MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (TEN) WARNING NR 01// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 10W (TEN), LOCATED APPROXIMATELY 603 NM SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SOMEWHAT DISORGANIZED CIRCULATION, WITH DEEP FLARING CONVECTION DISPLACED SOUTHWEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). A 270030Z AMSU-B 89GHZ COMPOSITE MICROWAVE IMAGE REVEALS FORMATIVE BANDING WRAPPING INTO AN INCREASINGLY CONSOLIDATED LLCC, WITH THE AFOREMENTIONED DEEP CONVECTION DISPLACED WELL SOUTHWEST OF THE LLCC. THE INITIAL POSITION IS PLACED WITH MODERATE CONFIDENCE BASED ON AN ANALYSIS OF THE LOW LEVEL CONVECTIVE BANDS, SUPPORTED BY A 270030Z ASCAT-B PASS WHICH CONFIRMS THAT THE CENTER IS STILL FAIRLY BROAD BUT QUICKLY CONSOLIDATING INTO A TIGHTER CIRCULATION. THE INITIAL INTENSITY OF 25 KNOTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T1.5 (25 KNOTS) FROM BOTH PGTW AND RJTD, AS WELL AS THE PREVIOUSLY MENTIONED ASCAT PASS, WHICH CONFIRMS A LARGE SWATH OF 25 KNOTS WINDS TO THE SOUTH AND A SMALLER AREA OF 25 KNOT WINDS TO THE NORTH OF THE ASSESSED CENTER. THE ASCAT DATA ALSO SHOWS AN AREA OF 30-35 KNOT, WITH EVEN HIGHER WINDS ON THE EDGE OF THE SWATH, TO THE SOUTHWEST; HOWEVER, THE 30-35 KNOT WINDS ARE ISOLATED AND ARE UNDER A BURST OF DEEP CONVECTION DISPLACED FROM THE CENTER OF CIRCULATION AND ARE ASSESSED AS NOT REPRESENTATIVE OF THE OVERALL INTENSITY. ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR FURTHER DEVELOPMENT WITH LOW TO MODERATE (10-20 KNOTS) VERTICAL WIND SHEAR (VWS), STRONG DIVERGENT EQUATORWARD OUTFLOW AS WELL AS VERY WARM SST VALUES (31C) AND HIGH OCEAN HEAT CONTENT VALUES REFLECTING A DEEP, WARM POOL OF WATER. TD 10W IS CURRENTLY TRACKING SLOWLY WESTWARD IN A WEAK STEERING ENVIRONMENT BETWEEN A NEAR EQUATORIAL RIDGE (NER) THAT EXTENDS FROM THE PHILIPPINES EASTWARD ALONG 10 DEGREES NORTH LATITUDE, A STRONG SUBTROPICAL RIDGE (STR) TO THE NORTH AND A DEEP-LAYER SUBTROPICAL LOW CENTERED NEAR THE NORTHERN MARIANAS. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE FOR THIS SYSTEM AND SETS THE FORECAST PHILOSOPHY. B. THE WEAK STEERING PATTERN IS FORECAST TO REMAIN RELATIVELY STAGNANT THROUGH THE NEXT DAY, WHICH WILL RESULT IN A SLOW WESTWARD TRACK MOTION THROUGH TAU 24. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE THROUGH TAU 24 AS WELL, WITH DIVERGENT EQUATORWARD OUTFLOW, VERY WARM SSTS, HIGH OHC AND STEADILY DECREASING VWS, ALLOWING FOR STEADY INTENSIFICATION. BETWEEN TAU 24 AND TAU 36, THE UPPER LEVEL PATTERN BEGINS TO CHANGE, WITH THE NER MOVING NORTHWARD AND REORIENTING INTO A NORTH-SOUTH ORIENTATED RIDGE AXIS ALONG ROUGHLY THE 140 EAST LONGITUDE LINE, ALLOWING TD 10W TO SLOWLY TURN NORTHWARD. AT THE SAME TIME, A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL CURRENTLY NORTH OF GUAM WILL MOVE WEST INTO A POSITION NORTH-NORTHEAST OF THE SYSTEM. WHILE EQUATORWARD OUTFLOW WILL REMAIN ROBUST DURING THIS TIMEFRAME, THE TUTT WILL PROVIDE SOME CONVERGENT FLOW ON THE NORTH SIDE OF THE SYSTEM, LEADING TO A PERIOD OF SLOWER DEVELOPMENT. FROM TAU 36 TO TAU 72, THE NER-STR RIDGE COMPLEX TO THE EAST BECOMES ORIENTED NORTHWEST-SOUTHEAST, PUSHING TD 10W ONTO A FASTER TRACK TOWARDS THE NORTH-NORTHWEST. AT THIS TIME, THE TUTT WILL CONTINUE MOVING WEST AND AN UPPER LEVEL ANTICYCLONE IS FORECAST TO DEVELOP JUST EAST OF TD 10W ALLOWING FOR DEVELOPMENT OF A STRONG POLEWARD OUTFLOW CHANNEL, IN ADDITION TO THE ALREADY ESTABLISHED EQUATORWARD CHANNEL, LEADING TO A PERIOD OF RAPID INTENSIFICATION BETWEEN TAU 36 AND TAU 72. DYNAMIC MODEL GUIDANCE IS IN STRONG AGREEMENT IN THE OVERALL SCENARIO BUT DO HAVE SOME DISAGREEMENT IN THE EXACT TIMING OF THE TURN NORTH AND IN THE EXTENT OF THE WESTWARD MOTION IN THE NEAR-TERM, LEADING TO A 140NM SPREAD AT TAU 72. C. IN THE EXTENDED PERIOD, THE AFOREMENTIONED RIDGE COMPLEX TO THE EAST WILL REORIENT ONCE AGAIN TO A MORE NORTH-SOUTH AXIS, ALLOWING FOR A SLOW TURN ONTO A MORE NORTHWARD TRACK AFTER TAU 96. TD 10W IS FORECAST TO REACH PEAK INTENSITY OF 110 KNOTS AT TAU 96 UNDER VERY FAVORABLE CONDITIONS OF LOW VWS, ROBUST, DIVERGENT POLEWARD OUTFLOW AND VERY WARM SSTS. AS THE SYSTEM ENTERS THE EAST CHINA SEA, IT IS FORECAST TO WEAKEN SLIGHTLY, AS COOLER SSTS IN THE WAKE OF THE PASSAGE OF TY 09W THROUGH THE AREA AND INCREASING VWS, WILL OFFSET STRONG POLEWARD OUTFLOW INTO THE BASE OF AN APPROACHING MID-LATITUDE TROUGH. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 120. CROSS-TRACK SPREAD INCREASES TO A MODEST 178NM AT TAU 120 BUT ALONG- TRACK SPREAD INCREASES SIGNIFICANTLY FROM TAU 96 TO TAU 120 AS THE MODELS DIFFER IN THE AMOUNT OF INTERACTION WITH THE APPROACHING MID- LATITUDE TROUGH. THE JTWC FORECAST TRACK LIES WEST OF THE MULTI-MODEL CONSENSUS THROUGH TAU 72, FAVORING THE ECMWF SOLUTION, THEN LIES VERY CLOSE TO THE CONSENSUS, BUT FASTER, THROUGH TAU 120, WITH OVERALL MODERATE CONFIDENCE IN THE OFFICIAL TRACK.// NNNN NNNN