Tropical Storm MANGKHUT Advisory Sat Sep 15

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (MANGKHUT) WARNING
NR 30//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON 26W (MANGKHUT), LOCATED APPROXIMATELY 297 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 15
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY INDICATES CLOUD TOPS IN STY 26W HAVE WARMED SLIGHTLY OVER
THE PAST SIX HOURS, AND THE SYSTEM HAS BECOME OBLONG, WITH A THINNER
BAND OF CONVECTION TO THE NORTHWEST. A 140444Z AMSR2 89GHZ MICROWAVE
IMAGE REVEALS CONCENTRIC EYEWALLS AND THE BEGINNING OF ANOTHER
EYEWALL REPLACEMENT CYCLE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE 30NM EYE. THE INITIAL INTENSITY IS ASSESSED
AT 145 KNOTS, BETWEEN THE PGTW DVORAK CURRENT INTENSITY ESTIMATE OF
T7.5 (155 KTS), THE RJTD ESTIMATE OF T7.0 (140 KTS), AND THE KNES
ESTIMATE OF T6.5 (127 KTS), BASED ON THE WARMING CLOUD TOPS AND
INITIATION OF THE ERC, WHICH WILL LEAD TO WEAKENING AS THE PRIMARY
EYEWALL IS STARVED OF INFLOW AND THE OUTER RING FURTHER FROM THE
CENTER BECOMES THE DOMINANT EYEWALL. A 140459Z SATCON ESTIMATE OF
142 KTS SUPPORTS THE INTENSITY ASSESSMENT. ENVIRONMENTAL ANALYSIS
SHOWS THAT THE SYSTEM CONTINUES TO LIE IN A FAVORABLE ENVIRONMENT
WITH STRONG RADIAL OUTFLOW, BUT THE TUTT CELL FAR TO THE EAST IS NO
LONGER ENHANCING ITS OUTFLOW. ADDITIONALLY, A WEAK UPPER-LEVEL
ANTICYCLONE CONTINUES TO IMPINGE UPON OUTFLOW IN THE NORTHWESTERN
QUADRANT. VERTICAL WIND SHEAR REMAINS LOW AND SSTS AND OHC REMAIN
SUPPORTIVE. STY 26W CONTINUES TO TRACK TO THE NORTHWEST
UNDER THE STEERING INFLUENCE OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR) ENTRENCHED TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
    B. STY 26W WILL TRACK WEST-NORTHWESTWARD THROUGH TAU 72 UNDER
THE INFLUENCE OF THE STR TO THE NORTHEAST. THE SYSTEM IS FORECAST TO
MAKE LANDFALL AS A VERY INTENSE SUPER TYPHOON ALONG THE NORTHEAST
COAST OF LUZON JUST AFTER TAU 12. ADDITIONAL NEAR-TERM WEAKENING IS
POSSIBLE BEFORE LANDFALL AS STY 26W PROCEEDS THROUGH ITS EYEWALL
REPLACEMENT CYCLE. AFTER MAKING LANDFALL, THE SYSTEM WILL WEAKEN
SIGNIFICANTLY AS IT INTERACTS WITH THE MOUNTAINOUS TERRAIN OF
NORTHERN LUZON. STY 26W WILL REEMERGE INTO THE SOUTH CHINA SEA (SCS)
JUST PRIOR TO TAU 24 AS A 105 KT SYSTEM. A PERIOD OF SLOW
INTENSIFICATION IS FORECAST IN THE SCS BETWEEN TAUS 24 AND 48 AS THE
SYSTEM MOVES OVER WARM (28-29 CELSIUS) WATERS AND UPPER LEVEL
OUTFLOW REMAINS FAVORABLE. STY 26W IS FORECAST TO MAKE LANDFALL
BETWEEN HONG KONG AND THE LEIZHOU PENINSULA AFTER TAU 48, WITH HWRF
THE NORTHERN OUTLIER MAKING LANDFALL CLOSER TO HONG KONG. DYNAMIC
MODEL GUIDANCE IS IN EXTREMELY TIGHT AGREEMENT THROUGH TAU 72, WITH
LESS THAN 15NM SPREAD AT LANDFALL, INCREASING TO 79NM AT TAU 48,
LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.
   C. AFTER TAU 72, STY 26W WILL CONTINUE ON A WEST-NORTHWESTWARD TO
WESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED
STR, WEAKENING RAPIDLY OVER THE MOUNTAINOUS TERRAIN OF NORTHERN
VIETNAM, CHINA, AND NORTHERN MYANMAR, DISSIPATING BY TAU 120.
DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT IN THE LATER TAUS, WITH
SOME MODELS LOSING THE SYSTEM AND OTHERS BRINGING IT TO THE
NORTHWEST. OVERALL HOWEVER, THERE IS HIGH CONFIDENCE IN THE OFFICIAL
FORECAST THROUGH TAU 96, WITH LOW CONFIDENCE THEREAFTER.//
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