WDPN31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 03W (THREE) 
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 03W (THREE), LOCATED APPROXIMATELY 308 
NM SOUTH-SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST-
NORTHWESTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FLARING CONVECTION 
THAT IS STARTING TO BUILD OVER AN ILL-DEFINED AND BROAD LOW LEVEL 
CIRCULATION CENTER (LLCC). A 271950Z SSMIS 37 GHZ MICROWAVE IMAGE 
REVEALS A SLIGHT INCREASE IN THE CONSOLIDATION OF THE LOW-LEVEL 
STRUCTURE WHILE THE BULK OF THE CONVECTION CONTINUES TO BE CONTAINED 
TO THE NORTH WHILE THERE HAS BEEN AN INCREASE IN CONVECTION ALONG 
THE SOUTHWESTERN PERIPHERY THAT HAS STARTED TO WRAP INTO THE LLCC. 
THE INITIAL POSITION IS BASED UPON THE MSI ANIMATION WITH LOW 
CONFIDENCE AS THE FLARING CONVECTION IS OBSCURING THE LLCC AND 
AGENCY POSITION FIXES ARE WIDELY SPREAD. THE INITIAL INTENSITY IS 
ASSESSED AT 25 KNOTS BASED UPON THE BROAD ORGANIZATION OF THE SYSTEM 
AND DVORAK INTENSITY ESTIMATES OF THE SAME VALUE FROM PGTW AND KNES. 
UPPER-LEVEL ANALYSIS REVEALS A MARGINAL ENVIRONMENT AS VIGOROUS 
POLEWARD OUTFLOW IS BEING OFFSET BY MODERATE (15 TO 20 KNOTS) 
VERTICAL WIND SHEAR (VWS). TD 03W IS CURRENTLY IN A WEAK STEERING 
ENVIRONMENT AND IS TRACKING SLIGHTLY ERRATIC AS THE SYSTEM IS 
BETWEEN TWO LOW- TO MID-LEVEL SUBTROPICAL RIDGES (STR) TO THE 
NORTHEAST AND NORTHWEST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST 
PHILOSOPHY.
   B. TD 03W IS EXPECTED TO STAY IN THIS WEAK STEERING ENVIRONMENT 
BETWEEN THE TWO STEERING RIDGES FOR THE NEXT TWO DAYS WITH A HIGH 
POSSIBILITY OF QUASI-STATIONARY AND ERRATIC MOTION. AFTER TAU 48, 
THE STR TO THE NORTHEAST IS EXPECTED TO AMPLIFY AND BECOME THE 
DOMINANT STEERING INFLUENCE. THIS WILL DRIVE TD 03W ON A POLEWARD 
TRACK AND WILL INCREASE TRACK SPEEDS. THE SYSTEM IS EXPECTED TO 
SLOWLY INTENSIFY THROUGH THE NEXT 72 HOURS, REACHING A PEAK OF 50 
KNOTS, AS MODELS INDICATE A SLIGHT RELAXATION OF THE VWS AS TD 03W 
GAINS LATITUDE. NUMERIC MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT 
WITH THE WEAK STEERING ENVIRONMENT AS THE TRACKERS KEEP THE SYSTEM 
VERY SLOW MOVING THROUGH THE NEXT 48 HOURS ALTHOUGH WITH VARYING 
TRAJECTORIES DUE TO THE POORLY DEFINED STEERING.
   C. IN THE EXTENDED PERIOD, TD 03W IS EXPECTED TO FURTHER 
ACCELERATE POLEWARD AS IT TRACKS ALONG THE PERIPHERY OF THE STR AND 
WILL BEGIN TO TAKE A NORTHEASTWARD TRACK AS IT APPROACHES THE MID-
LATITUDE WESTERLIES BY TAU 120. THE SYSTEM IS EXPECTED TO WEAKEN 
AFTER TAU 72 AS INCREASING VWS FROM THE WESTERLIES WILL START TO 
HAMPER THE SYSTEM. EXTRA-TROPICAL TRANSITION IS FORECAST TO BEGIN AT 
TAU 120 AS THE SYSTEM APPROACHES THE WESTERLIES AND SEA SURFACE 
TEMPERATURES START TO DECREASE. NUMERIC MODEL GUIDANCE REMAINS IN 
GOOD AGREEMENT WITH THE OVERALL FORECAST SCENARIO IN THE EXTENDED 
TAUS ALTHOUGH MODELS ARE WIDELY SPREAD DUE TO THE WEAK STEERING IN 
THE EARLY PORTION OF THE FORECAST. THE JTWC FORECAST TRACK IS 
POSITIONED CLOSE TO MULTI-MODEL CONSENSUS DUE TO THIS SPREAD. 
OVERALL, CONSIDERING THE WEAK STEERING ENVIRONMENT IN THE EARLY TAUS 
AND THE POOR CONFIDENCE IN THE INITIAL POSITION, THERE IS LOW 
CONFIDENCE IN THE FORECAST.//
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