WDPN31 PGTW 192100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (DUJUAN) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.5N 137.7E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 420 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
24W (DUJUAN) WITH A HIGHLY COMPACT LOW-LEVEL CIRCULATION CENTER
(LLCC) THAT IS OBSCURED BY A SMALL CENTRAL DENSE OVERCAST (CDO).
THE COLDEST CLOUD TOPS ARE MEASURED TO BE COLDER THAN -80 C CLOSE
TO THE ASSESSED CENTER. ADDITIONALLY, A TIGHT CURVED BAND OF DEEP
CONVECTION HAS FORMED OVER THE PAST FEW HOURS ALONG THE NORTHERN
PORTION OF THE CIRCULATION. A LACK OF HIGH-RESOLUTION MICROWAVE
IMAGERY CAUSES THERE TO BE SOME UNCERTAINTY IN THE STRUCTURE OF THE
CORE AND POTENTIAL VORTEX TILT. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED PRIMARILY ON THE ANIMATED EIR IMAGERY. THE
INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AGENCY DVORAK FIXES AND CIMSS INTENSITY ESTIMATES
LISTED BELOW. ENVIRONMENTAL ANALYSIS INDICATES THAT 24W REMAINS
PLACED WITHIN A MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY
STRONG POLEWARD OUTFLOW ALOFT, LOW (10-15 KTS) SOUTHERLY VERTICAL
WIND SHEAR, DRY AIR ENTRAINMENT, AND WARM (28-29 C) SEA SURFACE
TEMPERATURES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) CENTERED TO THE EAST OF HONSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   CIMSS ADT: 49 KTS AT 191800Z
   CIMSS AIDT: 51 KTS AT 191800Z
   CIMSS D-MINT: 67 KTS AT 191639Z
   CIMSS D-PRINT: 66 KTS AT 191800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: SLIGHT DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 24W IS FORECAST TO IMMINENTLY BEGIN ON A
NORTHWARD TURN AS IT STARTS TO ROUND THE STEERING RIDGE AXIS. THE
NORTHWARD TRACK IS THEN EXPECTED TO PERSIST THROUGH TAU 18-24
BEFORE THE SYSTEM STARTS TO ACCELERATE NORTHEASTWARD ALONG THE
NORTHWESTERN PERIPHERY OF THE RIDGE. THE TIMING OF THE CPA TO
YOKOSUKA IS FORECAST TO OCCUR JUST AFTER TAU 36, AND REMAINS
LARGELY CONSISTENT WITH THE PREVIOUS FORECAST. AFTER TAU 36, TRACK
SPEEDS WILL BEGIN TO SIGNIFICANTLY INCREASE AS THE SYSTEM INTERACTS
WITH THE STRONG MID-LATITUDE WESTERLIES. EXTRATROPICAL TRANSITION
IS FORECAST TO BEGIN AT TAU 60 WITH COMPLETION AROUND TAU 72, ONCE
24W BECOMES FURTHER EMBEDDED UNDERNEATH THE JET AND THERMAL
ADVECTION INCREASES. IN TERMS OF INTENSITY, 24W IS FORECAST TO
MAINTAIN ITS CURRENT INTENSITY OF 65 KTS THROUGH TAU 36 DUE TO THE
STRONG POLEWARD OUTFLOW FIGHTING AGAINST DRY AIR AND INCREASING
SOUTHERLY VERTICAL WIND SHEAR. FROM TAU 48 TO TAU 60, A BRIEF
PERIOD OF INTENSIFICATION IS FORECAST TO OCCUR DUE TO 24W TAPPING
INTO AN EXTREME POLEWARD OUTFLOW CHANNEL, SUPPORTED BY A 150+ KNOT
JET MAXIMUM PLACED NORTHEAST OF HOKKAIDO. AFTER TAU 60, 24W IS
FORECAST TO BEGIN WEAKENING DUE TO COOLING SEA SURFACE
TEMPERATURES, VERY HIGH (OVER 50 KTS) WESTERLY VERTICAL WIND SHEAR,
AND SIGNIFICANT DRY AIR ENTRAINMENT.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGHOUT THE FORECAST PERIOD WITH A CROSS-TRACK SPREAD OF ABOUT
50 NM AT TAU 48 AND 105 NM AT TAU 72. ALONG-TRACK SPREAD DOES
INCREASE A BIT AFTER TAU 48 WITH GFS BEING THE NOTABLE SLOW OUTLIER
AMONG THE GUIDANCE. OVERALL, THE JTWC TRACK FORECAST IS PLACED
CLOSE TO THE MULTI-MODEL CONSENSUS THROUGH TAU 48 AND THEN SLIGHTLY
FASTER THROUGH TAU 72 WITH HIGH CONFIDENCE. INTENSITY GUIDANCE
GENERALLY AGREES ON A STEADY INTENSITY THROUGH TAU 36, FOLLOWED BY
BRIEF INTENSIFICATION FROM TAU 48-60 AND WEAKENING THEREAFTER.
HAFS-A HAS BECOME A SLIGHT OUTLIER, DEPICTING A PEAK INTENSITY OF
90 KTS AT TAU 48. THIS IS A POSSIBILITY IF 24W IS ABLE TO CONTAIN A
COMPACT CORE THAT FIGHTS OFF THE DRY AIR INTRUSION AND SOUTHERLY
SHEAR. AS IT STANDS, THE JTWC INTENSITY FORECAST IS PLACED NEAR THE
MODEL CONSENSUS WITH MEDIUM CONFIDENCE.

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