Tropical Storm KOPPU Advisory mar, 13.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (TWENTYFOUR)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 24W (TWENTYFOUR), LOCATED APPROXIMATELY
155 NM NORTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 22
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS THE SYSTEM HAS DEEPENED AS FORMATIVE BANDS,
ALBEIT STILL FRAGMENTED, WRAPPED TIGHTER INTO A BROAD LOW LEVEL
CIRCULATION CENTER (LLCC) THAT IS OBSCURED BY A CENTRAL DENSE
OVERCAST FEATURE. THE SAME ANIMATION INDICATES THE MAIN BULK OF THE
CONVECTION IS SHEARED WESTWARD OF THE LLCC. THE INITIAL POSITION IS
BASED ON THE MSI LOOP AND EXTRAPOLATED FROM SURFACE OBSERVATIONS FROM
GUAM AND SAIPAN WITH LOW CONFIDENCE. THE INITIAL INTENSITY OF 25
KNOTS IS BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM
PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS
SOUTH OF THE RIDGE AXIS IN AN AREA OF MODERATE 20-KNOT VERTICAL WIND
SHEAR (VWS). HOWEVER, THE VWS IS EASILY OFFSET BY A NEAR-RADIAL
OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING BULLETIN AND SETS THE
FORECAST PHILOSOPHY.
   B. TD 24W WILL TRACK WESTWARD UNDER THE INFLUENCE OF THE STR
THROUGHOUT THE FORECAST PERIOD. AS IT TRAVERSES THE WARM PHILIPPINE
SEA (WITH SSTS 29-31 CELSIUS), THE VWS IS EXPECTED TO RELAX. THIS
COUPLED WITH A CONTINUED VIGOROUS OUTFLOW WILL PROMOTE STEADY
INTENSIFICATION, REACHING TYPHOON STRENGTH BY TAU 72.
   C. BEYOND TAU 72, THE SYSTEM WILL APPROACH NORTHERN LUZON,
PHILIPPINES. ENHANCED OUTFLOW, IN ADDITION TO THE AFOREMENTIONED
FAVORABLE CONDITIONS, WILL PROMOTE A RAPID INTENSIFICATION - REACHING
115 KNOTS, POSSIBLY STRONGER, BY END OF FORECAST. THE AVAILABLE
DYNAMIC MODELS ARE IN GOOD AGREEMENT WITH SOME BIFURCATION TOWARDS
THE END OF THE FORECAST. HOWEVER, GIVEN THE UNCERTAINTY IN THE
INITIAL POSITION AND STORM MOTION, THERE IS OVERALL LOW CONFIDENCE TO
THE INITIAL JTWC FORECAST TRACK.//
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