WDPN32 PGTW 260300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 19W
/WARNING NR 30//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 260000Z8 TO 310000Z4 AUG 2004.
   A. SUPER TYPHOON (STY) 19W (CHABA), LOCATED APPROXIMATELY 640
NM SOUTH-SOUTHEAST OF SASEBO, JAPAN, HAS TRACKED NORTH-
NORTHWESTWARD AT 08 KNOTS OVER THE PAST 06 HOURS. THE WARNING
POSITION IS BASED ON 252330Z5 MULTISPECTRAL SATELLITE
IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT
INTENSITY ESTIMATES OF 115 AND 140 KNOTS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY REVEALS CONVECTION HAS WEAKENED SUBSTANTIALLY
ALONG THE NORTHERN PERIPHERY DUE TO SOME DRY AIR ENTRAINMENT.
THE SOUTHERN PERIPHERY CONVECTION HAS MAINTAINED INTENSITY DUE
TO THE EQUATORIAL OUTFLOW CHANNEL.
   B. STY 19W IS FORECAST TO CONTINUE TRACKING AROUND THE
WESTERN PERIPHERY OF THE SUBTROPICAL STEERING RIDGE ANCHORED
TO THE EAST. DURING THE NEXT 48 HOURS, A MAJOR SHORTWAVE
TROUGH WILL ENTER THE NORTH PACIFIC EAST OF JAPAN AND WEAKEN
THE SUBTROPICAL RIDGE. ADDITIONALLY, A SECONDARY MAJOR SHORTWAVE
TROUGH WILL MOVE INTO NORTHEASTERN CHINA AND BUILD THE RIDGE AND
REORIENT THE RIDGE AXIS OVER THE SEA OF JAPAN. AS THE RIDGE
REORIENTS, STY 19W SHOULD BEGIN TO TURN WESTERLY AND TRACK
TOWARDS SOUTH KOREA. THE AVAILABLE DYNAMIC AIDS CONSISTING OF
COAMPS, UKMET EGRR, NCEP GFS, NOGAPS, GFDN, JGSM, WBAR, JTYM,
AND AFWA MM5 ARE IN FAIR AGREEMENT UP UNTIL TAU 48. THE
MODELS DIVERGE SUBSTANTIALLY AFTER THIS TIME. THIS FORECAST
IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS.
   C. STY 19W CONTINUES TO MAINTAIN AN EQUATORIAL OUTFLOW CHANNEL
AND CONVECTION HAS REMAINED WELL CONSOLIDATED AROUND THE EYE.
THE SYSTEM IS FORECAST TO CONTINUE WEAKENING THROUGH THE NEXT
72 HOURS AS STY 19W MOVES INTO A REGION OF INCREASED VERTICAL
WIND SHEAR. AS THE MIDLATITUDE MAJOR SHORTWAVE TROUGH PROPAGATING
EAST AWAY FROM JAPAN, ANY POLEWARD OUTFLOW SHOULD BECOME
MINIMAL.
   D. CURRENT WIND RADII ARE BASED IN PART ON A 252200Z1 QUIKSCAT
PASS. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR A LARGE
SIZED SYSTEM.
   E. AFTER TAU 72, THE CONFIDENCE IN THE FORECAST IS LOW. THIS IS
DUE TO THE LARGE DIVERGENCE IN THE NUMERICAL MODELS IN WHICH
UKMET EGRR, COAMPS AND NCEP GFS TAKE A MORE WESTWARD TRACK AND JTYM,
AFWA MM5 AND WBAR TAKE A MORE EASTWARD TRACK. THE CONSENSUS OF ALL
AIDS, INCLUDING GFDN AND NOGAPS RESOLVE A SOLUTION WHICH AGREE
WITH THE FORECAST TRACK. THE TIMING OF THE TURN AT TAU 72 WILL BE
HEAVILY DEPENDENT UPON HOW THE RIDGE AXIS BUILDS IN RESPONSE TO
THE SECONDARY MAJOR SHORTWAVE TROUGH.
3. FORECAST TEAM: MOHAMMED/LEFFLER/NOREN/LEWIN/SCHULTZ//