Tropical Storm DUJUAN Advisory jue, 18-02

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 01W (ONE), LOCATED APPROXIMATELY 88 NM WEST-
SOUTHWEST OF KOROR, REPUBLIC OF PALAU, HAS TRACKED WESTWARD AT 12
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS FORMATIVE RAIN BANDS WITH FRAGMENTED DEEP CONVECTION
LOOSELY WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION (LLC). THE
INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON LOW CLOUD
TRACING IN THE MSI LOOP INTO THE OBSCURED LLC AND LINED UP WITH A
FORMATIVE LLC FEATURE IN THE 170447Z GCOM MICROWAVE IMAGE. THE
INITIAL INTENSITY OF 25KTS IS BASED ON THE DVORAK ESTIMATES OF
T1.5/25KTS FROM PGTW AND RJTD AND EXTRAPOLATED FROM THE WIND AND
PRESSURE OBSERVATION FROM KOROR, THAT SAW A 5MB DROP IN 24 HOURS TO
1003MB. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW (10-
15KT) EASTERLY RELATIVE VERTICAL WIND SHEAR, ROBUST WESTWARD AND
POLEWARD UPPER LEVEL OUTFLOW THAT IS PROVIDING AMPLE VENTILATION TO
THE CONVECTION, AND WARM (29-30C) ALONG-TRACK SST IN THE PHILIPPINE
SEA. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY FOR THIS SYSTEM.
   B. TD 01W IS WILL TRACK MORE NORTHWESTWARD FOR THE DURATION OF
THE FORECAST UNDER THE STEERING INFLUENCE OF THE STR TO THE
NORTHEAST. THE FAVORABLE ENVIRONMENT WILL PROMOTE STEADY
INTENSIFICATION TO A PEAK OF 55KTS BY TAU 72 AS THE SYSTEM
APPROACHES CENTRAL PHILIPPINES.
   C. BEYOND TAU 72, TD 01W WILL MAKE LANDFALL OVER LEYTE BY TAU 96
AND TRACK ACROSS THE PHILIPPINE ARCHIPELAGO, AND BY TAU 120, WILL BE
OVER THE ISLAND OF MINDORO, APPROXIMATELY 90NM SOUTH OF MANILA.
INTERACTION WITH THE ISLANDS WILL ERODE THE SYSTEM DOWN TO 30KTS BY
TAU 120. NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT AND EVENLY
SPREAD OUT; HOWEVER, DUE TO THE UNCERTAINTY IN THE INITIAL STORM
MOTION OF THIS DEVELOPING CYCLONE, THERE IS LOW CONFIDENCE IN THE
FIRST JTWC TRACK FORECAST ON THIS SYSTEM.//
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