MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (KHANUN) WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 20.4N 132.4E
INITIAL INTENSITY: 90 KTS
GEOGRAPHIC REFERENCE: 445 NM SOUTHEAST OF KADENA AB
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 31 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 06W HAS RAPIDLY INTENSIFIED 40 KNOTS OVER THE PAST 24
HOURS FROM 50 KNOTS AT 291200Z TO THE INITIAL INTENSITY OF 90
KNOTS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A ROUND
15NM EYE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.
A 301103Z GMI 89GHZ MICROWAVE IMAGE DEPICTS AN OBLONG EYEWALL WITH
A BREAK OVER THE NNW QUADRANT AND TIGHTLY-CURVED SPIRAL BANDING.
THE GMI 37GHZ MICROWAVE IMAGE SHOWS A MORE SYMMETRIC MICROWAVE EYE
FEATURE AND ALSO SUPPORTS THE INITIAL POSITION. ANIMATED WATER
VAPOR IMAGERY CONTINUES TO SHOW STRONG EQUATORWARD OUTFLOW AND
ROBUST POLEWARD OUTFLOW, WHICH HAS ALLOWED CORE CONVECTION TO
CONSOLIDATE RAPIDLY OVER THE PAST 12 HOURS. THE INITIAL INTENSITY
IS ASSESSED AT 90 KNOTS WITH MEDIUM CONFIDENCE AND IS BASED ON THE
PGTW, RCTP DVORAK ESTIMATES, THE CIMSS ADT ESTIMATE AS WELL AS A
PARTIAL 300905Z RCM-3 SAR IMAGE SHOWING 87 KNOT WINDS OVER THE
EASTERN QUADRANT. THE KNES DVORAK ESTIMATE OF T5.5 (102 KNOTS) IS
WITHIN THE RANGE OF UNCERTAINTY WITH THE 301330Z ADT ESTIMATES UP
TO 5.3 (97 KNOTS) AND THE RAW ADT ESTIMATES STEADY AT ABOUT T6.0
(115 KNOTS); THESE ESTIMATES SUGGEST THE INTENSITY COULD JUMP
HIGHER WITHIN THE NEXT SIX TO TWELVE HOURS.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
CENTERED SE OF TOKYO WITH RIDGE EXTENDING SOUTHWARD.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.0 - 90 KTS
RJTD: T4.0 - 65 KTS
RCTP: T5.0 - 90 KTS
KNES: T5.5 - 102 KTS
CIMSS SATCON: 87 KTS AT 301035Z
CIMSS ADT: 92 KTS AT 301200Z
D-PRINT: 96 KTS AT 301400Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 0-5 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: PEAK INTENSITY HAS BEEN INCREASED TO
115 KNOTS. FORECAST TRACK SPEEDS HAVE BEEN SLOWED SIGNIFICANTLY AFTER
TAU 72.
FORECAST DISCUSSION: THE JTWC TRACK FORECAST REMAINS HIGHLY
CONSISTENT WITH THE PREVIOUS JTWC TRACK FORECAST WITH NO SIGNIFICANT
CHANGE TO THE CPA AND CPA DISTANCE TO KADENA AB. OVERALL, OVER THE
PAST 3.5 DAYS, JTWC FORECASTS HAVE REMAINED WITHIN A 50NM ENVELOPE
JUST TO THE SOUTH OF OKINAWA. TY 06W WILL TURN GRADUALLY WEST-
NORTHWESTWARD AFTER TAU 24 AND CONTINUE TRACKING WEST-NORTHWESTWARD
THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE STR POSITIONED TO
THE NORTH AND NORTHEAST. BASED ON THE HIGHLY FAVORABLE ENVIRONMENTAL
CONDITIONS AND AFOREMENTIONED RAW ADT ESTIMATES, THE PEAK INTENSITY
HAS BEEN INCREASED TO 115 KNOTS AT TAU 36. AFTER TAU 72, THE SYSTEM
IS NOW FORECAST TO SLOW SIGNIFICANTLY AS IT APPROACHES THE EASTERN
COAST OF CHINA WITH LANDFALL EXPECTED NEAR TAU 96. DUE TO THE LARGE
SIZE OF THE SYSTEM AND ITS EXPANSIVE GALE-FORCE WINDS, NEAR GALE-
FORCE WINDS MAY PERSIST AFTER THE SYSTEM TRACKS WEST OF OKINAWA.
MODEL DISCUSSION: THE 300600Z ECMWF (EPS) AND GFS (GEFS) ENSEMBLES
INDICATE A BIFURCATION IN PROBABILISTIC GUIDANCE WITH TWO DISTINCT
CLUSTERS. THE FIRST CLUSTER SUPPORTS A WNW TRACK INTO EAST CENTRAL
CHINA AND DISSIPATION SCENARIO. THE SECOND CLUSTER REVEALS A SLOW
POLEWARD TRACK OVER THE EAST CHINA SEA TOWARD THE KOREAN PENINSULA
(NOTE: THIS COVERS THE NEXT 5 DAYS ONLY). DETERMINISTIC GUIDANCE
REMAINS IN TIGHT AGREEMENT THROUGH TAU 48 WITH A CROSS-TRACK
SPREAD NEAR OKINAWA RANGING FROM 50NM AT TAU 36 TO 80 NM AT TAU 48.
RAPID INTENSIFICATION (RI) WILL LIKELY CONTINUE FOR THE NEXT 24 TO 36
HOURS WITH RI GUIDANCE TRIGGERED AND THE 300600Z COAMPS-TC ENSEMBLE
INDICATING A 20 TO 30 PERCENT PROBABILITY OF RI. AFTER TAU 48,
DETERMINISTIC GUIDANCE DIVERGES WITH A VERY NOTICEABLE DECREASE IN
TRACK SPEEDS OVER EASTERN CHINA OR OFF THE COAST. CONSEQUENTLY,
CONFIDENCE IS LOW IN THE EXTENDED PERIOD. THE GFS DETERMINISTIC
SOLUTION IS PARTICULARLY PROBLEMATIC WITH GFS QUICKLY BREAKING DOWN
THE STR AND SHOWING A STALL NEAR 125E; THIS SCENARIO WILL BE WATCHED
CAREFULLY SINCE IT COULD IMPACT OKINAWA. THE JTWC FORECAST PHILOSOPHY
CONTINUES TO FAVOR THE WNW MODEL GROUPING AND THE ECMWF ENSEMBLE
(EPS) SINCE GFS CONTINUES TO TRACK THE SYSTEM DIRECTLY INTO THE STR
TO THE NORTH WITH NO DYNAMIC SHORTWAVE TROUGH EVIDENT IN THE ZONAL
MIDLATITUDE FLOW.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//
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