WDPN31 PGTW 080300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (MAN-YI) WARNING 
NR 26// 
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 080000Z8 TO 110000Z2 AUG 01.
   A.TYPHOON (TY) 12W (MAN-YI) LOCATED APPROXIMATELY 630 NM 
SOUTHEAST OF MISAWA, HAS TRACKED NORTH-NORTHEASTWARD AT 16 KNOTS
DURING THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON
072330Z5 VISIBLE AND INFRARED SATELLITE IMAGERY. THE WARNING
INTENSITY IS BASED ON CURRENT SATELLITE INTENSITY ESTIMATES OF 65,
77, AND 90 KNOTS. SATELLITE IMAGERY REVEALS COLD AIR WRAPPING INTO 
THE CIRCULATION CENTER FROM THE NORTH AND WEST. THE UPPER LEVEL 
CONVECTION IS TILTING EASTWARD AHEAD OF THE LOW LEVEL CIRCULATION 
CENTER, INDICATIVE OF THE EARLY STAGES OF EXTRATROPICAL TRANSITION. 
INFRARED IMAGERY SHOWS WEAKENING AND EROSION OF THE EYEWALL.  
   B. TY 12W CONTINUES TO TRACK NORTH OF THE UPPER LEVEL RIDGE 
AXIS. THE SYSTEM HAS BEGUN EXTRATROPICAL TRANSITION AND IS EXPECTED 
TO ACCELERATE NORTHEASTWARD AFTER THE 36- TO 48-HOUR FORECAST 
PERIOD. THE GEOPHYSICAL FLUID DYNAMICS-NAVY (GFDN), UKMET GLOBAL 
GRID-POINT (EGRR), THE JMA GLOBAL (JGSM) AND REGIONAL TYPHOON (JTYM) 
MODELS AND NOGAPS (NGPS) ARE IN GOOD AGREEMENT. NOGAPS INDICATES A 
MORE RAPID TRACK NORTHEASTWARD, POSSIBLY DUE TO EXCESSIVE 
INTERACTION WITH A BAROCLINIC SYSTEM TO THE NORTH. JTYM AND GFDN 
HAVE A SLOWER BIAS. THE NUMERICAL CONSENSUS CONSISTS OF FIVE 
OBJECTIVE AIDS: GFDN, EGRR, JGSM, JTYM, AND NOGAPS. THE OFFICIAL 
FORECAST IS A BLEND OF PERSISTENCE WITH THE DYNAMIC MODEL CONSENSUS.
   C. THE SYSTEM WILL CONTINUE TO WEAKEN AS IT TRACKS NORTH OF THE 
UPPER LEVEL RIDGE AXIS INTO A HIGHER VERTICAL WIND SHEAR 
ENVIRONMENT, AND OVER COOLER WATER. 
   D. WIND RADII ARE BASED ON A RECENT QUIKSCAT GALE WINDS ANALYSIS 
AND CLIMATOLOGY FOR AN AVERAGE-SIZED SYSTEM. WIND RADII ARE OMITTED 
FOR EXTRATROPICAL POSITIONS.
   E. THE JTWC WEBSITE HAS CHANGED TO: 
HTTPS://WWW.NPMOC.NAVY.MIL/JTWC.HTML. THIS CHANGE IS FOR SECURITY 
REASONS ONLY. THE CONTENT OF THE WEBSITE HAS NOT CHANGED.
FORECAST TEAM: COX/VILPORS/WAUGAMAN/SHERRY//



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