Tropical Storm KAI-TAK Advisory Mon Aug 13

MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (KAI-TAK) WARNING
NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 14W (KAI-TAK), LOCATED APPROXIMATELY 290 NM
EAST-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-SOUTHWESTWARD
AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION HAS FURTHER DEEPENED
AS A MESOSCALE ANTICYCLONE DEVELOPED OVER THE SYSTEM. THE INITIAL
POSITION IS EXTRAPOLATED FROM A 131141Z SSMI-S MICROWAVE IMAGE.
INITIAL INTENSITY IS BASED ON THE HIGH END OF 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 OVER THE NEXT 12 HOURS
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.
   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 OUTLIER BUT ECMWF AND NOGAPS DEPICT AN
UNLIKELY POLEWARD TRACK THAT WOULD CARRY THE STORM INTO THE CURRENT
STEERING RIDGE. THIS 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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