MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (FOUR) WARNING NR 02// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION 04W (FOUR), LOCATED APPROXIMATELY 652 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON LOW-LEVEL BANDING EVIDENT IN RECENT MICROWAVE SATELLITE IMAGERY INCLUDING A 282145Z CORIOLIS PASS. THE INTENSITY OF 30 KNOTS IS SUPPORTED BY RECENT SUBJECTIVE DVORAK ESTIMATES OF T2.0 FROM PGTW AND KNES, AND IS CONSISTENT WITH LEVEL STRUCTURE EVIDENT IN SATELLITE DATA. TD 04W HAS TRACKED WEST-NORTHWESTWARD ALONG THE PERIPHERY OF A SUBTROPICAL STEERING RIDGE SITUATED TO THE NORTH AND EAST OVER THE PAST SIX HOURS. DEEP CONVECTION CONTINUES TO FLARE AND WANE OVER THE SOUTHWESTERN PORTION OF THE LOW LEVEL CIRCULATION AS THE SYSTEM EXPERIENCES PERSISTENT NORTHEASTERLY VERTICAL WIND SHEAR (VWS). THE SEA SURFACE TEMPERATURE IN VICINITY OF THE LLCC IS VERY SUPPORTIVE AT 29 TO 30 DEGREES CELSIUS. 3. FORECAST REASONING. A. EXTENDED RANGE FORECAST INTENSITIES HAVE BEEN REDUCED FROM THE PREVIOUS WARNING. HOWEVER, THERE IS NO MAJOR CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS WARNING. B. TD 04W IS EXPECTED TO TRACK NORTHWESTWARD IN THE NEAR TERM UNDER THE CONTINUED STEERING INFLUENCE OF THE SUBTROPICAL RIDGING TO THE NORTH AND EAST. VWS WILL PERSIST THROUGH TAU 72, LIMITING INTENSIFICATION TO A SLOW RATE DESPITE PASSAGE OVER VERY WARM WATER AN FAVORABLE SOUTHWESTWARD DIFFLUENCE ALOFT. NUMERICAL MODEL TRACK FORECAST GUIDANCE REMAINS SPLIT, WITH A GROUPING CONSISTING OF THE GEFS ENSEMBLE AND HWRF MODELS PREDICTING A TRACK TO THE SOUTH OF TAIWAN AND THE UKMET, NAVGEM AND ECMWF PREDICTING A TRACK FARTHER TO THE NORTH. THE CURRENT FORECAST IS CONSERVATIVELY CONSISTENT WITH THE PREVIOUS JTWC TRACK FORECAST AND CURRENT MULTI-MODEL CONSENSUS THROUGH TAU 72. THE EXACT TRACK WILL DEPEND ON THE AS YET UNCERTAIN ORIENTATION OF THE SUBTROPICAL STEERING RIDGE DURING THIS PERIOD. C. TD 04W IS EXPECTED TO BEGIN WEAKENING IN THE EXTENDED RANGE IN RESPONSE TO INCREASING VERTICAL WIND SHEAR AND POTENTIAL LAND INTERACTION. NUMERICAL MODEL TRACK FORECAST SPREAD IS PARTICULARLY PRONOUNCED IN THE EXTENDED RANGE. A FEW CONSENSUS MODELS DEPICT TD 04W TURNING WESTWARD AND INTERACTING WITH A DEVELOPING CIRCULATION IN THE NORTHERN SOUTH CHINA SEA, WHILE OTHER MODELS DEPICT TD 04W MAINTAINING A NORTHWESTWARD TRACK OR TURNING POLEWARD ALONG THE STEERING RIDGE PERIPHERY. THE CURRENT TRACK FORECAST IS WEIGHTED TOWARD THE NORTHWESTWARD AND POLEWARD TRACK GROUPING BASED ON EXPECTATIONS OF SLOW BUT SUFFICIENT NEAR TERM INTENSIFICATION. OVERALL, THERE IS LOW CONFIDENCE IN THE CURRENT JTWC TRACK FORECAST.// NNNN NNNN