Tropical Storm MEARI Advisory Per, 11.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE) WARNING
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 28.8N 135.8E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 437 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLOPPY AND
DISORGANIZED ROTATION, WITH MULTIPLE AREAS OF CIRCULATION, WITH
FLARING DEEP CONVECTION DISPLACED IN A BROAD ARC TO THE SOUTH OF AN
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION
IS ASSESSED WITH ONLY MEDIUM CONFIDENCE, WHILE BASED ON A
FULLY EXPOSED LLCC, IT IS BECOMING STEADILY ROPED OUT AND DIFFICULT
TO TRACK. HIGH RESOLUTION MODEL FIELDS HAVE BEEN HINTING AT
DEVELOPMENT OF A SECONDARY CIRCULATION CENTER TO THE
SOUTH-SOUTHEAST OF THE PRIMARY LLCC AND A 110624Z SSMIS 37GHZ
MICROWAVE IMAGE SEEMS TO BEAR THIS OUT, AS IT SHOWED A NASCENT
SECONDARY AREA OF CIRCULATION NEAR 28.1N 137.6E, APPROXIMATELY
110NM TO THE SOUTHEAST OF THE PRIMARY LLCC. ASIDE FROM THE
COMPLEXITY OF THE LOW LEVEL CIRCULATION (LLC), THE OVERALL
ENVIRONMENT IS MARGINALLY FAVORABLE, WITH WARM (29-30C) SSTS, AND
MODERATE TO STRONG POLEWARD OUTFLOW PROVIDED BY A WEAK UPPER-LEVEL
ANTICYCLONE JUST TO THE SOUTHEAST. NORTHERLY VERTICAL WIND SHEAR
(VWS) ACROSS THE AREA OF THE CIRCULATION IS MODERATE (15-20 KTS),
WHICH IS INHIBITING CONSOLIDATION OF THE CORE FOR THE MOMENT, AND
KEEPING CONVECTION PUSHED TO THE SOUTH. THE PRIMARY LLCC HAS
TRACKED WEST-NORTHWESTWARD OVER THE PREVIOUS DAY, BUT HAS SLOWED
AND TURNED TO THE WEST OVER THE PAST SIX HOURS AND LOOKS TO BE
TURNING SOUTHWARD AS OF THE 0700Z HOUR, WHILE THE LARGER ROTATION
IT IS PART OF CONTINUES MOVING SLOWLY WEST-NORTHWESTWARD ALONG THE
WESTERN SIDE OF THE SUBTROPICAL RIDGE (STR) TO THE EAST.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.
FORECAST DISCUSSION: AS DISCUSSED ABOVE, THE DEVELOPMENT OF A
SECONDARY CIRCULATION CENTER TO THE SOUTHEAST OF THE PRIMARY LLCC
IS ONGOING. HIGH RESOLUTION MODEL FIELDS SUGGEST THIS SECONDARY
VORTICITY CENTER WILL RAPIDLY MOVE NORTHWARD, WHILE THE PRIMARY
LLCC REMAINS QUASI-STATIONARY OR MOVES EASTWARD, WITH THE TWO AREAS
ULTIMATELY MERGING INTO ONE CONSOLIDATED CORE WITHIN THE NEXT 12 TO
24 HOURS. WHILE THIS MERGER AND CONSOLIDATION IS OCCURRING, THE
LARGER ROTATION IN WHICH THESE TWO CIRCULATIONS ARE EMBEDDED, WILL
MOVE SLOWLY NORTHWARD. AFTER THE CIRCULATION CONSOLIDATES, IT IS
FORECAST TO TURN NORTHEAST ALONG THE PERIPHERY OF THE DEEP STR
CENTERED TO THE EAST, MAKE LANDFALL ALONG THE IZU PENINSULA PRIOR
TO TAU 48, TRACK THROUGH THE TOKYO METRO AREA, AND THEN REEMERGE
