WDPN31 PGTW 110300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W (YAGI) WARNING NR 11// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 03W (YAGI), LOCATED APPROXIMATELY 321 NM WESTWARD OF CHICHI JIMA, HAS TRACKED NORTHWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TIGHTLY-CURVED BANDING WRAPPING INTO A WELL-DEFINED (BUT PARTIALLY- EXPOSED) LOW-LEVEL CIRCULATION CENTER (LLCC). MSI ALSO SHOWS A WEAK BAROCLINIC ZONE (BAIU BOUNDARY) POSITIONED SOUTH OF JAPAN, WHICH IS ORIENTED EAST-WEST NEAR 32 NORTH LATITUDE. A 102346Z SSMIS 37 GHZ IMAGE DEPICTS A DEFINED LOW-LEVEL CENTER WITH THE BULK OF DEEP CONVECTION LOCATED OVER THE EASTERN SEMI-CIRCLE. THIS IMAGE ALSO INDICATES A SLIGHT TILT TO THE SYSTEM WITH THE UPPER-LEVEL CENTER DISPLACED ABOUT 20 NM EAST OF THE LOW-LEVEL CENTER DUE TO NORTHWESTERLY VERTICAL WIND SHEAR (VWS). OVERALL, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THE MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS BASED ON AN AVERAGE OF DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 45 TO 65 KNOTS FROM PGTW AND KNES. ANIMATED WATER VAPOR SATELLITE IMAGERY SHOWS AN UPPER LEVEL TROUGH IMPINGING ON THE WESTERN PERIPHERY OF THE SYSTEM; HOWEVER, ROBUST POLEWARD OUTFLOW INTO TWO MID-LATITUDE TROUGHS TO THE NORTH AND NORTHEAST AND STRONG EQUATORWARD OUTFLOW ENHANCED BY A LARGE TUTT CELL IS OFFSETTING THE NEGATIVE IMPACT OF INCREASING VWS INDUCED BY THE APPROACHING TROUGH. TS 03W IS TRACKING ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL STEERING RIDGE. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING. B. TS 03W WILL CONTINUE TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF THE CURRENT STEERING RIDGE OVER THE NEXT 24 HOURS. PASSAGE OVER COOLER WATER, INTERACTION WITH THE BAIU BOUNDARY AND A FURTHER INCREASE IN VWS WILL INDUCE STEADY DISSIPATION DURING THIS PERIOD, CAUSING THE SYSTEM TO TRACK WITH THE LOW TO MID-LEVEL STEERING FLOW AFTER TAU 24. SOME SPREAD REMAINS IN THE DYNAMIC MODEL GUIDANCE DUE TO SLIGHT DISAGREEMENT ON THE ORIENTATION OF A STEERING RIDGE BUILDING TO THE WEST OF THE WEAKENING TS 03W IN THE EXTENDED TAUS. HOWEVER, BECAUSE DISAGREEMENT AMONG THE MODEL TRACKS THROUGH TAU 72 IS SMALL, THE OFFICIAL FORECAST TRACK IS LAID CLOSE TO MULTI- MODEL CONSENSUS WITH HIGH CONFIDENCE.// NNNN