Tropical Storm TRAMI Advisory Fri Sep 28

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (TRAMI) WARNING NR 30//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 28W (TRAMI), LOCATED APPROXIMATELY 234 NM SOUTH OF
KADENA AB, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS TY 28W
CONTINUES TO HAVE A WIDE AND RAGGED EYE AND IS MAINTAINING DEEP
CONVECTION AROUND THE EYE. THE INITIAL POSITION IS BASED ON THE
LARGE EYE IN THE EIR LOOP WITH FAIR CONFIDENCE GIVEN THE WIDTH OF
THE EYE. THE INITIAL INTENSITY OF 90 KNOTS IS BASED ON KNES AND
PGTW DVORAK CURRENT INTENSITY ESTIMATES OF T5.0 (90 KTS) AND A
272246Z SATCON ESTIMATE OF 92 KTS, AND IS SLIGHTLY BELOW THE RJTD
ESTIMATE OF T5.5 (102 KTS). ENVIRONMENTAL ANALYSIS SHOWS THAT TY
28W IS EXPERIENCING FAVORABLE VERTICAL WIND SHEAR (5 TO 10 KNOTS,
WHILE POLEWARD OUTFLOW HAS SLACKENED DUE TO THE TROUGH TO THE
NORTHEAST MOVING AWAY. SEA SURFACE TEMPERATURES REMAIN FAVORABLE,
BETWEEN 28 AND 29 DEGREES CELSIUS. NOW THAT THE FORWARD MOTION OF
28W HAS INCREASED, IT IS LESS SUSCEPTIBLE TO THE LOWER OCEAN HEAT
CONTENT UNDERNEATH IT. TY 28W IS TRACKING NORTHWESTWARD ALONG THE
WESTERN PERIPHERY OF THE BURGEONING SUBTROPICAL RIDGE TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 28W WILL CONTINUE TO TRACK TO THE NORTHWEST ALONG THE STR
TO ITS EAST THROUGH TAU 12. BETWEEN TAU 12 AND TAU 24, TY 28W WILL
ROUND THE STR AXIS AND THEN START TO TRACK NORTHEASTWARD. AFTER TY
28W ROUNDS THE STR, A MIDLATITUDE TROUGH WILL BEGIN MOVING INTO THE
AREA, ENHANCING POLEWARD OUTFLOW ONCE AGAIN AND ALLOWING SLIGHT
INTENSIFICATION TO 105 KTS AT TAU 36. AFTER TAU 36, INCREASING VWS
AND LAND INTERACTION AS THE SYSTEM APPROACHES JAPAN WILL COMPETE
WITH THE ENHANCED POLEWARD OUTFLOW TO SLIGHTLY WEAKEN TY 28W. TY
28W WILL INTERACT WITH THE APPROACHING TROUGH AND BAROCLINIC ZONE
AND BEGIN EXTRATROPICAL TRANSITION (ETT). THE JTWC FORECAST TRACK
IS PLACED NEAR THE MULTI-MODEL CONSENSUS. DYNAMIC MODEL GUIDANCE IS
IN EXCELLENT AGREEMENT WITH 30 NM OF MODEL SPREAD AT TAU 36,
LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC FORECAST TRACK.
   C. AFTER TAU 72, TY 28W WILL HAVE TRANSITED OVER HONSHU AND
PASSED BACK OVER THE NORTHERN PACIFIC OCEAN. LAND INTERACTION,
STRONG VWS UNDER THE MIDLATITUDE WESTERLIES, AND COOLER SSTS BELOW
26 DEGREES CELSIUS WILL CONTRIBUTE TO TY 28W WEAKENING TO 55 KTS BY
TAU 72. TY 28W WILL HAVE ALSO COMPLETED ETT BY TAU 72 AND WILL
DISPLAY FRONTAL CHARACTERISTICS AND AN EXPANDED, ASYMMETRIC WIND
FIELD. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THAT TY 28W WILL
TRACK NORTHEASTWARD BUT THERE IS A WIDE RANGE IN TRACK SPEED. THE
JTWC FORECAST TRACK IS PLACED SLIGHTLY AHEAD OF THE MULTI-MODEL
CONSENSUS. OVERALL, THERE IS STILL LOW CONFIDENCE IN THIS PORTION
OF THE JTWC FORECAST TRACK.//
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