WDPN32 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.4N 135.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 908 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 06W (KHANON) REMAINS BROAD, WITH MULTIPLE
LOW-LEVEL VORTICES EVIDENT IN THE ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI). A 280020Z ASCAT-B PASS SHOWED THE BROAD LOW LEVEL
CIRCULATION CENTER (LLCC) DRIFTED SOUTH THE PRECEDING SIX HOURS,
AND THEN SUBSEQUENTLY HAS PERFORMED A COUNTER-CLOCKWISE LOOP AND IS
NOW TRACKING TOWARDS THE NORTH. A 280432Z AMSR2 36GHZ MICROWAVE
IMAGE SHOWED WELL-DEFINED BANDING FEATURES ARCING ACROSS THE
SOUTHERN PERIPHERY OF THE CIRCULATION, BEGINNING TO WRAP UP THE
EASTERN SIDE, WITH FRAGMENTED SHALLOW BANDING ACROSS THE NORTHERN
HEMISPHERE. THE HIGH-RESOLUTION MICROWAVE ALSO SHOWED A BROAD LOW
EMISSIVITY REGION WITH POCKETS OF ENHANCED ROTATION, PROVIDING
INCREASED CONFIDENCE IN THE ASSESSMENT OF MULTIPLE VORTICES WITHIN
THE BROAD CENTER OF ROTATION. THE PRESENCE OF THE MULTIPLE VORTICES
AND THE USAGE OF THE CENTROID METHOD PRECLUDES PLACEMENT OF THE
INITIAL POSITION WITH ANYTHING MORE THAN LOW CONFIDENCE. THE
INITIAL INTENSITY IS INCREASED TO 35 KNOTS WITH MEDIUM CONFIDENCE,
HEDGED 5 KNOTS HIGHER THAN THE AGREED UPON T2.0 DVORAK CURRENT
INTENSITY ESTIMATES FROM ALL AGENCIES, IN LIGHT OF THE OBJECTIVE FIX
INTENSITIES (ADT, AIDT, DPRINT, DMINT AND SATCON) RANGING FROM
32-42 KNOTS. THE ENVIRONMENT REMAINS MARGINALLY FAVORABLE, WITH LOW
TO MODERATE (15-20 KNOTS) NORTHERLY SHEAR AND THE DISORGANIZED
NATURE OF THE VORTEX OFFSETTING THE STRONG EQUATORWARD OUTFLOW AND
WARM SSTS.

INITIAL WIND RADII BASIS: SCATTEROMETER AND AMSR2 WINDSPEED DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
NEAR-EQUATORIAL RIDGE (NER) CENTERED EAST OF THE MARIANAS. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 42 KTS AT 280422Z
   CIMSS ADT: 35 KTS AT 280530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 06W IS EXPECTED TO CONTINUE ON ITS SLOW AND
STEADY CONSOLIDATION TREND OVER THE NEXT 24 TO 36 HOURS AS IT
WOBBLES GENERALLY TOWARDS THE NORTH-NORTHWEST ALONG THE WEST SIDE
OF THE NER TO THE EAST. GIVEN THE UNCERTAINTIES IN THE INITIAL
POSITION, THE EXACT TRACK IS LIKELY TO SHIFT CONSIDERABLY LEFT AND
RIGHT OF THE MEAN THROUGH THE FIRST 24 TO 36 HOURS OF THE FORECAST.
