Tropical Depression YUN-YEUNG (12W)

WTPN31 PGTW 082100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 12W (YUN-YEUNG) WARNING NR 014//
RMKS/
1. TROPICAL DEPRESSION 12W (YUN-YEUNG) WARNING NR 014    
   01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   081800Z --- NEAR 34.5N 138.3E
     MOVEMENT PAST SIX HOURS - 020 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 34.5N 138.3E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   090600Z --- 36.2N 138.9E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 24 HR POSIT: 020 DEG/ 13 KTS
    ---
   24 HRS, VALID AT:
   091800Z --- 38.7N 140.0E
   MAX SUSTAINED WINDS - 015 KT, GUSTS 025 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
082100Z POSITION NEAR 34.9N 138.4E. 08SEP23. 
TROPICAL DEPRESSION 12W (YUN-YEUNG), LOCATED
APPROXIMATELY 84 NM SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED
NORTH-NORTHEASTWARD AT 10 KNOTS OVER THE PAST SIX HOURS.
ANIMATED PROXYVIS SATELLITE IMAGERY (PSI) SHOWS TROPICAL
DEPRESSION (TD) YUN-YEUNG (12W) RAPIDLY WEAKENING OVER THE LAST
SIX HOURS.  THE FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC)
HAS UNRAVELED INTO A WAVE LIKE FEATURE AND BEGUN DISSIPATION
OVER WATER. THE SYSTEM IS ANTICIPATED TO IMMINENTLY MAKE
LANDFALL ALONG THE NORTHERN SHORELINE OF THE SURUGA BAY AT
WEAK TROPICAL DEPRESSION INTENSITY.  THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON A 081800Z HM9 PROXYVIS
SATELLITE IMAGE AND TRIANGULATION FROM NEARBY SURFACE OBSERVATIONS, 
INCLUDING SHIZUHAMA AB AT JUST 15NM TO THE NORTH-NORTHWEST.  THE 
INITIAL INTENSITY IS PLACED WITH MEDIUM CONFIDENCE BASED ON 
PERSISTENCE AND RECENT SCATTEROMETRY DATA. THIS IS THE FINAL WARNING 
ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM 
WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MINIMUM CENTRAL 
PRESSURE AT 081800Z IS 1004 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 
081800Z IS 12 FEET.//
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WDPN31 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 12W (YUN-YEUNG) 
WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.6N 138.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 132 NM SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED PROXY VISIBLE SATELLITE IMAGERY (PSI) SHOWS A WEAK,
SHALLOW CIRCULATION NOW MOVING RAPIDLY TOWARDS THE SOUTHERN COAST
OF HONSHU. AFTER MEANDERING IN ROUGHLY THE SAME POSITION FOR ABOUT
18 HOURS, TROPICAL DEPRESSION (TD) 12W HAS FINALLY DETERMINED TO
MAKE ITS VISIT TO JAPAN AFTER ALL AND EJECTED NORTHWARD AT AN
ACCELERATING PACE. TRACK SPEEDS ARE NOW UP TO 11 KNOTS AND BY ALL
APPEARANCES LOOK TO PICK UP ANOTHER KNOT OR TWO OVER THE NEXT
COUPLE OF HOURS. A 090911Z GPM 37GHZ MICROWAVE IMAGE SHOWED SHALLOW
BANDING FEATURES DRAPED ACROSS THE NORTHERN HEMISPHERE, WRAPPING
INTO THE WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC), WITH AN
ELONGATED BAND OF SHALLOW CONVECTION EXTENDING NORTHEASTWARD TO THE
SOUTHERN TIP OF THE BOSO PENINSULA. A PARTIAL 091112Z ASCAT-C PASS
SHOWED A SHARP BOUNDARY EXTENDING FROM THE LLCC TO THE SAME AREA
SUGGESTIVE OF A DEVELOPING WARM FRONT. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC AND
EXTRAPOLATION OF THE MICROWAVE CENTER NOTED ABOVE. THE INITIAL
INTENSITY OF 30 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE, ON THE
HIGHER END OF THE AGENCY CURRENT INTENSITY ESTIMATES AND THE CIMSS
ADT ESTIMATE. THE ENVIRONMENT REMAINS HIGHLY UNFAVORABLE, WITH
EXTREMELY HIGH (35-40 KNOTS) SOUTHERLY SHEAR AND MID-LEVEL DRY AIR
SMOTHERING THE SYSTEM, OFFSETTING THE ROBUST POLEWARD OUTFLOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A SHALLOW,
NORTH-SOUTH ORIENTED SUBTROPICAL (STR) RIDGE CENTERED TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   CIMSS ADT: 27 KTS AT 081130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 35-40 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: MID-LEVEL DRY AIR. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: WITH THE RIDGE TO THE NORTH HAVING MOVED OFF
TO THE EAST AND INTEGRATED INTO A MUCH LARGER, NORTH-SOUTH ORIENTED
STR SITUATED ALONG THE 15OE LONGITUDE, TD 12W HAS BEEN KICKED OUT
ONTO A NORTHWARD TRAJECTORY OVER THE PAST SIX HOURS. THIS GENERAL
MOTION IS EXPECTED TO CONTINUE THROUGH THE SHORT DURATION OF THE
FORECAST PERIOD. TRACK SPEEDS ARE LIKELY TO PICK UP ANOTHER KNOT OR
TWO BEFORE THE SYSTEM MAKES LANDFALL, ALONG THE WESTERN SIDE OF
SURUGA BAY WITHIN THE NEXT FEW HOURS. ONCE IT MAKES LANDFALL, THE
CENTER WILL TRACK VERY NEAR MT. FUJI AND THEN CONTINUE FURTHER
INLAND TO CENTRAL HONSHU. DUE TO THE SHALLOW NATURE OF THE
CIRCULATION, MT. FUJI WILL HAVE AN OUTSIZE EFFECT ON THE SYSTEM,
WHICH WILL SLOW DOWN AND MOVE AROUND THE MOUNTAIN, WHILE AT THE
SAME TIME RAPIDLY DISINTEGRATING AS A DISCRETE CIRCULATION CENTER.
THE SYSTEM WILL CONTINUE TO WEAKEN AS IT APPROACHES THE COASTLINE,
THEN FULLY DISSIPATE WITHIN THE NEXT 24 HOURS OVER CENTRAL HONSHU. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE CONTINUES TO
STRUGGLE TO ACCURATELY PORTRAY THE FUTURE TRACK OF TD 12W, WITH
SOME MODELS (NAVGEM) TURNING THE SYSTEM SLOWLY TOWARDS THE
NORTHWEST, WHILE OTHER (ECENS MEAN) RACING THE SYSTEM TO A POSITION
EAST OF MISAWA BY TAU 24. THE JTWC FORECAST IS BASED PRIMARILY ON
AN EXTRAPOLATION OF THE RECENT TRACK MOTION AND EXPECTATIONS OF THE
LOCALIZED TERRAIN INFLUENCES. THE TRACK FORECAST REMAINS CONSISTENT
WITH THE PREVIOUS FORECAST WITH LOW CONFIDENCE. INTENSITY GUIDANCE
IS IN GOOD AGREEMENT ON THE RAPID WEAKENING TREND AND DISSIPATION
BY TAU 24, LENDING HIGH CONFIDENCE TO THE JTWC INTENSITY FORECAST. 

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