Possible Cat1 hit for Tokyo - shear dropping along forecasted track
Posted by JAC on 10/5/2009, 7:27 am











SUPER TYPHOON (STY) 20W (MELOR), LOCATED APPROXIMATELY 585 NM
SOUTHEAST OF OKINAWA, HAS TRACKED WEST-NORTHWESTWARD AT 16 KNOTS
OVER THE PAST SIX HOURS. DVORAK FIXES FROM PGTW AND RJTD INDICATE
THAT THE SYSTEM IS STILL OF SUPER TYPHOON CLASSIFICATION AT 140
KNOTS. THERE ARE NO SIGNIFICANT CHANGES FROM THE PREVIOUS FORECAST.
AFTER PASSING TO THE EAST OF OKINAWA THE SYSTEM IS EXPECTED TO TURN
TOWARDS THE NORTHEAST UNDER THE INFLUENCE OF 35 TO 50 KNOT
WESTERLIES ALOFT (CONFIRMED BY A 050000Z SKEW-T SOUNDING FROM
OKINAWA). THE SYSTEM WILL SLOWLY WEAKEN AS A TROPICAL SYSTEM DUE TO
INCREASED VERTICAL WIND SHEAR AND LOWER OCEAN HEAT CONTENT. SOUTH OF
TOKYO THE SYSTEM WILL BEGIN TO INTERACT WITH A BAROCLINIC BOUNDARY,
WEAKEN FURTHER, AND GAIN EXTRATROPICAL CHARACTERISTICS. THE SYSTEM
WILL BE FULLY EXTRATROPICAL, AND EMBEDDED WITHIN THE MID-LATITUDE
FLOW, BY TAU 96.


SUPER TYPHOON (STY) 20W (MELOR), LOCATED APPROXIMATELY 650 NM
SOUTHEAST OF OKINAWA, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL IMAGERY AND A
042158Z TRMM MICROWAVE IMAGE SHOW A VERY IMPRESSIVE SUPER TYPHOON
WITH A WELL-DEFINED, 26 NM EYE OUTLINED BY A SOLID RING OF INTENSE
CONVECTION FIRING WITHIN THE EYE WALL. STRONG CONVECTIVE BANDS ARE
WRAPPING TIGHTLY INTO THE LOW LEVEL CIRCULATION CENTER (LLCC),
ESPECIALLY FROM THE SOUTH. ON THE WESTERN SIDE OF THE SYSTEM, THERE
IS A REGION OF RELATIVELY DRIER AIR THAT IS BEGINNING TO WRAP INTO
THE WESTERN PERIPHERY OF THE SYSTEM. STY 20W CONTINUES TO HAVE
EXCELLENT RADIAL OUTFLOW. THE DVORAK SATELLITE CURRENT INTENSITY
ESTIMATES FROM PGTW AND RJTD HAVE BEEN STEADY FOR THE LAST 12 HOURS
AT 7.0 (140 KNOTS).
3. FORECAST REASONING
  A. THE FORECAST PHILOSOPHY HAS NOT SIGNIFICANTLY CHANGED SINCE
THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
  B. STY 20W WILL CONTINUE TRACKING WEST-NORTHWESTWARD ALONG THE
SOUTHERN PERIPHERY OF THE MID- TO UPPER LEVEL RIDGE TO THE
NORTHEAST. A STRONG BAROCLINIC BOUNDARY AND JET MAX CURRENTLY OVER
JAPAN IS ERODING THE RIDGE TO THE NORTH OF STY 20W AND WILL ALLOW
FOR RECURVATURE OF 20W. THE SYSTEM WILL REACH THE WESTERN EXTENT OF
ITS TRACK AROUND TAU 36. AFTER TAU 48, THE SYSTEM WILL ACCELERATE
RAPIDLY INTO THE MID-LATITUDE WESTERLIES AND GRADUALLY WEAKEN AS A
TROPICAL SYSTEM DUE TO DECREASED SEA SURFACE TEMPERATURES AND
INCREASED VERTICAL WIND SHEAR.
  C. AS STY 20W PASSES JUST SOUTH OF TOKYO AROUND TAU 72, THE
SYSTEM IS EXPECTED BEGIN EXTRA-TROPICAL TRANSITION (ET). THE
FORECAST CONTINUES TO LIE JUST OFFSHORE OF THE EASTERN COAST OF
JAPAN DUE TO STRONG UPPER LEVEL WESTERLIES, EXTENDING AS FAR SOUTH
AS SOUTH-CENTRAL JAPAN. ALL AVAILABLE GUIDANCE IS NOW TIGHTLY
CLUSTERED WITH JGSM AND WBAR NO LONGER OUTLIERS. THE LONE EXCEPTION
IS THE GFS MODEL THAT TAKES THE SYSTEM INTO CENTRAL JAPAN NEAR
KYOTO, JAPAN. THE JTWC FORECAST AND THE OTHER AVAILABLE CONSENSUS
MEMBERS BRING THE SYSTEM NEAR TOKYO AROUND TAU 72. BY TAU 96, THE
SYSTEM WILL HAVE COMPLETED EXTRA-TROPICAL TRANSITION.//



45
In this thread:
Melor the Monster - a solid Cat5, 914mb and dropping - JAC, 10/3/2009, 9:25 pm
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.