Tropical Storm YUTU Advisory Sat Oct 27

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (YUTU) WARNING NR
23//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 31W (YUTU), LOCATED APPROXIMATELY 811 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) SHOWS A MORE SYMMETRIC SYSTEM THAT HAS MAINTAINED A RAGGED
27-NM EYE WITH COMPACT RAIN BANDS WRAPPING TIGHTLY INTO THE CENTRAL
CONVECTION WITH SUPER-DEEP AND COLD CLOUD TOPS (-82 CELSIUS). THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI EYE
THAT LINED UP PERFECTLY WITH A MICROWAVE EYE IN THE 262115Z SSMIS 37
GHZ PASS. THE INITIAL INTENSITY OF 140 KNOTS IS BASED ON EQUIVALENT
AND NEARLY CONCENTRIC DVORAK ESTIMATE FIXES OF T7.0 FROM PGTW AND
RJTD. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW
10-15 KNOT) RELATIVE EASTERLY VERTICAL WIND SHEAR (VWS) AND ROBUST
RADIAL OUTFLOW WITH A STRONG POLEWARD CHANNEL. SST AND OHC VALUES IN
THE PHILIPPINE SEA ARE ALSO VERY CONDUCIVE. THE CYCLONE IS TRACKING
ALONG THE SOUTHWEST PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. STY 31W IS FORECAST TO CONTINUE TRACKING WESTWARD THROUGH TAU
36. AFTERWARD, IT SHOULD GRADUALLY TURN MORE WEST-SOUTHWESTWARD AS
THE STR TO THE NORTHEAST BUILDS AND EXTENDS WESTWARD. THE FAVORABLE
ENVIRONMENT WILL PREVAIL AND EXTEND THE INTENSIFICATION TO A PEAK OF
145 KNOTS BY TAU 12. AFTERWARD, DIMINISHING OUTFLOW AS THE CYCLONE
MOVES FARTHER AWAY FROM THE TROUGH-ENHANCED POLEWARD OUTFLOW WILL
SLOWLY WEAKEN STY 31W DOWN TO 120 KNOTS BY TAU 72. NUMERICAL MODEL
GUIDANCE REMAINS IN GOOD AGREEMENT WITH GRADUAL SPREADING UP TO 340
NM BY TAU 72. NVGM AND CTCX - OUTLIERS ON THE RIGHT SIDE OF THE MODEL
ENVELOPE - CONTINUE TO PROMOTE AN EARLY RECURVATURE. THERE IS FAIR
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST THAT IS LAID
JUST LEFT OF CONSENSUS TO OFFSET THE UNLIKELY EARLY RECURVATURE.
   C. BEYOND TAU 72, STY YUTU WILL TRACK TOWARD THE NORTHERN TIP OF
LUZON ON A MORE WEST-NORTHWESTWARD TRAJECTORY AS THE STR WEAKENS IN
RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH AND BY TAU 120 WILL BE
IN THE MIDDLE OF LUZON STRAIT. IN ADDITION TO THE DIMINISHED OUTFLOW,
INCREASING VWS AND LAND INTERACTION WILL WEAKEN THE SYSTEM AT A
FASTER RATE, DOWN TO 90 KNOTS BY TAU 120. THERE IS SIGNIFICANT
SPREADING IN THE NUMERICAL MODELS - OVER 880 NM AT TAU 120. CTCX AND
NVGM ARE THE EXTREME EARLY RECURVE RIGHT-OF-TRACK OUTLIERS, AND JGSM
AND AFUM ARE ON THE FAR LEFT WITH A STRAIGHT WESTWARD AND LATE
RECURVE SOLUTION. IN VIEW OF THIS, LOW CONFIDENCE IN THE EXTENDED
PORTION OF THE JTWC FORECAST TRACK REMAINS.//
NNNN
NNNN