Tropical Depression BAILU (13W)

WTPN32 PGTW 060300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL DEPRESSION 13W (BAILU) WARNING NR 017    
   01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   060000Z --- NEAR 40.2N 162.2E
     MOVEMENT PAST SIX HOURS - 070 DEGREES AT 15 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
   BECOMING EXTRATROPICAL
   REPEAT POSIT: 40.2N 162.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   061200Z --- 42.2N 166.3E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 070 DEG/ 20 KTS
    ---
   24 HRS, VALID AT:
   070000Z --- 43.4N 171.5E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
060300Z POSITION NEAR 40.7N 163.2E.
06AUG25. TROPICAL DEPRESSION 13W (BAILU), LOCATED APPROXIMATELY
959 NM EAST OF MISAWA, JAPAN, HAS TRACKED EAST-NORTHEASTWARD AT
15 KNOTS OVER THE PAST SIX HOURS. ANIMATED VISUAL AND SHORTWAVE
INFRARED IMAGERY SHOW THAT TD 13W IS WELL INTO THE EXTRA-TROPICAL
TRANSITION PHASE, BUT THE SYSTEM WILL WEAKEN TO BELOW 25 KNOTS
WELL BEFORE IT COMPLETES THE PROCESS. A MAJOR SHORTWAVE TROF
DIGGING OFF THE COAST OF ASIA IS AMPLIFYING THE LONG WAVE PATTERN
AND FORCING THE POLAR FRONT JET EVEN FURTHER POLEWARD, SLOWING THE
MERGE OF THE SYSTEM INTO THE WESTERLIES. NONETHELESS THE SATELLITE
ANIMATION SHOWS THE CORE BEGINNING TO FILL AND THE EARLY STAGES
OF COLD FRONTOGENESIS OVER THE SOUTHEAST QUADRANT. COLD AIR
STRATOCUMULUS FIELDS HAVE FILLED IN THE NORTHWESTERN QUADRANT.
BEFORE COMPLETING EXTRA-TROPICAL TRANSITION WITHIN THE NEXT 24 HOURS.
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 060000Z IS 982
MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 060000Z IS 12 FEET.
//
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WDPN32 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (BAILU) WARNING 
NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 39.7N 160.4E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 881 NM EAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL DEPRESSION 13W (BAILU) CONTINUES ITS LONG SLOW MERGE INTO
THE POLAR FRONT. ANIMATED ENHANCED INFRAED IMAGERY SHOWS COLD AIR
STRATOCUMULUS FIELDS AND DRY NORTHWESTERLIES PENETRATING INTO THE
SOUTHEASTERN QUADRANT AND COLD FRONTOGENESIS BECOMING ESTABLISHED
OVER THE SOUTHERN SEMICIRCLE, BUT THE EXPOSED LOW-LEVEL CIRCULATION
CENTER IS MAINTAINING A TIGHT WRAP. THE CORE OF THE SYSTEM IS
CROSSING THE 26C SST ISOTHERM AND HAS LOST SUPPORT FROM BOTH ABOVE
AND BELOW. THE JTWC FIX AND A 051529Z AMSR2 SERIES GIVES GOOD
CONFIDENCE TO PLACEMENT, AND RCTP, RJTD, AND PGTW DVORAKS ALL ALIGN ON
A 25KT INTENSITY. A 051056Z SCATTEROMETRY PASS ALSO CONFIRMED THE
INTENSITY. THE SYSTEM IS POLEWARD OF THE SUBTROPICAL RIDGE BUT THE
VIGOROUS WESTERLIES ASSOCIATED WITH THE POLAR FRONT JET ARE WELL
NORTH OF THE 45TH LATITUDE. THE TRAJECTORY OF THE STORM IN RELATION TO
THE JET IS BECOMING MORE PARALLEL, SO THE TRANSITION TO AN
EXTRA-TROPICAL CYCLONE WILL BE GRADUAL.

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

CURRENT STEERING MECHANISM: THE NORTHERN PERIMETER OF THE
SUBTROPICAL RIDGE AND THE EXTREME EQUATORWARD FLANK OF THE POLAR
FRONT JET. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   RCTP: T1.5 - 25 KTS
   CIMSS SATCON: 40 KTS AT 051700Z
   CIMSS ADT: 25 KTS AT 051740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 19-20 CELSIUS
   OUTFLOW: WEAK EASTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: IT WILL BE ANOTHER 18 TO 24 HOURS BEFORE TD
13W FULLY FINISHES EXTRA-TROPICAL TRANISTION. IN THE MEANTIME, IT
WILL TRACK NORTHEASTWARD AT A STEADY PACE AS MAKES ITS GRADUAL
TRANSITION INTO THE POLAR FRONT.  

MODEL DISCUSSION: TRACK GUIDANCE IS VERY TIGHT-THE MULTI MODEL
CONSENSUS WORKS FINE FOR THIS SYSTEM. BOTH STATISTICAL-DYNAMICAL
AND MESO-SCALE GUIDANCE SUCH AS HAFS-A SHOW A STEADY DECLINE IN
INTENSITY WITH NO FLARE UP INTO A SEVERE BAROCLINIC LOW AS THE
SYSTEM BECOMES EXTRA-TROPICAL. 

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