Tropical Storm KAI-TAK Advisory Tu, 14-08

MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (KAI-TAK) WARNING
NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 14W (KAI-TAK), LOCATED APPROXIMATELY 345
NM EAST-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13
KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS A BROAD, PARTIALLY-EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION PERSISTING ALONG THE
WESTERN PERIPHERY. THE INITIAL INTENSITY IS BASED ON THE ABOVE
ANIMATION AND FROM A 130511Z AMSU-B MICROWAVE IMAGE WITH FAIR
CONFIDENCE. THE INITIAL INTENSITY IS SUPPORTED BY DVORAK ESTIMATES
FROM PGTW, RJTD, AND KNES. TS 14W LIES EQUATORWARD OF AN UPPER-LEVEL
RIDGE AXIS IN AN AREA OF LOW TO MODERATE (10-15 KNOT) VERTICAL WIND
SHEAR (VWS) AND STRONG EQUATORWARD OUTFLOW. POLEWARD OUTFLOW TOWARD
A WEAK UPPER LEVEL LOW TO THE NORTHEAST HAS ALSO PERSISTED. THE
CYCLONE CONTINUES TO TRACK WESTWARD ALONG THE SOUTHERN PERIPHERY OF
A DEEP-LAYERED SUBTROPICAL RIDGE.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 14W IS EXPECTED TO TURN NORTHWESTWARD AFTER TAU 12 IN
RESPONSE TO A WEAKNESS IN THE SUBTROPICAL STEERING RIDGE INDUCED BY
A SHORTWAVE TROUGH APPROACHING FROM THE NORTHWEST AND MOVING INTO
THE EAST CHINA SEA. MODERATE VWS WILL TEMPER IMPROVED UPPER-LEVEL
OUTFLOW TO HOLD INTENSIFICATION TO A SLOW RATE EARLY IN THE FORECAST
PERIOD. HOWEVER, SHEAR IS EXPECTED TO RELAX AFTER TAU 36 AS THE
SYSTEM APPROACHES THE UPPER-LEVEL RIDGE AXIS AND THE CYCLONE BEGINS
TO DEVELOP A MESOSCALE ANTICYCLONE ALOFT.
   C. AFTER TAU 72, TS KAI-TAK IS EXPECTED TO CONTINUE TRACKING
ALONG THE SOUTHERN PERIPHERY OF THE CURRENT STEERING RIDGE, MAKING
LANDFALL BEFORE TAU 96. DECREASING OCEAN HEAT CONTENT AND
INCREASINGLY RESTRICTED POLEWARD OUTFLOW SHOULD CAUSE THE SYSTEM TO
WEAKEN SLIGHTLY PRIOR TO LANDFALL. TS 14W WILL DISSIPATE RAPIDLY
AFTER LANDFALL. THE NUMERICAL MODELS ARE IN GOOD AGREEMENT. WBAR
REMAINS THE LEFT OUTLIER BUT GFDN DEPICTS AN UNREALISTIC POLEWARD
TRACK THAT WOULD CARRY THE STORM INTO THE CURRENT STEERING RIDGE.
THE CURRENT FORECAST LIES SLIGHTLY EQUATORWARD OF THE NUMERICAL
MODEL CONSENSUS, CONSISTENT WITH CURRENT ANALYSIS AND PROGNOSIS OF
THE STEERING PATTERN. GIVEN THE INCREASING AGREEMENT OF THE
OBJECTIVE AID PACKAGE, TRACK FORECAST CONFIDENCE IS HIGH.    //
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