MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (TWENTYFOUR) WARNING NR 01// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 24W (TWENTYFOUR), LOCATED APPROXIMATELY 713 NM EAST OF ANDERSEN AFB, GUAM, HAS TRACKED NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A LARGE AREA OF ASYMMETRIC DEEP CONVECTION LOCATED OVER AN OBSCURED, ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC). A 021031Z MHS 89GHZ MICROWAVE IMAGE DEPICTS A PARTIALLY-EXPOSED, BROAD LLCC WITH THE BULK OF THE DEEP CONVECTION DISPLACED OVER THE EASTERN SEMICIRCLE. A 021112Z ASCAT-C IMAGE INDICATES THAT THE WINDFIELD HAS STRENGTHENED QUICKLY AND FORMED INTO A CLOSED CIRCULATION WITH A LARGE SWATH OF 30 KNOT WINDS OVER THE EASTERN SEMICIRCLE AND AN ISOLATED POCKET OF 35-40 KNOT WINDS OVER THE SOUTHEAST QUADRANT. DUE TO THE BROAD LLCC, THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION AND TRACK MOTION. THE CURRENT INTENSITY IS ASSESSED AT 30 KNOTS BASED ON AN OVERALL EVALUATION OF THE WINDFIELD. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH NEAR-RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR. ADDITIONALLY, SST VALUES OF 29-30C ARE CONDUCIVE FOR DEVELOPMENT. TD 24W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE FORECAST PHILOSOPHY. B. TD 24W IS FORECAST TO TRACK NORTHWESTWARD TO NORTH-NORTHWESTWARD THROUGH TAU 72 AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE STR AND APPROACHES THE STR AXIS. THE SYSTEM WILL INTENSIFY UNDER FAVORABLE CONDITIONS TO A PEAK OF 105 KNOTS WITH INCREASING POTENTIAL FOR RAPID INTENSIFICATION AFTER TAU 48 DUE TO ENHANCED POLEWARD OUTFLOW INTO THE MIDLATITUDE WESTERLIES. C. IN THE EXTENDED PERIOD, TD 24W WILL RECURVE NORTHEASTWARD AND IS FORECAST TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES. THE SYSTEM SHOULD COMPLETE ETT BY TAU 120 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. TD 24W WILL WEAKEN RAPIDLY DUE TO INCREASING VERTICAL WIND SHEAR AND COOLER SST BY TAU 120. DUE TO THE BROAD NATURE OF THE LLCC AND LARGE SPREAD IN SOLUTIONS IN THE EXTENDED PERIOD, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN