WDPN33 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (KRATHON) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.7N 123.1E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 483 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON 20W (KRATHON) IS SHOWCASING A MASSIVE EYE THAT IS
COMPLETELY ENCLOSED BY RAGGED, SPIRAL BANDING. THE MICROWAVE EYE
DIAMETER MEASURED ON A 290133Z MHS 89 GHZ IMAGE WAS
APPROXIMATELY 60 NM, VERSUS A 290916Z WSFM 89 GHZ MICROWAVE IMAGE
MEASUREMENT OF APPROXIMATELY 45 NM; THIS DEMONSTRATES THE EYE
STRUCTURE HAS CONTRACTED, CONSISTENT WITH THE RECENTLY EXPERIENCED 
PERIOD OF RAPID INTENSIFICATION (RI). A 291001Z RCM-3 NRCS IMAGE 
CONFIRMED THE PRESENCE OF A LARGE, RAGGED EYE, WHICH WAS POSITIONED 
SLIGHTLY OFF-TRACK COMPARED TO A DIRECT LINE BETWEEN POSITS DUE TO 
OBSERVED TROCHOIDAL MOTION SINCE THE LAST WARNING CYCLE. A HIGH-
RESOLUTION HIMAWARI-9 SATELLITE IMAGE REVEALED A RECENT PEAK EYE 
TEMPERATURE OF 23.7 C AT 291110Z. THE STRUCTURE REMAINS CIRCULAR WITH 
GOOD RADIAL OUTFLOW. THE INITIAL INTENSITY OF 95 KTS IS ASSESSED WITH
HIGH CONFIDENCE, HEDGED ABOVE THE CONSTRAINED, AGENCY SUBJECTIVE
DVORAK ESTIMATES, AND SUPPORTED BY MULTIPLE OBJECTIVE INTENSITY
ESTIMATES AND THE AFOREMENTIONED 291001Z RCM-3 PASS WHICH SHOWED A
WIDE BELT OF HIGH 80-KNOT WINDS TO HIGH 90-KNOT WINDS AND PEAKED AT
99 KTS. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED
ON AN EYE FIX IN THE ANIMATED ENHANCED INFRARED IMAGERY AND IS
CONSISTENT WITH THE RCM-3 IMAGERY.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WEAK STEERING BY A SUBTROPICAL RIDGE TO
THE DISTANT NORTHEAST.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 87 KTS AT 291059Z
   CIMSS ADT: 99 KTS AT 291130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-15 KTS
   SST: 28-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE BROAD HORIZONTAL EXTENT OF THE SYSTEM AND
THE WIDE DIAMETER OF THE EYE FEATURE INDICATE A PHYSICS CHALLENGE
FOR THE TYPHOON TO OVERCOME AS IT STRUGGLES TO REACH INTENSITIES
HIGHER THAN THOSE FORECASTED. THEREFORE, THE PERIOD OF RI WILL BE
LIMITED DESPITE A HIGHLY FAVORABLE ENVIRONMENT OF LOW VERTICAL WIND
SHEAR, WARM SEA SURFACE TEMPERATURES (SSTS), HIGH OCEAN HEAT
CONTENT VALUES, A VERTICALLY STACKED CORE, AND AN IMPROVING
POLEWARD OUTFLOW CHANNEL. THE NORTHWESTWARD TRACK WILL CONTINUE
UNTIL TAU 36 WHEN THE SYSTEM WILL PIVOT NORTHEASTWARD AND TRACK
ACROSS SOUTHERN TAIWAN SOON AFTER TAU 48. BEYOND TAU 72, A
DRASTICALLY WEAKENED SYSTEM WILL EMERGE AND CONTINUE TRACKING
NORTH-NORTHEASTWARD AT AN ACCELERATING PACE. SSTS WILL COOL BUT
STILL REMAIN FAVORABLE ENOUGH THAT THE SYSTEM COULD MAINTAIN A
WEAKENED INTENSITY FOR A WHILE AS IT APPROACHES HIGHER LATITUDES. A
TROUGH WILL MOVE INTO THE REGION FROM THE NORTHWEST BUT IS EXPECTED
TO FILL AND LIFT, AND THIS MAY HELP TO VENT KRATHON AND EVEN ALLOW
FOR FUTURE RESTRENGTHENING NEAR OR AFTER TAU 120. 

MODEL DISCUSSION: THE BULK OF THE TRACK GUIDANCE HAS ADVOCATED THE
CONTINUED FORECAST PHILOSOPHY TO MAKE A RIGHT-ANGLE TURN TO THE
NORTHEAST NEAR THE SOUTH OF TAIWAN, BUT INDIVIDUAL MODELS HAVE
STRUGGLED TO MAINTAIN CONSISTENCY BOTH IN PLACEMENT AND SPEED
RUN-TO-RUN. THE TRACK CONSENSUS SHOWS THE PIVOT POINT PULLED TOO
FAR WEST BY AN OUTLIER, WHICH HAS SUDDENLY PREDICTED A
STRAIGHT-RUNNER TRACK CONTINUING ON A WEST-NORTHWESTWARD TRACK,
WHEREAS THE BULK OF THE GUIDANCE OVERWHELMINGLY DISAGREES WITH THAT
SCENARIO. THE MORE RELIABLE MODELS HAVE SPED UP THE TRACK IN THE
LATER TAUS AND ALSO INDICATED A MORE NORTH-NORTHEASTERLY ADJUSTMENT
AFTER TAU 96. THE UNCERTAINTIES IN THE TRACK PLACEMENT AND SPEED
ARE REFLECTED IN THE POOR AGREEMENT OF THE INTENSITY GUIDANCE. MOST
GUIDANCE SHOWS A SLOWING PERIOD OF DEVELOPMENT WILL OCCUR FROM THIS
TAU FORWARD, PEAKING AT DIFFERENT TIMES IN THE REGION SOUTH OF
TAIWAN, BUT LARGELY LEVELING OFF IN DEVELOPMENT DUE TO THE ONSET OF
LAND INTERACTION. ALL MODELS AGREE WITH THE WEAKENING INTENSITIES
AROUND TAU 72, WITH SOME SUGGESTING A PLATEAU BETWEEN TAU 96 AND
TAU 120 OR EVEN A SLIGHT RE-INTENSIFICATION AT THE END OF THE
FORECAST PERIOD.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH
   INTENSITY 72-120 HR: MEDIUM//
NNNN