OVER WATER AROUND TAU 60. THE SYSTEM WILL THEN CONTINUE
NORTHEASTWARD ALONG THE NORTHWEST PERIPHERY OF THE STEERING RIDGE,
WHILE UNDERGOING EXTRATROPICAL TRANSITION. IN THE NEAR TERM, THE
DISORGANIZED NATURE OF THE LOW LEVEL CORE MEANS THAT
INTENSIFICATION IS EXPECTED TO BE SLOW THROUGH TAU 12. THE
CONSOLIDATION OF THE CORE AROUND TAU 24 IS EXPECTED TO COINCIDE
WITH A REDUCTION IN THE VWS AS THE SYSTEM MOVES INTO A REGION UNDER
AN UPPER-LEVEL COL REGION, ALLOWING FOR SOME MARGINAL
INTENSIFICATION THROUGH TAU 36. AS THE SYSTEM TURNS TOWARDS THE
TOKYO REGION AFTER TAU 36, IT WILL BEGIN TO INTERACT WITH A 200MB
TROUGH MOVING OVER JAPAN, AND TAP INTO STRONG DIVERGENT EASTWARD
OUTFLOW ALOFT, WHICH WILL OFFSET INCREASING VWS AND ALLOW FOR A
BURST OF INTENSIFICATION TO NEAR TYPHOON STRENGTH, AS THE SYSTEM
PASSES TOKYO. ONCE BACK OVER WATER TD 09W WILL FEEL THE EFFECTS OF
STRONG WIND SHEAR AND DECREASING SSTS, AND RAPIDLY WEAKEN WHILE
SIMULTANEOUSLY BEGINNING EXTRATROPICAL TRANSITION (ETT). THE SYSTEM
IS FORECAST TO BECOME A FULLY EXTRATROPICAL LOW PRIOR TO
DISSIPATION, EAST OF THE KURILE ISLANDS.
MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
OVERALL GOOD AGREEMENT ON THE FORECAST TRACK, WITH A 105NM SPREAD
AT TAU 48 INCREASING TO WELL OVER 500NM BY THE END OF THE FORECAST
PERIOD. HOWEVER, THE GUIDANCE ENVELOPE, WHILE TIGHT, LIES TO THE
WEST OF THE JTWC FORECAST TRACK DUE TO THE FORECASTED INTERACTION
BETWEEN THE TWO POSSIBLE CIRCULATION CENTERS ASSOCIATED WITH TD 09W
AND THE DISPLACEMENT OF THE PRIMARY CIRCULATION THIS INTERACTION
WILL CAUSE. THUS THE TRACK LIES ON THE FAR EASTERN EDGE OF THE
GUIDANCE ENVELOPE THROUGH THE DURATION OF THE FORECAST, MOST
CLOSELY TRACKING THE HWRF SOLUTION. CONFIDENCE IN THE TRACK IS
MEDIUM DUE TO THE NEAR-TERM UNCERTAINTY. INTENSITY GUIDANCE IS
MIXED, WITH THE DECAY-SHIPS GUIDANCE INDICATING A PEAK OF 30 KNOTS,
WHILE THE HWRF SOLUTION FORECASTS A PEAK OF 75 KNOTS AT TAU 48 AND
THE CTR1 RAPID INTENSIFICATION AID SHOWING A PEAK OF 90 KNOTS. THE
JTWC FORECAST LIES BELOW MOST OF THE GUIDANCE THROUGH TAU 24 BUT
SLIGHTLY ABOVE THE CONSENSUS MEAN, BUT BELOW THE AGGRESSIVE HWRF,
THROUGH TAU 48. AS THE SYSTEM RAPIDLY DISSIPATES AFTER TAU 48, THE
JTWC FORECAST IS CONSISTENT WITH THE CONSENSUS MEAN. CONFIDENCE IS
LOW IN THE INTENSITY FORECAST, AS IT HINGES IN LARGE PART ON THE
TIMING BETWEEN THE CORE CONSOLIDATION AND 200MB TROUGH INTERACTION.
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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