Tropical Storm MANGKHUT Advisory Wed Sep 12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (MANGKHUT) WARNING
NR 21//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 26W (MANGKHUT), LOCATED APPROXIMATELY 287 NM
NORTH-NORTHWEST OF YAP, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE
PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
USING ANIMATED MULTISPECTRAL SATELLITE IMAGERY WHICH SHOWS A ROUND,
26 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 IS FAVORABLE WITH LOW (10 KTS) VERTICAL WIND SHEAR
(VWS), WARM SEA SURFACE TEMPERATURE (29-30 C), AND EXCELLENT RADIAL
OUTFLOW. POLEWARD OUTFLOW IS BEING ENHANCED 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. BY TAU 12, STY 26W WILL HAVE TURNED WEST-NORTHWESTWARD AS THE
STR REORIENTS. CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS WILL
ALLOW STY 26W TO INTENSIFY SLIGHTLY, REACHING A PEAK INTENSITY OF
145 KTS BY TAU 12 BEFORE THE POLEWARD OUTFLOW BECOMES LESS ENHANCED.
BY TAU 72, LAND INTERACTION WITH LUZON WILL HELP REDUCE THE
INTENSITY TO 120 KTS. THE INTENSITY FORECAST IS HEDGED TO THE HIGH
SIDE OF THE INTENSITY GUIDANCE ENVELOPE AND IS 5 TO 15 KTS ABOVE THE
CONSENSUS. THE MODEL TRACK GUIDANCE IS IN EXCELLENT AGREEMENT, WITH
JUST OVER 70 NM OF SPREAD BY TAU 72. FOR THAT REASON, CONFIDENCE IS
HIGH IN THE JTWC FORECAST TRACK WHICH CLOSELY FOLLOWS THE CONSENSUS.
   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 SHORTLY AFTER TAU 96. LAND INTERACTION, DRY AIR
ENTRAINMENT, AND DIMINISHED OUTFLOW WILL ACCELERATE WEAKENING,
BRINGING THE INTENSITY TO 70 KTS BY TAU 120. TRACK GUIDANCE REMAINS
IN STRONG AGREEMENT, WITH CTCX AND JGSM BEING SLIGHT SOUTHERN
OUTLIERS, THEREFORE CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH
CLOSELY FOLLOWS THE CONSENSUS, IS HIGH.//
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