WDPN31 PGTW 310300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 25W (JEBI) WARNING NR 
16//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 25W (JEBI), LOCATED APPROXIMATELY 443 NM 
SOUTH-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED WESTWARD AT 12 KNOTS
OVER THE PAST SIX HOURS. STY 25W HAS RAPIDLY INTENSIFIED OVER THE 
PAST 24 HOURS (45 KNOTS) FROM 100 KNOTS TO THE CURRENT INTENSITY OF 
145 KNOTS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A 
COMPACT SYSTEM, APPROXIMATELY 140NM DIAMETER CENTRAL DENSE OVERCAST, 
WITH A 15NM ROUND EYE. A 302351Z MHS 89GHZ COLOR COMPOSITE IMAGE 
APPEARS TO INDICATE AN INCIPIENT EYEWALL REPLACEMENT CYCLE (ERC) 
WITH A SECONDARY EYEWALL FORMING AND A MOAT EVIDENT (AS PREDICTED IN 
THE UW-CIMSS P-ERC PRODUCT). THE INITIAL INTENSITY IS ASSESSED AT 
145 KNOTS BASED ON PGTW/RJTD DVORAK ESTIMATES OF T7.0 (140 KNOTS) 
AND A 302241Z SATCON ESTIMATE OF 150 KNOTS. UPPER-LEVEL ANALYSIS 
REVEALS A VERY FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR, 
RADIAL OUTFLOW ENHANCED BY A TUTT CELL TO THE EAST, WARM SST (29-
31C) AND HIGH OCEAN HEAT CONTENT VALUES. STY 25W IS TRACKING ALONG 
THE SOUTHERN PERIPHERY OF AN EAST-WEST ORIENTED SUBTROPICAL RIDGE 
(STR).
3. FORECAST REASONING. 
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE 
PREVIOUS WARNING. 
   B. STY 25W WILL CONTINUE TO TRACK WESTWARD TO WEST-NORTHWESTWARD 
THROUGH TAU 36 THEN WILL TURN NORTHWESTWARD TO NORTH-NORTHWESTWARD 
ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. NUMERICAL 
MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A SPREAD OF 
235NM AT TAU 72. BASED ON THE LOW UNCERTAINTY IN THE TRACK GUIDANCE, 
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST IS HIGH. 
ENVIRONMENTAL CONDITIONS ARE FORECAST TO REMAIN VERY FAVORABLE 
THROUGH TAU 48, THEREFORE, THE SYSTEM WILL MAINTAIN SUPER TYPHOON 
INTENSITY WITH A POTENTIAL PEAK OF 155 KNOTS IN THE NEXT 12 HOURS. 
DUE TO THE LIKELIHOOD OF ERC EVENTS OCCURRING, THERE IS SOME 
UNCERTAINTY IN THE EXACT JTWC INTENSITY FORECAST OVER THE NEXT FEW 
DAYS.  
   C. AFTER TAU 72, STY 25W WILL ACCELERATE NORTHWARD TO NORTH-
NORTHEASTWARD TOWARD CENTRAL HONSHU AS IT ROUNDS THE STR AXIS. STY 
JEBI IS EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY TAU 96 
AS IT BEGINS TO INTERACT WITH A DEEP MIDLATITUDE SHORTWAVE TROUGH 
DIGGING INTO THE KOREAN PENINSULA AND WESTERN JAPAN. STY 25W WILL 
RAPIDLY COMPLETE ETT AS IT BECOMES EMBEDDED WITHIN THE MIDLATITUDE 
SHORTWAVE TROUGH AND GAINS FRONTAL CHARACTERISTICS OVER THE SEA OF 
JAPAN. THE SYSTEM WILL RAPIDLY WEAKEN AFTER TAU 96 DUE TO INCREASING 
VERTICAL WIND SHEAR AND INCREASED FRICTIONAL EFFECTS. ADDITIONALLY, 
COLD SST VALUES SHOULD CONTRIBUTE TO FURTHER WEAKENING ONCE THE 
SYSTEM TRACKS BACK OVER THE SEA OF JAPAN. AFTER COMPLETING ETT, THE 
OCCLUDING EXTRA-TROPICAL LOW IS FORECAST TO MAINTAIN STORM-FORCE 
WINDS AS IT TRACKS POLEWARD. DUE TO THE INCREASING SPREAD IN THE 
NUMERICAL MODEL GUIDANCE ASSOCIATED WITH SIGNIFICANT DIFFERENCES IN 
THE TIMING OF THE RECURVE AND TRACK SPEEDS, THERE IS LOW CONFIDENCE 
IN THIS PORTION OF THE JTWC FORECAST TRACK.//
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