WDPN31 PGTW 121500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W/
WARNING NR04//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 121200Z6 TO 151200Z9 FEB 2004.
   A. TROPICAL DEPRESSION (TD) 01W, LOCATED APPROXIMATELY 240 NM
WEST OF AGANA, GUAM, HAS TRACKED WEST-NORTHWESTWARD
AT 12 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS
BASED ON 121130Z8 ENHANCED INFRARED SATELLITE IMAGERY. WARNING
INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES
OF 25, 30, AND 35 KNOTS. RECENT ANIMATED INFRARED SATELLITE
IMAGERY INDICATES THE DEEP CONVECTION HAS WEAKENED OVER THE
LOW LEVEL CIRCULATION CENTER (LLCC). UPPER LEVEL ANALYSIS
SHOWS MODERATE POLEWARD DIFFLUENCE AND WEAK VERTICAL WIND
SHEAR.
   B. TD 01W IS FORECAST TO CONTINUE TO TRACK NORTHWESTWARD ALONG
THE SOUTHWEST PERIPHERY OF THE MID-LEVEL STEERING RIDGE. THE
AVAILABLE AIDS CONSISTING OF THE SHALLOW AND MEDIUM BETA ADVECTION
MODELS, AND WBAR ARE IN GOOD AGREEMENT WITH THIS SCENARIO. THE
AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, UKMET (EGRR), NCEP GFS,
AND COAMPS ARE IN GOOD AGREEMENT THROUGH TAU 36 AND THEN PURSUE A
MORE WESTWARD TRACK AS A RESULT OF INTERACTION WITH A LOW PRESSURE
WEAKNESS FORMING OFF THE COAST OF MINDINAO. THIS FORECAST IS BASED
ON PERSISTENCE THROUGH TAU 36 AND THEN THE BETA ADVECTION MODELS.
   C. TD 01W WILL CONTINUE TO INTENSIFY AT LESS THAN A CLIMATOLOGICAL
RATE FOR THE FIRST 36 HOURS OF THE FORECAST PERIOD AS THE
ENVIRONMENT IS EXPECTED TO REMAIN FAVORABLE WITH WEAK TO MODERATE
VERTICAL SHEAR AND GOOD DIFFLUENCE ALOFT. AFTER 48 HOURS, 
INCREASING VERTICAL SHEAR, COOLER SEA SURFACE TEMPERATURES, AND
ENTRAINMENT OF DRY AIR IS EXPECTED TO WEAKEN THE SYSTEM AS IT
APPROACHES AND TRACKS POLEWARD OF THE STEERING RIDGE AXIS.
   D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY 
FOR AN AVERAGE-SIZED SYSTEM.
FORECAST TEAM: MOHAMMED/ANDERSON//
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