Typhoon Hagibis: extreme rapid intensification, forecast to reach cateogry 5 within 36h

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WESTERN NORTH PACIFIC

TY HAGIBIS(20W)
As of 00:00 UTC Oct 07, 2019:
Location: 15.1°N 149.5°E
Maximum Winds: 100 kt ( 185km/h)
Gusts: 125 kt ( 230km/h)
Minimum Central Pressure: 958 mb
CATEGORY 3 US
WDPN31 PGTW 070300
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.//
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