UPPER-LEVEL CONDITIONS ARE MARGINALLY SUPPORTIVE AT BEST, WITH
NORTHERLY FLOW USHERING IN MODERATE SHEAR AND SOME MID-LEVEL DRY
AIR, INHIBITING AND SLOWING DEVELOPMENT OF A ROBUST CORE ON THE
NORTHERN SIDE. A WEAK TUTT-CELL IS CURRENTLY ANALYZED NEAR 24N
138E, MOVING TO THE WEST, AND HELPING TO CREATE A DEFORMATION ZONE
JUST NORTH OF TS 06W. THIS DEFORMATION ZONE IS EXPECTED TO
STRENGTHEN IN THE NEXT 24 HOURS OR SO, WHICH WILL LESSEN THE SHEAR
A BIT OVER TOP OF TS 06W. HIGH-RESOLUTION HAFS-A AND HWRF MODELS
SUGGEST THE MULTIPLE VORTICES WILL ULTIMATELY MERGE INTO ONE ROBUST
LLCC AROUND TAU 36 AND IN THE MEANTIME, THE SYSTEM WILL ONLY SLOWLY
INTENSIFY AT ROUGHLY THE CLIMATOLOGICAL RATE OF ONE T-NUMBER PER
DAY. BY TAU 36, THE TUTT-CELL WILL MOVE INTO A MORE FAVORABLE
POSITION, TO THE NORTHWEST OF TS 06W, ALLOWING FOR A DRAMATIC
INCREASE IN POLEWARD OUTFLOW, WHICH WILL SUPPORT A BURST OF RAPID
INTENSIFICATION BETWEEN TAU 48 AND TAU 72. AFTER TAU 72, THE
DEVELOPMENT OF AN ANTICYCLONE ALOFT SOUTH OF KYUSHU WILL INTRODUCE
EASTERLY SHEAR OVER TS 06W, BUT BY THIS POINT THE SYSTEM WILL
LIKELY BE STRONG ENOUGH TO COCOON ITSELF FROM THE EASTERLY SHEAR
AND IS FORECAST TO CONTINUE TO INTENSIFY A BIT PRIOR TO MAKING
LANDFALL IN THE VICINITY OF SHANGHAI BY TAU 120. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72, THOUGH CROSS-TRACK SPREAD HAS INCREASED TO 230NM AS
THE NAVGEM HAS STARTED TO PULL AWAY FROM THE PACK TO THE EAST AND
THE ECMWF AND ECENS ENSEMBLE HAVE BEGUN TO TRACK FURTHER SOUTH AND
WEST. THE REMAINDER OF THE GUIDANCE IN TIGHTLY PACKED ABOUT THE
CONSENSUS MEAN, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK
THROUGH TAU 72. AFTER TAU 72, THE GUIDANCE PACKAGE BEGINS TO
RESEMBLE A BIFURCATION, WITH THE ECMWF AND ECENS KEEPING THE STR IN
PLACE TO THE NORTH AND TRACKING THE SYSTEM INTO EASTERN CHINA
AROUND 27N. MEANWHILE THE NAVGEM, HWRF AND COAMPS-TC (NAVGEM) SHOW
THE RIDGING ERODING FROM THE WEST AHEAD OF A DEEP UPPER-LEVEL
TROUGH AND TURNING THE SYSTEM POLEWARD INTO THE EAST CHINA SEA
AROUND THE 125E LONGITUDE, GENERATING A 410NM SPREAD BY TAU 120. IN
THE LONGER TERM, BEYOND THE FORECAST, THE GFS, GEFS, EGRR AND UKMET
ENSEMBLE ALSO SHOW THE RIDGE BREAKING DOWN, ALLOWING THE SYSTEM TO
RECURVE, AND EARLY HINTS OF THIS SCENARIO ARE SHOWN IN THIS
FORECAST WITH THE TAU 120 POSITION PULLING SLIGHTLY MORE NORTH AND
EAST THAN THE PREVIOUS FORECAST. THE SUPER ENSEMBLE MEAN IS ALSO
BEGINNING TO PICK UP ON THIS SCENARIO, LENDING INCREASED CONFIDENCE
TO THE LONG-RANGE FORECAST. HOWEVER, DUE TO THE LARGE SPREAD IN THE
DETERMINISTIC TRACKERS AND THE INDIVIDUAL ENSEMBLE MEMBERS, THERE
IS MEDIUM CONFIDENCE IN THE LATER PORTION OF THE JTWC FORECAST
TRACK. INTENSITY GUIDANCE REMAINS IN GOOD AGREEMENT ON THE
INTENSIFICATION TREND, AND SIMILAR TO PREVIOUS FORECASTS, THE JTWC
FORECAST IS BELOW THE CONSENSUS THROUGH TAU 36, THEN DEVIATES FAR
ABOVE THE MEAN, BUT IS CONSISTENT WITH THE HWRF AND COAMPS-TC
ENSEMBLE PEAK, THROUGH TAU 96. CONFIDENCE IS MEDIUM DUE TO
UNCERTAINTY IN THE TIMING OF CONSOLIDATION AND THE JUMP OFF POINT
OF THE RI. 

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