Tropical Storm MAYSAK Advisory Tue Sep 01

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (MAYSAK) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 10W (MAYSAK), LOCATED APPROXIMATELY 93 NM WEST-
NORTHWEST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTH-
NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED A
RAGGED PINHOLE EYE, NOW SHRUNK TO A 06-NM DIAMETER. SPIRAL BANDS
ALSO REMAIN TIGHTLY WRAPPED INTO A COMPACT CENTRAL CONVECTION. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE
FEATURE, ADJUSTED FOR A SLIGHT WESTWARD TILT. THE INITIAL INTENSITY
OF 115 KTS IS BASED THE DVORAK ESTIMATES OF T6.0/115KTS FROM RJTD
AND PGTW. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT
WITH A ROBUST RADIAL OUTFLOW AND LOW (10-15KT) VERTICAL WIND SHEAR
(VWS). HOWEVER, HIGHER VWS VALUES ARE IMMINENTLY DOWNSTREAM. SEA
SURFACE TEMPERATURES (SST) ARE STILL WARM AT 29-30C AND OCEAN HEAT
CONTENT (OHC) VALUES ARE STILL HIGH. TY 10W IS TRACKING UNDER THE
COMBINED STEERING INFLUENCE OF TWO SUBTROPICAL RIDGES (STR): ONE TO
THE NNE AND ANOTHER TO THE ESE.
3. FORECAST REASONING.
   A. THIS FORECAST HIGHLIGHTS ANEW THE TRANSITION TO AN EXTRA-
TROPICAL SYSTEM BY TAU 48, OTHERWISE, THERE IS NO CHANGE TO THE
FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY MAYSAK WILL BEGIN TO TURN ON A MORE POLEWARD TRAJECTORY AS
THE STR TO THE ESE RECEDES EQUATORWARD AND THE STR TO THE NNE
ADJUSTS EASTWARD, BUILDS, AND BECOMES THE PRIMARY STEERING
MECHANISM. INCREASING VWS, DECREASING OHC VALUES, AND COOLING SSTS
WILL GRADUALLY WEAKEN THE SYSTEM TO 90 KTS BY TAU 36 JUST BEFORE
LANDFALL INTO SOUTH KOREA. AFTER LANDFALL, LAND INTERACTION OVER THE
RUGGED MOUNTAIN RANGES OF THE KOREAN PENINSULA, AND STRONG VWS WILL
RAPIDLY ERODE TY 10W DOWN TO 60 KTS AS IT MOMENTARILY SPLASHES INTO
THE SEA OF JAPAN AROUND TAU 48, THEN DOWN TO 30 KTS AFTER TAU 72
AFTER IT CROSSES INTO MANCHURIA. CONCURRENTLY AT TAU 36, THE SYSTEM
WILL COMMENCE EXTRATROPICAL TRANSITION (ETT) AS IT INTERACTS WITH
THE MIDLATITUDE TROUGH APPROACHING FROM THE NORTHWEST, COMPLETING
ETT BY TAU 48, BECOMING AN INTENSE COLD CORE LOW. THERE IS A
DISTINCT POSSIBILITY OF DISSIPATION OVER THE RUGGED TAEBAEK MOUNTAIN
RANGES PRIOR TO TAU 72. THE NUMERICAL MODELS REMAIN IN TIGHT
AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK
THAT IS LAID SLIGHTLY LEFT OF THE MULTI-MODEL CONSENSUS TO OFFSET
AFUM, THE EXTREME RIGHT-OF-TRACK OUTLIER THAT IS UNREALISTICALLY
DRIVING THE VORTEX INTO THE STR.//
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