Advisories

WDPN33 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (KOGUMA) WARNING NR 029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.3N 147.3E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 571 NM SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AS INDICATED IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND 
MICROWAVE IMAGERY, THE EYEWALL REPLACEMENT CYCLE HAS COMPLETED WITH NO 
EVIDENCE YET OF A CONSOLIDATING, CONTRACTING EYE. EIR SATELLITE 
IMAGERY DEPICTED A ROUND, CLOUD-FREE EYE OF APPROXIMATELY 35-45NM 
DIAMETER AND COOLING CLOUD TOP TEMPERATURES. AN 112130Z SSMIS 91GHZ 
MICROWAVE IMAGE DEPICTS A COMPACT CONVECTIVE CORE OF 140-160NM, WITH 
SOME EROSION OF THE EYEWALL OVER THE SOUTHWEST QUADRANT. EXTENSIVE DRY 
AIR ENTRAINMENT AROUND THE PERIPHERY OF THE SYSTEM CONTINUES TO ERODE 
DEEP CONVECTION AROUND THE WESTERN AND SOUTHERN PERIPHERIES. UPPER-
LEVEL OUTFLOW REMAINS VIGOROUS WITH RADIAL OUTFLOW AND AN ENHANCED 
POLEWARD OUTFLOW CHANNEL REVEALED IN ANIMATED WATER VAPOR IMAGERY. 
THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION BASED ON THE CLOUD-
FREE EYE IN EIR SATELLITE IMAGERY AND THE WELL-DEFINED MICROWAVE EYE. 
THE INITIAL INTENSITY IS ASSESSED AT 100 KNOTS BASED ON A BLEND OF 
CIMSS OBJECTIVE ESTIMATES AND DVORAK CURRENT INTENSITY AND DATA-T 
ESTIMATES. THE WIND RADII WERE ADJUSTED RECENTLY BASED ON AN 112000Z 
RCM3 IMAGE WITH HIGH CONFIDENCE.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   CIMSS SATCON: 99 KTS AT 112130Z
   CIMSS ADT: 97 KTS AT 112340Z
   CIMSS AIDT: 97 KTS AT 112340Z
   CIMSS D-MINT: 94 KTS AT 112054Z
   CIMSS D-PRINT: 97 KTS AT 112300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: ENHANCED POLEWARD OUTFLOW CHANNEL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON (TY) 27W WILL RECURVE NORTH-NORTHEASTWARD 
TO NORTHEASTWARD OVER THE NEXT 12 TO 24 HOURS AS IT ROUNDS THE STR
AXIS. THERE IS A POSSIBILITY FOR SHORT-TERM REINTENSIFICATION
WITHIN THE NEXT 6-12 HOURS AS THE EYEWALL CONSOLIDATES AND
CONTRACTS AFTER THE EYEWALL REPLACEMENT CYCLE UNDER LOW VWS AND
WARM WATERS. AFTER TAU 12, THE SYSTEM IS EXPECTED TO WEAKEN QUICKLY AS 
VWS INCREASES TO 20-30 KNOTS. AFTER TAU 36, THE SYSTEM WILL ACCELERATE 
NORTHEASTWARD WITH MORE SIGNIFICANT WEAKENING AS IT ENCOUNTERS STRONG 
(40-50 KNOTS) VWS ASSOCIATED WITH THE MIDLATITUDE WESTERLIES AND 
COOLER SEA SURFACE TEMPERATURES (SST) LESS THAN 24C. EXTRA-TROPICAL 
TRANSITION (ETT) WILL COMMENCE NEAR TAU 48, WHEN TY 27W BEGINS TO 
INTERACT WITH THE UPPER-LEVEL JET STREAM AND MODERATE BAROCLINIC ZONE. 
THE SYSTEM WILL COMPLETE ETT BY TAU 72 AS IT TRACKS UNDER THE JET 
STREAM, GAINS WEAK TO MODERATE FRONTAL CHARACTERISTICS AND TRACKS OVER 
COLD SST VALUES (18-20C) WITH EXTENSIVE DRY AIR ENTRAINMENT.

MODEL DISCUSSION: OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC
TRACK AND INTENSITY FORECAST. PHYSICS-BASED AND AI-BASED GUIDANCE
REMAINS IN TIGHT AGREEMENT, WITH CONW, AICN AND GDMI IN CLOSE
AGREEMENT AT EVERY FORECAST TAU. RELIABLE INTENSITY GUIDANCE IS IN
GOOD AGREEMENT SUPPORTING THE STEADY WEAKENING FORECAST
PHILOSOPHY.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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