Tropical Storm YUTU Advisory 27 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (YUTU) WARNING NR
22//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON 31W (YUTU), LOCATED APPROXIMATELY 894 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD
AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED A SHARPLY-OUTLINED
30-NM EYE AS RAIN BANDS WRAPPED EVEN TIGHTER INTO THE CENTRAL
CONVECTION THAT CONTINUES TO DEEPEN, AS EVIDENCED BY VERY COLD CLOUD
TOPS (-82 CELSIUS). THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF 140 KNOTS IS
BASED ON THE DVORAK ESTIMATES OF T7.0 FROM PGTW AND T7.2 FROM CIMMS.
UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW 10-15
KNOT) EASTERLY VERTICAL WIND SHEAR (VWS) AND ROBUST 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 TOWARD A
BREAK CAUSED BY AN APPROACHING MID-LATITUDE SHORTWAVE TROUGH DIGGING
INTO THE YELLOW SEA.
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 WEST-NORTHWESTWARD
TOWARD THE BREAK IN THE STR THROUGH TAU 36. AFTERWARD, IT SHOULD
GRADUALLY TURN MORE WESTWARD AS THE AFOREMENTIONED SHORTWAVE TROUGH
PROPAGATES EASTWARD AND THE STR TO THE NORTHEAST RE-BUILDS AND
EXTENDS WESTWARD. THE FAVORABLE ENVIRONMENT WILL PREVAIL AND EXTEND
THE INTENSIFICATION TO A PEAK OF 145 KNOTS AT TAUS 12-24. AFTERWARD,
DIMINISHING OUTFLOW AS THE CYCLONE APPROACHES THE SHORTWAVE TROUGH
WILL SLOWLY WEAKEN STY 31W DOWN TO 120 KNOTS BY TAU 72. NUMERICAL
MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH MINIMAL SPREADING UP TO
230 NM BY TAU 72. NVGM AND CTCX, ON THE RIGHT SIDE OF THE 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 INITIALLY TRACK TOWARD NORTHERN
LUZON ON A MORE WEST-SOUTHWESTWARD TRAJECTORY UNDER A REINVIGORATED
STR TO THE NORTHEAST. HOWEVER, AFTER TAU 96, IT WILL TRACK MORE
WEST-NORTHWESTWARD, CLIPPING THE NORTHEAST TIP OF LUZON AS THE STR
ONCE AGAIN WEAKENS WITH THE APPROACH OF YET ANOTHER MID-LATITUDE
TROUGH. IN ADDITION TO THE DIMINISHED OUTFLOW, INCREASING VWS AND
LAND INTERACTION WILL WEAKEN THE SYSTEM AT A FASTER RATE, DOWN TO 95
KNOTS AS IT ENTERS THE SOUTH CHINA SEA. THERE IS SIGNIFICANT
SPREADING IN THE NUMERICAL MODELS - OVER 800 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 TRACK
SOLUTION. IN VIEW OF THIS, LOW CONFIDENCE IN THE EXTENDED PORTION OF
THE JTWC FORECAST TRACK REMAINS.//
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