WDPN32 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 12W (TWELVE) 
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 12W (TWELVE), LOCATED APPROXIMATELY 382 NM
SOUTH-SOUTHWESTWARD OF KADENA AB, HAS TRACKED SOUTHEASTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) INDICATES A CONSOLIDATING, YET SLIGHTLY ELONGATED, LOW-
LEVEL CIRCULATION CENTER (LLCC) WITH INCREASING DEEP CONVECTION 
AROUND THE WESTERN AND SOUTHERN PERIPHERIES OF THE SYSTEM. THIS IS 
ALSO EVIDENT IN A 170332Z TRMM 37GHZ MICROWAVE. THE INITIAL POSITION 
IS BASED ON THE MSI AND AFOREMENTIONED MICROWAVE IMAGE WITH FAIR TO 
LOW CONFIDENCE DUE TO THE ELONGATED NATURE OF THE LLCC. THE INITIAL 
INTENSITY HAS BEEN INCREASED TO 30 KNOTS WHICH IS SLIGHTLY HIGHER 
THAN DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES DUE TO THE 
CONSOLIDATING STRUCTURE OF THE SYSTEM. UPPER-LEVEL ANALYSIS 
INDICATES THE SYSTEM IS JUST NORTH OF THE SUBTROPICAL RIDGE (STR) 
AXIS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY GOOD EQUATORWARD 
OUTFLOW AND LOW TO MODERATE (05 TO 15 KNOTS) VERTICAL WIND SHEAR. TD 
12W IS CURRENTLY TRACKING ALONG THE LOW TO MID-LEVEL STEERING RIDGE 
SOUTH OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING.
   B. TD 12W IS EXPECTED TO TRACK WEST ALONG THE PERIPHERY OF THE 
STEERING RIDGE THROUGH THE NEXT 36 HOURS. AFTER TAU 36 THE STEERING 
INFLUENCES WILL BECOME WEAK AS THE SYSTEM WILL BE POSITIONED BETWEEN 
TWO STEERING RIDGES, THE CURRENT STEERING RIDGE TO THE SOUTH AND A 
BUILDING RIDGE NORTH OF THE SYSTEM. AFTER TAU 48, THE RIDGE TO THE 
NORTH IS EXPECTED TO BUILD AND ALONG WITH MOTION INDUCED BY DIRECT 
CYCLONE INTERACTION (DCI) WITH NEIGHBORING TD 13W, SHOULD DRIVE THE 
SYSTEM WEST. TD 12W IS FORECAST TO INTENSIFY AS FAVORABLE 
ENVIRONMENTAL CONDITIONS OF GOOD OUTFLOW AND LOW VWS ARE EXPECTED 
THROUGH THIS PORTION OF THE FORECAST PERIOD.  ALTHOUGH, THE 
PROXIMITY AND INTENSITY OF TD 13W COULD CREATE A LESS FAVORABLE 
ENVIRONMENT WHICH WOULD LEAD TO A LOWER INTENSITY FORECAST.
   C. TD 12W IS EXPECTED CONTINUE TO INTERACT WITH TD 13W IN THE 
EXTENDED TAUS, AND EVENTUALLY MERGE INTO EACH OTHER BY TAU 120. SLOW 
INTENSIFICATION IS EXPECTED TO CONTINUE AS THESE TWO SYSTEMS 
CONSOLIDATE AND REACH TYPHOON STRENGTH BY TAU 120. DYNAMIC MODEL 
GUIDANCE IS SPREAD THROUGH THE FORECAST PERIOD DUE TO THE PROXIMITY 
OF TD 13W, AND THE DCI, AS TWO DIFFERENT SCENARIOS HAVE BECOME 
CLEAR. SOME MODELS CONTINUE TO SHOW THE CONTINUED DCI WHILE SOME 
SEEM TO INDICATE THAT TD 12W WILL BECOME THE DOMINANT CIRCULATION IN 
THIS SCENARIO AND CALL FOR TD 13W TO WEAKEN AS TD 12W CREATES AN 
UNFAVORABLE UPPER-LEVEL ENVIRONMENT. THERE IS LOW CONFIDENCE IN THE 
FORECAST DUE TO THIS.//
NNNN