WDPN33 PGTW 181500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FRANCISCO) WARNING NR 11// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 26W (FRANCISCO), LOCATED APPROXIMATELY 201 NM WEST- NORTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) INDICATES AN EXAGGERATED NORTHWARD WOBBLE HAS OCCURRED OVER THE PAST FEW HOURS, BUT WITH THE EYE AGAIN HEADED ON A MORE NORTHWESTERLY TRACK IN THE LAST FEW FRAMES OF THE IMAGERY. THE SYSTEM ITSELF HAS MAINTAINED THE STRONG CORE OF DEEP CONVECTION WITHIN THE EYEWALL AND THE MAIN FEEDER BAND ALONG THE WESTERN PERIPHERY. A RECENT 181001Z TRMM 85 GHZ MICROWAVE PASS SUPPORTS THE WELL-DEFINED STRUCTURE OF THE EYEWALL AND ALSO INDICATES SOME FRAGMENTATION OF THE FEEDER BAND ALONG THE EASTERN PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER. THE 15 NM EYE REMAINS CLOUD-FREE AND HAS MAINTAINED A VERY SYMMETRIC ORIENTATION AS THE SYSTEM TRACKS GENERALLY TO THE NORTHWEST UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE (STR) EXTENSION. THE CURRENT INTENSITY HAS BEEN MAINTAINED AT 125 KNOTS BASED ON STEADY DVORAK ESTIMATES FROM PGTW, AND LITTLE CHANGE IN THE ORGANIZATION OVER THE PAST SIX HOURS. UPPER LEVEL ANALYSIS INDICATES A POINT SOURCE ANTICYCLONE REMAINS OVER THE SYSTEM, PROVIDING AMPLE RADIAL OUTFLOW AND LOW (05-10 KNOTS) VERTICAL WIND SHEAR (VWS). 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING. B. THROUGH TAU 72, TY 26W IS EXPECTED TO SLOWLY TRACK NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR LOCATED WELL TO THE NORTH OF GUAM. FAVORABLE ENVIRONMENTAL CONDITIONS OF LOW VWS, WARM SEA SURFACE TEMPERATURES (SSTS), AND AMPLE OUTFLOW WILL ALLOW TY 26W TO INTENSIFY TO A MAXIMUM OF 135 KNOTS BY TAU 24. AFTER TAU 36, THE SYSTEM WILL START TO MOVE INTO LESS FAVORABLE SSTS, WHICH WILL IMPACT THE LOW LEVEL INFLOW, CAUSING A SLOW WEAKENING TREND TO BEGIN AND PERSIST THROUGH TAU 72. C. AFTER TAU 72, TY 26W WILL BEGIN TO ROUND THE WESTERN EXTENT OF THE STR, ALLOWING FOR A MORE NORTH-NORTHWESTWARD TRACK. A DECREASE IN SSTS AND AN INCREASE IN VWS WILL AMPLIFY THE WEAKENING TREND THROUGH TAU 120. NUMERIC MODEL GUIDANCE REMAINS WIDELY DIVERGENT IN THE EXTENDED TAUS, DUE TO THE VARIATIONS IN THE EXPECTED ORIENTATION OF THE STR AS A SERIES OF MID-LATITUDE TROUGHS PROGRESS TO THE NORTH OF THE STR. THE CURRENT FORECAST REMAINS CLOSE TO THE CONSENSUS OF AVAILABLE MODEL GUIDANCE AND THE ECMWF SOLUTION. DUE TO THE WEAKLY DEFINED STR EXTENSION, AND THE VARIATIONS IN THE EXTENDED TAUS, THE CONFIDENCE IN THE FORECAST REMAINS LOW.// NNNN