAKENING IS EXPECTED AS THE SYSTEM ENCOUNTERS INCREASING VWS
AND RUGGED TERRAIN. NUMERICAL MODELS REMAIN IN GOOD AGREEMENT WITH
GFS AS THE NOTABLE RIGHT-OF-TRACK OUTLIER. DUE TO UNCERTAINTY IN
TRACK SPEEDS OVER RUGGED TERRAIN, THERE IS MODERATE CONFIDENCE IN
THIS EXTENDED PORTION OF THE JTWC FORECAST THAT IS LAID JUST LEFT OF
MODEL CONSENSUS TO OFFSET THE UNLIKELY GFS TRACK INTO THE STR.//
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