Super Typhoon Hagibis: eyewall replacement cycle not completed

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WESTERN NORTH PACIFIC

STY HAGIBIS(20W)
As of 06:00 UTC Oct 08, 2019:
Location: 17.7°N 142.6°E
Maximum Winds: 135 kt ( 250km/h)
Gusts: 165 kt ( 305km/h)
Minimum Central Pressure: 920 mb
CATEGORY 4 US
WDPN31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 20W (HAGIBIS) WARNING NR
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON 20W (HAGIBIS), LOCATED APPROXIMATELY 274 NM NORTH-
NORTHWEST OF ANDERSEN AFB, HAS TRACKED NORTHWESTWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS SPIRAL CONVECTIVE BANDS WRAPPING INTO A TIGHT, 5 NM
DIAMETER PINHOLE EYE AND A DEFINED MOAT BETWEEN THE PRIMARY EYEWALL
AND THE SECONDARY EYEWALL. THE INITIAL INTENSITY ESTIMATE REMAINS
135 KTS BASED ON THE DVORAK CURRENT INTENSITY (CI) ESTIMATES OF T7.0
(140 KTS) FROM PGTW AND RJTD AND T6.5 (127 KTS) FROM KNES. THE
AUTOMATED DVORAK TECHNIQUE ESTIMATE AT 080540Z IS LOWER, AT T6.2
(120 KTS). WIND RADII WERE ADJUSTED USING A 080023Z METOP-C ASCAT
PASS. THE SYSTEM HAS BEEN UNDERGOING AN EYEWALL REPLACEMENT CYCLE
(ERC), WITH AN ERODING PRIMARY EYEWALL AND SURROUNDING SECONDARY
EYEWALL APPARENT IN ENHANCED INFRARED SATELLITE IMAGERY AND A
080325Z AMSR-2 89GHZ MICROWAVE IMAGE. UPPER-LEVEL ANALYSIS INDICATES
SUSTAINED STRONG RADIAL OUTFLOW, ENHANCED TOWARDS THE EAST AND
SOUTH. TO THE NORTH OF THE SYSTEM, THERE IS AN AREA OF DRY AIR WITH
HIGH VERTICAL WIND SHEAR (VWS), INHIBITING DEVELOPMENT OF A STRONG
POLEWARD OUTFLOW CHANNEL. STY 20W REMAINS IN A FAVORABLE ENVIRONMENT
CHARACTERIZED BY LOW (10-15 KTS) VWS AND WARM (29-31 CELSIUS) SEA
SURFACE TEMPERATURES (SST). STY 20W HAS TURNED TOWARDS THE NORTHWEST,
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR)
TO THE NORTHEAST.
3. FORECAST REASONING.     
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE LAST PROGNOSTIC REASONING MESSAGE.
   B. AFTER TAU 24, A PASSING MIDLATITUDE TROUGH TO THE NORTH WILL
CAUSE THE STR TO RE-ORIENT, ALLOWING STY 20W TO SHIFT TO A MORE
NORTH-NORTHWESTWARD TRACK AS IT ROUNDS THE RIDGE AXIS. THE
ENVIRONMENT IS EXPECTED TO REMAIN FAVORABLE THROUGH TAU 72 WITH LOW
VWS, HIGH SST, AND GOOD UPPER-LEVEL OUTFLOW. THE OFFICIAL INTENSITY
FORECAST REFLECTS THE POSSIBILITY OF SLIGHT RE-INTENSIFICATION AS
THE ERC COMPLETES AND THE NEW, BROADER PRIMARY EYEWALL CONTRACTS,
AND IS STILL ABOVE THE MULTI-MODEL INTENSITY CONSENSUS. AFTERWARDS,
GRADUAL WEAKENING IS EXPECTED AS THE OUTFLOW BEGINS TO BE DISRUPTED
TO THE NORTHWEST DUE TO INTERACTION WITH AN APPROACHING TROUGH. GFS
AND THE GFS ENSEMBLE ARE THE EASTERNMOST OUTLIERS, DEPICTING A
SOONER RECURVE AND WEAKER STR, THE UKMET SOLUTION IS THE WESTERNMOST
OUTLIER, AND THE ECMWF SOLUTION IS IN LINE WITH BUT SLIGHTLY AHEAD
OF THE MULTI-MODEL CONSENSUS. THIS PORTION OF THE JTWC TRACK
FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH GOOD
CONFIDENCE.
   C. IN THE EXTENDED PERIOD, A SHORTWAVE TROUGH OVER JAPAN WILL
MOVE THROUGH THE AREA, AGAIN ERODING THE STR AND ALLOWING STY 20W TO
RECURVE AFTER TAU 72. THE SYSTEM WILL SLOWLY WEAKEN IN RESPONSE TO
INCREASED VWS ASSOCIATED WITH THE APPROACHING TROUGH, OFFSETTING THE
OTHERWISE FAVORABLE ENVIRONMENT. AT TAU 120, THE SYSTEM IS FORECAST
TO BEGIN INTERACTING WITH THE BAROCLINIC ZONE; OUTFLOW WILL
DIMINISH, VWS WILL INCREASE FURTHER, AND THE SYSTEM WILL ACCELERATE
TOWARDS THE NORTHEAST AND BEGIN EXTRATROPICAL TRANSITION. CROSS-
TRACK AGREEMENT IS GOOD, WITH APPROXIMATELY 175 NM OF SPREAD.
HOWEVER, THE TIMING OF THE RECURVE AND EXTRATROPICAL TRANSITION VARY
BETWEEN MODELS. ALONG TRACK SPREAD IS 730 NM AT TAU 120, WITH UKMET
AND GALWEM BEING THE SLOWEST MODELS, WEST OF CONSENSUS AND BRINGING
THE SYSTEM OVER HONSHU, ECMWF JUST SKIRTING THE HONSHU COASTLINE AND
IN LINE WITH AND SLIGHTLY AHEAD OF CONSENSUS, AND GFS AND JGSM
SIGNIFICANTLY FASTER THAN AND EAST OF THE MULTI-MODEL CONSENSUS. DUE
TO THE VARIATION IN THE TIMING OF THE RECURVATURE AND ALONG-TRACK
SPEEDS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST
TRACK.//
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