MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (HAGIBIS) WARNING NR 008// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 20W (HAGIBIS), LOCATED APPROXIMATELY 280 NM EAST- NORTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. TY 20W IS UNDERGOING EXTREME RAPID INTENSIFICATION (55 KNOTS IN 24 HOURS) FROM 45 KNOTS AT 06/00Z TO THE CURRENT INTENSITY ASSESSMENT OF 100 KNOTS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT EYEWALL WITH A SMALL 5 NM EYE. MSI INDICATES A SLIGHT WOBBLE IN THE TRACK MOTION. A 062336Z MHS 89GHZ IMAGE ALSO REVEALS A COMPACT CORE WITH EXTENSIVE SPIRAL BANDING OVER THE SOUTHERN SEMICIRCLE. UPPER-LEVEL ANALYSIS INDICATES RADIAL OUTFLOW (PLUS STRONG EQUATORWARD OUTFLOW AND ENHANCED POLEWARD OUTFLOW TO THE EAST) WITH LOW VERTICAL WIND SHEAR. SST VALUES OF 29-30C AND HIGH OCEAN HEAT CONTENT VALUES ALSO SUPPORT EXTREME RAPID INTENSIFICATION. THE CURRENT INTENSITY IS ASSESSED AT 100 KNOTS, HEDGED ABOVE DVORAK INTENSITY ESTIMATES OF T5.0 (90 KNOTS), BASED ON UNOFFICIAL DVORAK INTENSITY ESTIMATES FROM 0010- 0200Z INDICATING ESTIMATES INCREASING QUICKLY TO T6.5-7.0 (127-140 KNOTS). THE SYSTEM IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH. 3. FORECAST REASONING. A. TY 20W IS UNDERGOING EXTREME RAPID INTENSIFICATION, THEREFORE, THE INTENSITY FORECAST HAS BEEN ADJUSTED MUCH HIGHER THAN THE PREVIOUS FORECAST. THE TRACK FORECAST REMAINS HIGHLY CONSISTENT WITH THE PREVIOUS JTWC TRACK FORECAST. B. TY 20W IS FORECAST TO TRACK WEST-NORTHWESTWARD TO NORTHWESTWARD THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE STR POSITIONED TO THE NORTH. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN VERY FAVORABLE THROUGH THE FORECAST PERIOD WITH ROBUST OUTFLOW, WARM SST AND HIGH OCEAN HEAT CONTENT VALUES SUPPORTING RAPID INTENSIFICATION (RI) THROUGH TAU 24 WHEN THE SYSTEM WILL INITIALLY REACH SUPER TYPHOON STRENGTH. OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST THROUGH TAU 24 WITH A 60 NM SPREAD IN SOLUTIONS AT TAU 24. AFTER TAU 24, TY 20W WILL INTENSIFY SLIGHTLY UNDER FAVORABLE CONDITIONS. IMPROVED POLEWARD OUTFLOW WILL AID IN SUSTAINING SUPER TYPHOON STRENGTH UNTIL TAU 72, HOWEVER, THERE IS SIGNIFICANT UNCERTAINTY IN THE INTENSITY FORECAST DUE TO THE STRONG POSSIBILITY OF EYEWALL REPLACEMENT CYCLES WHICH CAN LEAD TO LARGE FLUCTUATIONS IN THE INTENSITY. NUMERICAL MODELS DIVERGE SO THERE IS INCREASING UNCERTAINTY IN THE LATER TAUS WITH A 231 NM SPREAD IN SOLUTIONS AT TAU 72. C. IN THE EXTENDED PERIOD, TY 20W WILL GENERALLY TRACK NORTHWESTWARD TO NORTH-NORTHWESTWARD TOWARD A BREAK IN THE STR ASSOCIATED WITH A DEEP, DYNAMIC SHORTWAVE TROUGH FORECAST TO DEEPEN OVER WESTERN JAPAN. THERE IS INCREASING UNCERTAINTY AS THE NUMERICAL MODEL GUIDANCE DIVERGES WITH A 480 NM SPREAD IN SOLUTIONS AT TAU 120. THE 06/12Z ECMWF ENSEMBLE STRIKE PROBABILITY PRODUCT ALSO INDICATES INCREASING UNCERTAINTY IN THE TIMING OF THE RECURVE SOUTH OF WESTERN JAPAN, THEREFORE, THERE IS LOW OVERALL CONFIDENCE IN THE JTWC TRACK FORECAST. NAVGEM (NVGI) AND GFS (AVNI) REMAIN OUTLIERS ON THE EASTERN EDGE OF THE AIDS ENVELOPE. TY 20W SHOULD BEGIN TO WEAKEN GRADUALLY DUE TO INCREASING VERTICAL WIND SHEAR AND SLIGHTLY COOLER SST VALUES.// NNNN NNNN