WTDN31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 29W 
(TWENTYNINE) WARNING NR 03//
RMKS//
/1. FOR METEOROLOGISTS
 2. 6-HOUR SUMMARY AND ANALYSIS:
    TROPICAL DEPRESSION 29W (TWENTYNINE), LOCATED 
APPROXIMATELY 634 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED
WESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED 
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE OVERALL
CONVECTION ASSOCIATED WITH THE CONSOLIDATING LOW-LEVEL 
CIRCULATION CENTER (LLCC), HAS SLIGHTLY IMPROVED AS FORMATIVE
BANDS HAVE DEEPENED AND ARE WRAPPING TIGHTER INTO THE LLCC.
THE INITIAL POSITION IS BASED ON THE EIR ANIMATION AND 
EXTRAPOLATED FROM A 291111Z SSMIS MICROWAVE IMAGE WITH FAIR 
CONFIDENCE. THE INITIAL INTENSITY IS HEDGED ON THE HIGH END 
OF DVORAK ESTIMATES FROM PGTW AND KNES RANGING FROM 25 TO 30 
KNOTS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST SOUTH
OF THE RIDGE AXIS IN AN AREA OF LOW TO MODERATE (10-15 KNOT) 
VERTICAL WIND SHEAR AND GOOD POLEWARD OUTFLOW. THE CYCLONE IS 
TRACKING ALONG THE SOUTHERN PERIPHERY OF A WELL-ESTABLISHED 
SUBTROPICAL RIDGE (STR) TO THE NORTH.
 3. FORECAST REASONING:
    A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE, BUT TRACK SPEEDS HAVE SLIGHTLY 
SLOWED AND ARE IN BETTER AGREEMENT WITH THE 29/06Z NAVGEM AND 
GFS MODEL FIELDS.
    B. TD 29W IS FORECAST TO TRACK GENERALLY WESTWARD, STEERED
BY THE STR, THROUGHOUT ITS LIFESPAN. FAVORABLE UPPER LEVEL 
CONDITIONS, IN ADDITION TO PERENNIALLY WARM SEA SURFACE 
TEMPERATURES IN THE PHILIPPINE SEA WILL ENSURE STEADY 
INTENSIFICATION THROUGH TAU 36. BETWEEN TAU 36 AND TAU 48 THE 
SYSTEM SHOULD REACH TYPHOON STRENGTH. BY TAU 48 TD 29W WILL BE
TRACKING OVER THE ISLAND OF LUZON AND WILL SLIGHTLY WEAKEN DUE
TO FRICTIONAL EFFECTS OF LAND. ONCE THE SYSTEM EMERGES IN THE 
SOUTH CHINA SEA IT WILL ONCE AGAIN BEGIN TO INTENSIFY AND 
REACH A PEAK INTENSITY OF 70 KNOTS BY TAU 72.
    C. BEYOND TAU 72, THE SYSTEM WILL CROSS HAINAN, CHINA, AND
THE GULF OF TONKIN BEFORE MAKING LANDFALL NEAR HANOI, VIETNAM,
BY TAU 12O. INTERACTION WITH THE TOPOGRAPHY OF HAINAN AND 
VIETNAM WILL GRADUALLY ERODE THE SYSTEM. THOUGH NUMERIC MODEL 
GUIDANCE IS LIMITED AT THIS TIME, THE OBJECTIVE AIDS THAT ARE
AVAILABLE ARE IN FAIRLY TIGHT AGREEMENT THROUGH TAU 48, BUT 
BEGIN DIVERGE IN POSITION AND TRACK SPEED THEREAFTER. GIVEN 
THE FORMATIVE STAGE OF THE SYSTEM AND THE INCREASED UNCERTAINTY
IN THE EXTENDED TAUS, THERE IS LOW CONFIDENCE IN THE JTWC 
FORECAST.//
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