WDPN31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MINDULLE) WARNING NR 030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.8N 135.9E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 603 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOW TYPHOON 20W
(MINDULLE) MAINTAINING EYEWALL INTEGRITY OVER THE PAST SIX HOURS,
LIKELY DUE TO A BOOST FROM DIURNAL CYCLING. BOTH SUBJECTIVE AND
OBJECTIVE DVORAK ASSESSMENTS WERE BEGINNING TO FALL, BUT AFTER
291500Z CLOUD TOPS RESUMED COOLING AND DATA T MEASUREMENTS ACTUALLY
ROSE AGAIN. THE EYE REMAINS ROUGHLY 40NM WIDE AND CORE TEMPS ARE
HOLDING STEADY, AND BOTH SATCON AND ADT VALUES ARE RISING AGAIN,
ALBEIT SLIGHTLY. A 291700Z AMSR2 SERIES DOES SHOW CLEAR
INDICATIONS OF DRIER AIR WRAPPING AROUND THE WESTERN SEMICIRCLE BUT
THUS FAR THE SYSTEM HAS BEEN ABLE TO ABSORB THE CHALLENGE. THE
CURRENT INTENSITY ASSESSMENT IS PREDICATED ON THE JTWC DVORAK
ANALYSIS AND SUPPORTED BY SATCON.

INITIAL WIND RADII BASIS: STALE SCATTEROMETRY COMBINED WITH THE
291701Z AMSR2 WINDSPEED PROFILE.

CURRENT STEERING MECHANISM: A HIGH AMPLITUDE RIDGE OVER THE
MARIANAS ANCHORED BY A 5910M 500MB HEIGHT CENTER JUST NORTHEAST OF
SAIPAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 110 KTS AT 291658Z
   CIMSS ADT: 99 KTS AT 291740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TYPHOON 20W HAS FINALLY CLOCKED OVER TO THE
EAST OF NORTH AND ENTERED ITS NORTHEASTWARD LEG. DUE TO THE
CLIMATOLOGICALLY ANOMALOUS HEIGHT CENTER OVER THE MARIANAS, THIS IS
NOT THE STEREOTYPICAL CASE OF THE STORM ROUNDING THE SOUTHWESTERN
FLANK OF THE SUBTROPICAL RIDGE AND ROARING INTO THE MID-LATITUDES. 
THE MARIANAS HIGH IS BLOCKING THE VORTEX FROM EASTWARD MOVEMENT AS
IT DRIFTS POLEWARD UNDER WEAK STEERING. THE RIDGE THAT EXTENDED
FROM AN ANTICYCLONE SOUTH OF SHANGHAI ALL THE WAY OVER THE RYUKUS
HAS PULLED BACK OVER THE PAST 48 HOURS AND IS ALLOWING THE STORM TO
MOVE POLEWARD MORE QUICKLY, BUT A WEDGE OF DRY SUBTROPICAL AIR
EXTENDING OVER THE RYUKUS IS KEEPING THE STORM SEPARATED FROM THE
MID-LATITUDE WESTERLIES. HENCE, ALTHOUGH THE STORM WILL TRACK 
POLEWARD AND EVENTUALLY UNDERGO TRANSITION INTO A 
MID-LATITUDE LOW, IT WILL DO SO AT A SLOWER RATE THAN TYPICAL FOR
THE SEASON. IN FACT, PHASE-BASED DIAGRAMS INDICATE THAT THE SYSTEM
WILL MAINTAIN ITS WARM CORE EVEN AFTER DEVELOPING THE FRONTAL
CHARACTERISTICS OF A WARM OCCLUSION (A SECLUSION AS OPPOSED TO AN
OCCLUSION). COUPLED MODELS INDICATE THAT 20W HAS SEEN ITS WARMEST
WATERS AND WILL TRACK THROUGH PROGRESSIVELY COOLER SEA WATERS.  THE
LEISURELY EXTRA-TROPICAL TRANSITION PERIOD WILL COMMENCE AFTER THE 
VORTEX CROSSES THE 30TH LATITUDE, ROUGHLY TAU 30, AND NOT BE FULLY
COMPLETE UNTIL THE STORM IS WELL NORTH OF THE KANTO PLAIN. 

MODEL DISCUSSION: TRACK GUIDANCE CONTINUES TO BE OUTSTANDING. THERE
ARE NOT EVEN ANY OUTLIERS IN THE MULTI-MODEL CONSENSUS TO COMPLAIN
ABOUT. INTENSITY GUIDANCE HAS ALSO CONGEALED WITH EACH SUCCESSIVE
MODEL RUN AND THE GAP BETWEEN STATISTICAL-DYNAMICAL AND
DETERMINISTIC GUIDANCE HAS CLOSED. THE JTWC FORECAST TRACK STAYS
STRAIGHT ON THE MULTI-MODEL CONSENSUS WHILE THE INTENSITY FORECAST
STAYS JUST ABOVE THE CONSENSUS AND CLOSER TO THE
STATISICAL-DYNAMICAL OUTPUT DURING THE FIRST 36 HOURS, THEN GOES
STRAIGHT ON CONSENSUS THROUGH THE DURATION OF THE FORECAST. 

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