Tropical Storm YUTU Advisory 10月28日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (YUTU) WARNING NR
26//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 31W (YUTU), LOCATED APPROXIMATELY 616 NM
EAST-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 11
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED AN ENLARGING 36-NM
RAGGED EYE AS COMPACT RAIN BANDS CONTINUE TO WRAP TIGHTLY TOWARD THE
CENTRAL CONVECTION WITH VERY COLD CONVECTIVE TOPS (LESS THAN -80C)
ESPECIALLY ALONG THE SOUTHWEST QUADRANT. THE INITIAL POSITION IS
BASED ON THE EYE FEATURE IN THE EIR LOOP WITH HIGH CONFIDENCE. THE
INITIAL INTENSITY OF 135 KNOTS IS AVERAGED FROM NEAR CONCENTRIC
DVORAK FIXES FROM PGTW (T6.5), RJTD (T7.0), AND CIMS (T7.1). UPPER
LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LOW (10-15 KNOT)
RELATIVE EASTERLY VERTICAL WIND SHEAR (VWS) AND ROBUST RADIAL OUTFLOW
WITH A STRONG POLEWARD CHANNEL. ADDITIONALLY, ALONG-TRACK SST AND OHC
VALUES IN THE PHILIPPINE SEA ARE PERENNIALLY CONDUCIVE. THE CYCLONE
IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF AN EAST-WEST ORIENTED
SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. STY 31W WILL TRACK WESTWARD THEN WEST-SOUTHWESTWARD TOWARD
LUZON AS THE STR BUILDS, MAKING LANDFALL NEAR PALANAN, ISABELA AROUND
TAU 54, DRAG QUICKLY ACROSS LUZON AND EXIT INTO THE SOUTH CHINA SEA
(SCS) BY TAU 72. THE SYSTEM WILL INITIALLY MAINTAIN ITS CURRENT
INTENSITY THEN SLOWLY WEAKEN TO 125 KNOTS BY TAU 36 AS OUTFLOW
DIMINISHES. HOWEVER, BY TAU 48, PRIOR TO LANDFALL, THE CYCLONE IS
EXPECTED TO RE-INTENSIFY TO 130 KNOTS AS POLEWARD OUTFLOW INCREASES
AHEAD OF A MID-LATITUDE SHORTWAVE TROUGH APPROACHING FROM THE
NORTHWEST. AFTERWARD, LAND INTERACTION WITH LUZON AND INCREASING VWS
WILL REDUCE THE SYSTEM DOWN TO 80 KNOTS AS IT EXITS INTO THE SCS.
NUMERICAL GUIDANCE IS IN GOOD AGREEMENT WITH MINIMAL SPREADING TO 180
NM AT TAU 72, LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC
FORECAST THAT IS LAID VERY CLOSE TO CONSENSUS. CTCX CONTINUES TO BE
THE RIGHT OF TRACK OUTLIER AND JGSM ON THE LEFT.
   C. BEYOND TAU 72, THE AFOREMENTIONED MID-LATITUDE TROUGH WILL
WEAKEN THE STR AND ALLOW STY 31W TO TURN NORTHWARD. ENVIRONMENTAL
CONDITIONS WILL BE MARGINALLY FAVORABLE AS THE CYCLONE STARTS TO
RECURVE AROUND THE STR AXIS AND SOME INTENSIFICATION IS ANTICIPATED
ONCE THE CYCLONE MOVES BACK OVER WATER, TEMPERED ONLY BY A COLD SURGE
EVENT IN THE SCS. ALL MEMBERS OF THE CONSENSUS ARE NOW DEPICTING
RECURVATURE IN VARYING DEGREES. THE SPREAD BETWEEN THE LEFTMOST
(JGSM) AND RIGHTMOST (CTCX) MEMBERS HAS DECREASED TO 480 NM AT TAU
120, LENDING FAIR CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC
FORECAST TRACK THAT IS ALSO LAID CLOSE TO CONSENSUS.//
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