Tropical Storm HAIKUI Advisory Tue Aug 07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (HAIKUI) WARNING NR 20//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 12W (HAIKUI), LOCATED APPROXIMATELY 225 NM
SOUTH-SOUTHEAST OF SHANGHAI, CHINA, HAS TRACKED NORTHWESTWARD AT 08
KNOTS OVER THE PAST SIX HOURS.  ANIMATED ENHANCE INFRARED SATELLITE
IMAGERY SHOWS A RAGGED ELONGATED EYE WITH CONVECTIVE BANDS BECOMING
MORE SHALLOW AND LOOSE. THE CURRENT POSITION IS BASED ON THE ABOVE
ANIMATION AND SUPPORTED BY A SEMI-CIRCLE LOW LEVEL FEATURE ON A
071116Z 37GHZ SSMI-S MICROWAVE IMAGE. THE CURRENT INTENSITY IS
AVERAGED FROM DVORAK ESTIMATES FROM PGTW AND RJTD. UPPER-LEVEL
ANALYSIS INDICATES THE CYCLONE IS JUST TO THE WEST OF AN ANTICYCLONE
IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL WIND SHEAR. IT IS BEING
STEERED BY A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 12W IS FORECAST TO MAINTAIN ITS CURRENT TRACK AND MAKE
LANDFALL SOUTH OF ZHOUSHAN, CHINA, JUST BEFORE TAU 12. IT WILL THEN
RAPIDLY WEAKEN AND DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE OVER
LAND BY TAU 36 DUE TO FRICTIONAL EFFECTS. A SHORTWAVE TROUGH MOVING
THROUGH CENTRAL CHINA IS FORECAST TO INTERACT WITH THE SYSTEM AND MAY
CAUSE AN ABRUPT TURN TO THE NORTHEAST JUST PRIOR TO OR SHORTLY AFTER
DISSIPATION. THERE REMAINS A SMALL PROBABILITY FOR REGENERATION
AFTER THE REMNANTS OF TY 12W TRACK BACK OVER THE EAST CHINA SEA,
HOWEVER, INCREASED SHEAR DUE TO THE TROUGH AND LOWER SEA SURFACE
TEMPERATURES MAKE THIS AN UNLIKELY SCENARIO. THE MODELS ARE IN TIGHT
AGREEMENT THROUGH THE END OF THE FORECAST. AS A RESULT, THERE IS
HIGH CONFIDENCE IN THE FORECAST TRACK.    //
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