WDPN31 PGTW 011500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W
/WARNING NR 12//
RMKS/ 
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 011200Z4 DEC TO 051200Z8 DEC 2004.
   A. TYPHOON (TY) 30W (NANMADOL), LOCATED APPROXIMATELY 460 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT
19 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED
ON 011130Z6 ENHANCED INFRARED SATELLITE IMAGERY. THE WARNING
INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF
115 AND 127 KNOTS.
   B. TY 30W IS FORECAST TO CONTINUE TO TRACK RAPIDLY WEST-
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROP-
ICAL RIDGE ANCHORED TO THE NORTHEAST. TY 30W IS FORECAST TO MAKE
LANDFALL ALONG THE EAST COAST OF THE NORTHERN PHILIPPINES AT
APPROXIMATELY TAU 24, AND WILL TRACK INTO THE SOUTH CHINA SEA BY
TAU 36. AFTER TAU 36, TY 30W WILL BEGIN TO TRACK POLEWARD TOWARD
A DEVELOPING WEAKNESS IN THE STEERING RIDGE. THE AVAILABLE DYNAM-
IC AIDS CONSISTING OF NOGAPS, COAMPS, GFDN, AFWA MM5, NCEP GFS,
JGSM, JTYM, TCLAPS, UKMET, AND WBAR ARE IN FAIR AGREEMENT WITH
THIS SCENARIO, WITH ALL MODELS EXCEPT COAMPS FORECASTING RECURV-
ATURE BY TAU 48. THIS FORECAST IS BASED ON A CONSENSUS OF ALL
AVAILABLE DYNAMIC AIDS.
   C. THE INTENSITY OF TY 30W IS FORECAST TO DECREASE SLOWLY AFTER
TAU 24 AS THE SYSTEM INTERACTS WITH LAND AND ENTERS AN ENVIRONMENT
OF MODERATE VERTICAL WIND SHEAR. A BRIEF INCREASE IN INTENSITY IS
POSSIBLE AS THE SYSTEM CRESTS THE RIDGE AXIS AND INTERACTS WITH A
PASSING MID-LATITUDE TROUGH.
   D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR
A LARGE SIZED SYSTEM.
   E. IN THE EXTENDED TAUS, TY 30W IS FORECAST TO TRACK POLEWARD
THROUGH A WEAKENESS IN THE STEERING RIDGE CAUSED BY A MID-LATITUDE
TROUGH PROPGATING EASTWARD ACROSS CHINA. THE SYSTEM IS FORECAST TO
WEAKEN IN INTENSITY AS IT ENCOUNTERS INCREASED VERTICAL WIND SHEAR
IN THE SOUTH CHINA SEA. TY 30W WILL BEGIN TO UNDERGO EXTRATROPICAL
TRANSITION AFTER TAU 72 AS IT INTERACTS WITH THE MID-LATITUDE
TROUGH, AND IS FORECAST TO COMPLETE TRANSITION AND BECOME EMBEDDED
IN THE MID-LATITUDE WESTERLIES BY TAU 96.
3. FORECAST TEAM: BOWER/LAM/HEILER//