Tropical Storm MANGKHUT Advisory 9月12日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (MANGKHUT) WARNING
NR 20//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 26W (MANGKHUT), LOCATED APPROXIMATELY 268 NM
NORTH OF YAP, HAS TRACKED WESTWARD AT 14 KNOTS (KTS) OVER THE PAST
SIX HOURS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE USING
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY WHICH SHOWS A ROUND, 24
NM WIDE EYE AND INTENSE RAIN BANDS EXTENDING 200 NM FROM THE CENTER.
THE INITIAL INTENSITY OF 140 KNOTS IS CONSISTENT WITH DVORAK
ESTIMATES OF T7.0 (140 KTS) FROM PGTW, KNES, AND RJTD. THE
ENVIRONMENT REMAINS FAVORABLE WITH LOW VERTICAL WIND SHEAR (VWS),
WARM SEA SURFACE TEMPERATURE (29-30 C), AND EXCELLENT RADIAL
OUTFLOW. NOTABLY, POLEWARD OUTFLOW IS BEING AIDED BY TWO TUTT CELLS,
ONE TO THE NORTHWEST AND THE OTHER TO THE EAST. THE CYCLONE IS
TRACKING ALONG THE PERIPHERY OF A DEEP-LAYERED EAST-WEST ORIENTED
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS WARNING.
   B. STY 26W WILL TURN MORE WEST-NORTHWESTWARD AFTER TAU 12 AS THE
STR REORIENTS SLIGHTLY. CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS
WILL ALLOW STY 26W TO REACH A PEAK INTENSITY OF 150 KTS BY TAU 36
BEFORE REDUCED OUTFLOW BEGINS A WEAKENING TREND, FALLING TO 130 KTS
BY TAU 72. THE INTENSITY FORECAST IS ABOVE THE INTENSITY CONSENSUS
BUT THE CONSENSUS HAS BEEN CONSISTENTLY LOW FOR PAST WARNINGS ON
THIS CYCLONE. THE JTWC FORECAST TRACK FOLLOWS THE CONSENSUS WITH
HIGH CONFIDENCE BASED ON STRONG AGREEMENT IN THE NUMERICAL MODEL
GUIDANCE.
   C. AFTER TAU 72, STY 26W WILL CONTINUE TRACKING ALONG THE
PERIPHERY OF THE STR ON A NORTHWESTWARD TRACK, MAKING LANDFALL SOUTH
OF HONG KONG JUST PRIOR TO TAU 120. LAND INTERACTION, DRY AIR
ENTRAINMENT, AND DIMINISHED OUTFLOW WILL ACCELERATE WEAKENING,
BRINGING THE INTENSITY TO 75 KTS BY TAU 120. TRACK GUIDANCE REMAINS
IN STRONG AGREEMENT, WITH CTCX BEING A SLIGHT SOUTHERN OUTLIER,
THEREFORE CONFIDENCE IN THE JTWC FORECAST TRACK IS HIGH.//
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