WDPN31 PGTW 031500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W WARNING 
NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 031200Z6 TO 061200Z9 SEP 01.
   A. TROPICAL DEPRESSION (TD) 19W, LOCATED APPROXIMATELY 525 NM 
EAST OF THE NORTHERN MARIANA ISLANDS, HAS TRACKED WESTWARD AT 07 
KNOTS DURING THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 
031130Z8 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED 
ON CURRENT SATELLITE INTENSITY ESTIMATES OF 25 TO 30 KNOTS. ENHANCED 
I/R DEPICTS DEEP CONVECTION BUILDING OVER THE LOW-LEVEL CIRCULATION 
CENTER. WATER VAPOR IMAGERY REVEALS A STRONG MID/UPPER LEVEL RIDGE 
TO THE NORTH OF THE SYSTEM.
   B. LOW/MID LEVEL HIGH HEIGHT CENTER SITUATED BETWEEN IWO JIMA AND 
OKINAWA IS FORECAST TO WEAKEN AND RETROGRADE NEAR THE 36 HOUR PERIOD 
AS A BAROCLINIC LOW DEVELOPS OFF OF HONSHU. THIS SHOULD CAUSE TD 19W 
TO TRACK IN A MORE NORTHWESTWARD MOTION WITHIN THE ENHANCED WEAKNESS 
AFTER AN INITIAL WEST-NORTHWESTWARD MOVEMENT. THE DYNAMICAL MODELS 
(UKMET-O GRID, JMA GLOBAL, NOGAPS, AND COAMPS) AND THE BETA 
ADVECTION MODELS (BAMS) ARE IN AGREEMENT WITH THIS SCENARIO. ITS 
INTERESTING TO NOTE THAT THE BAMS 24 HOUR TREND HAS BEEN REVEALING A 
MORE POLEWARD BIAS. THE OFFICIAL FORECAST IS BASED ON PERSISTENCE, 
THE DYNAMICAL CONSENSUS AND THE BAMS. 
   C. TD 19W IS EXPECTED TO INTENSIFY AT A CLIMATOLOGICAL RATE 
THROUGH THE FORECAST PERIOD AS THE SYSTEM MOVES TOWARD A COL BETWEEN 
BRANCHES OF THE SUBTROPICAL RIDGE.
   D. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE 
SIZE SYSTEM.  
FORECAST TEAM: ROBERTS/BALDINGER/HARRISON//