MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (TWO) WARNING NR 01// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 02W (TWO), LOCATED APPROXIMATELY 970 NM SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH IMPROVED DEEP CONVECTIVE BANDING OVER THE NORTHERN AND WESTERN SEMICIRCLES OF A PARTIALLY-EXPOSED, BROAD LOW-LEVEL CIRCULATION. A 190812Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE IMAGE (MI) DEPICTS SHALLOW BANDING OVER THE EASTERN SEMICIRCLE WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION CENTER POSITIONED ON THE EASTERN EDGE OF AN AREA OF PERSISTENT CORE CONVECTION AND FORMATIVE BANDING. BASED ON THE MI, THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T1.5 (25 KNOTS) FROM ALL AGENCIES. ENVIRONMENTAL CONDITIONS ARE VERY FAVORABLE WITH LOW TO MODERATE VERTICAL WIND SHEAR, GOOD EQUATORWARD OUTFLOW, STRONG POLEWARD OUTFLOW ENHANCED BY THE MIDLATITUDE WESTERLIES, WARM SST (29 TO 30C) AND HIGH OCEAN HEAT CONTENT VALUES. TD 02W IS CURRENTLY TRACKING WESTWARD ALONG THE SOUTHEASTERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AND NORTHWEST. 3. FORECAST REASONING. A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE FORECAST PHILOSOPHY. B. THROUGH TAU 72, TD 02W IS EXPECTED TO TRACK WESTWARD TO WEST- NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED STR ENTRENCHED TO THE NORTH. DUE TO THE FAVORABLE ENVIRONMENTAL CONDITIONS, THE SYSTEM IS FORECAST TO INTENSIFY STEADILY, NEAR CLIMATOLOGICAL RATE OF INTENSIFICATION, TO 70 KNOTS BY TAU 72. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A SPREAD OF 165NM AT TAU 72. C. IN THE EXTENDED PERIOD, UNCERTAINTY INCREASES SIGNIFICANTLY WITH A BIFURCATION IN THE MODEL GUIDANCE. GFS (AND THE GFS ENSEMBLE) AND NAVGEM INDICATE A RECURVE SCENARIO JUST WEST OF GUAM, WHICH APPEARS UNLIKELY (LOW PROBABILITY). BOTH THESE MODELS ERRONEOUSLY DRIVE THE SYSTEM DIRECTLY INTO AND THROUGH A STRONG STR POSITIONED OVER GUAM WITH NO MIDLATITUDE SHORTWAVE TROUGH PRESENT...IN FACT, GFS AND NAVGEM SHOW A BROAD STR TO THE EAST OF JAPAN. THE REMAINDER OF THE DYNAMIC MODEL GUIDANCE (ECMF, EEMN, HWRF, JGSM, EGRR) INDICATES A FLATTER TRACK MUCH FURTHER TO THE SOUTHWEST WITH A WEST- NORTHWESTWARD TO NORTHWESTWARD TRAJECTORY. THE JTWC OFFICIAL FORECAST FAVORS A NON-RECURVE SCENARIO CLOSER TO THE ECMWF SOLUTION DUE TO THE LACK OF A MIDLATITUDE RECURVE MECHANISM (DEEP SHORTWAVE TROUGH AND ASSOCIATED FRONTAL SYSTEM), AND PRESENCE OF A STRONG STR. TD 02W IS FORECAST, HOWEVER, TO INTENSIFY TO 90 KNOTS AS IT SKIRTS SOUTH OF GUAM, AND MAY STILL PRODUCE GALE-FORCE SUSTAINED WINDS AND ISOLATED GUSTS NEAR 50 KNOTS OVER GUAM. OVERALL, CONFIDENCE REMAINS LOW DUE TO THE BIFURCATION IN THE NUMERICAL GUIDANCE.// NNNN NNNN