Tropical Storm MERBOK Advisory Mon Jun 12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MERBOK)
WARNING NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TROPICAL STORM 04W (MERBOK), LOCATED APPROXIMATELY 21 NM
SOUTHEAST OF HONG KONG, HAS TRACKED NORTHWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY
SHOWS FLARING CONVECTION LOCATED TO THE SOUTH OF THE LOW LEVEL
CIRCULATION CENTER (LLCC). THE CONVECTION IS DISPLACED DUE TO
INCREASING VERTICAL WIND SHEAR IMPACTING THE SYSTEM. THE INITIAL
POSITION IS BASED ON ANIMATED IR IMAGERY AND A 121038Z F17 SSMIS
37GHZ MICROWAVE IMAGE THAT SHOWS A DISORGANIZED LOWER LEVEL
CONVECTIVE STRUCTURE AS THE SYSTEM BEGINS TO INTERACT WITH LAND. THE
INITIAL INTENSITY OF 45 KNOTS IS BASED ON MULTIAGENCY DVORAK
ESTIMATES OF T3.0 AND A SATCON ESTIMATE OF 45 KNOTS. ENVIRONMENTAL
ANALYSIS SHOWS DETERIORATING UPPER LEVEL CONDITIONS AS TS 04W IS NOW
IN AN AREA OF MODERATE TO UNFAVORABLE VERTICAL WIND SHEAR (20-25
KNOTS) AND THE EQUATORWARD OUTFLOW CHANNEL HAS BECOME LESS
ORGANIZED. TS MERBOK IS CURRENTLY TRACKING NORTHWEST HOWEVER, THE
TRACK IS TURNING TO THE EAST DUE TO THE SYSTEM ROUNDING THE
NORTHWEST PERIPHERY OF A SUBTROPICAL STEERING RIDGE (STR).
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
    B. TS 04W IS FORECAST TO MAKE LANDFALL BEFORE TAU 12 TO THE
EAST OF HONG KONG. ONCE THE SYSTEM MAKES LANDFALL IT WILL RECURVE TO
THE NORTHEAST AS IT CONTINUES TO ROUND THE NORTHWESTERN PERIPHERY OF
THE STR. THE SYSTEM’S CURRENT PROXIMITY TO LAND WILL PREVENT FURTHER
INTENSIFICATION PRIOR TO LANDFALL. THE RUGGED TERRAIN OF SOUTHEAST
CHINA WILL RAPIDLY DETERIORATE THE SYSTEM POST LANDFALL RESULTING IN
COMPLETE DISSIPATION BY TAU 36. AFTER TAU 36 THE REMNANTS OF TS
MERBOK WILL MOVE INTO THE EAST CHINA SEA WITH A LIMITED POSSIBILITY
OF RE-INTENSIFICATION. THE DYNAMIC MODEL GUIDANCE REMAINS IN STRONG
AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.//
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