WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (WIPHA) WARNING NR 
07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 25W (WIPHA), LOCATED APPROXIMATELY 363 NM WEST-
NORTHWEST OF NAVSTA GUAM, HAS TRACKED NORTHWESTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL 
SATELLITE IMAGERY SHOWS DEEP CONVECTION CONTINUING TO CONSOLIDATE 
AROUND THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 112223Z SSMI-S 
MICROWAVE IMAGE DEPICTS A BROAD BAND OF DEEP CONVECTION WRAPPING 
INTO THE LLCC FROM THE SOUTHWEST AND DEEP CONVECTION IS BEGINNING TO 
WRAP AROUND THE NORTHERN SEMI-CIRCLE WITH SOME FRAGMENTATION. THE 
CURRENT POSITION IS BASED ON AN EXTRAPOLATION FROM THE 
AFOREMENTIONED MICROWAVE IMAGE AND HAS BEEN VERIFIED BY A MORE 
RECENT 120006Z AMSU-B PASS. THE CURRENT INTENSITY IS SLIGHTLY HIGHER 
THAN DVORAK ESTIMATES FROM ALL REPORTING AGENCIES BASED ON THE 
IMPROVING CORE STRUCTURE. UPPER-LEVEL ANALYSIS INDICATES FAVORABLE 
ENVIRONMENTAL CONDITIONS REMAIN IN PLACE, WITH LOW (5 TO 10 KTS) 
NORTHEASTERLY VERTICAL WIND SHEAR, AND STRONG RADIAL OUTFLOW 
OBSERVED IN ANIMATED WATER VAPOR IMAGERY. POLEWARD OUTFLOW IS ALSO 
BEING ENHANCED BY A TUTT CELL TO THE NORTHEAST. FURTHER IMPROVEMENT 
IS EXPECTED AS A WEAK TUTT CELL IS COMPLETING ITS TRANSITION OVER 
THE NORTHERN SEMICIRCLE OF THE SYSTEM. SOME UPPER-LEVEL CONVERGENCE 
CAN STILL BE SEEN OVER THE NORTHWESTERN QUADRANT BUT OVERALL OUTFLOW 
IS IMPROVING. THE CURRENT POSITION WIND RADII HAVE BEEN ADJUSTED 
BASED ON A TIMELY 120006Z ASCAT PASS. TS 25W IS TRACKING ALONG THE 
SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) 
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST TRACK PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 25W WILL TURN POLEWARD AS IT PROGRESSES ALONG THE 
SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE OVER THE NEXT 72 HOURS. 
FAVORABLE ENVIRONMENTAL CONDITIONS WILL DRIVE CONTINUED 
INTENSIFICATION TO A PEAK INTENSITY OF 110 KNOTS BY TAU 48. 
INTENSITY GUIDANCE SUGGESTS A HIGH LIKELIHOOD OF RAPID 
INTENSIFICATION WITHIN THE NEXT 24 HOURS AND FORECAST INTENSITY 
REFLECTS THIS WITH A 30-KNOT INCREASE FROM 60 KNOTS UP TO 90 KNOTS 
BY TAU 24. DURING TAUS 36-72, TS 25W SHOULD CONTINUE TO INTENSIFY AT 
A CLIMATOLOGICAL RATE BUT THE POSSIBILITY OF FURTHER RAPID 
INTENSIFICATION STILL EXISTS. DYNAMICAL TRACK GUIDANCE CONTINUES TO 
BE IN GOOD AGREEMENT, AND THE CURRENT FORECAST LIES CLOSE TO THE 
MULTI-MODEL CONSENSUS. BASED ON THE STRAIGHTFORWARD STEERING 
ENVIRONMENT AND AGREEMENT AMONG THE NUMERICAL MODELS, FORECAST TRACK 
CONFIDENCE DURING THIS PERIOD IS HIGH.
   C. IN THE EXTENDED PERIOD, TS 25W WILL ROUND THE STEERING RIDGE 
AXIS AND ACCELERATE TO THE NORTHEAST AHEAD OF A MIDLATITUDE TROUGH 
APPROACHING FROM THE NORTHWEST. INCREASING VERTICAL WIND SHEAR AND 
LOWER ALONG-TRACK SEA SURFACE TEMPERATURES WILL INDUCE STEADY 
WEAKENING. TS 25W SHOULD BEGIN TO INTERACT WITH THE BAROCLINIC 
TROUGH BEGINNING AROUND TAU 96, ACCELERATE RAPIDLY INTO THE MID- 
LATITUDE WESTERLIES THEREAFTER, AND COMPLETE A RAPID EXTRATROPICAL 
TRANSITION BY TAU 120. POST-RECURVATURE TRACK SPEEDS AMONG MODEL 
SOLUTIONS CONTINUE TO VARY SIGNIFICANTLY. THE JTWC FORECAST TRACK IS 
POSITIONED SLIGHTLY FASTER THAN THE MULTI-MODEL CONSENSUS IN THE 
EXTENDED PERIOD TO OFFSET THE SLOWER TRACKERS. HOWEVER, DUE TO 
UNCERTAINTY IN THE POST-RECURVATURE TRACK SPEEDS, CONFIDENCE IN THE 
EXTENDED TRACK FORECAST IS LOW.//
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