Tropical Depression SEPAT Advisory Bulletin (JTWC)
WTPN31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 02W (SEPAT) WARNING NR 016 //
RMKS/
1. TROPICAL DEPRESSION 02W (SEPAT) WARNING NR 016
02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
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WARNING POSITION:
260600Z --- NEAR 37.1N 142.9E
MOVEMENT PAST SIX HOURS - 045 DEGREES AT 18 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: 37.1N 142.9E
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FORECASTS:
12 HRS, VALID AT:
261800Z --- 40.6N 147.6E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
VECTOR TO 24 HR POSIT: 040 DEG/ 28 KTS
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24 HRS, VALID AT:
270600Z --- 44.7N 152.9E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
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REMARKS:
260900Z POSITION NEAR 38.0N 144.1E.
26JUN25. TROPICAL DEPRESSION 02W (SEPAT), LOCATED APPROXIMATELY
213 NM SOUTH-SOUTHEAST OF MISAWA, JAPAN, HAS TRACKED
NORTHEASTWARD AT 18 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL DEPRESSION
02W WITH AN INCREASINGLY ELONGATED AND ASYMMETRIC WIND FIELD. THE
SYSTEM HAS STARTED ITS TRANSITION INTO AN EXTRATROPICAL CYCLONE AS
IT APPROACHES THE BAROCLINIC ZONE AND THE UPPER-LEVEL JET. COOL SEA
SURFACE TEMPERATURES OF AROUND 23 C AND 20 KTS WESTERLY VERTICAL WIND
SHEAR INDICATE THAT 02W IS IN AN INCRASINGLY HOSTILE ENVIRONMENT FOR
TROPICAL DEVELOPMENT. 02W IS FORECAST TO CONTINUE ACCELERATING IN
THE NORTHEASTWARD DIRECTION AND COMPLETE EXTRATROPICAL TRANSITION
WITHIN THE NEXT 12 HOURS. AN INCOMING LONG WAVE TROUGH WILL PROPAGATE
EASTWARD AND BEGIN INTERACTING WITH THE SYSTEM, EXPEDITING THE
TRANSITION. BAROCLINIC FORCING WILL ALLOW THE VORTEX TO MARGINALLY
INTENSIFY OVER THE NEXT 24 HOURS AS THE SYSTEM BECOMES AN EXPANSIVE
COLD-CORE LOW. NUMERICAL MODEL GUIDANCE IS IN AGREEMENT REGARDING
BOTH THE TRACK AND INTENSITY OF 02W, LENDING HIGH CONFIDENCE TO THE
JTWC FORECAST. 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 260600Z IS
1006 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 260600Z IS 12 FEET.
REFER TO TROPICAL DEPRESSION 03W (THREE) FINAL WARNING
(WTPN32 PGTW).//
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Tropical Depression SEPAT Forecast Advisory (JTWC)
WDPN31 PGTW 260300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (SEPAT) WARNING
NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 35.7N 141.4E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 86 NM EAST-NORTHEAST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 15 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL DEPRESSION
(TD) 02W (SEPAT). THE SYSTEM IS COMPACT, WITH SPIRAL BANDS OF DEEP
CONVECTION WRAPPING INTO THE CENTER, HOWEVER CONVECTION IS SHALLOW
AND DOES NOT PERSIST FOR TOO LONG. ENVIRONMENTAL CONDITIONS ARE
BECOMING INCREASINGLY UNFAVORABLE FOR TROPICAL DEVELOPMENT. AS THE
SYSTEM MOVES POLEWARD AND EASTWARD, SEA SURFACE TEMPERATURES (SST)
ARE DECREASING, AND ARE CURRENTLY BELOW 23 C. VERTICAL WIND SHEAR
(VWS) IS ALSO INCREASING AND IS CURRENTLY ANALYZED AS MODERATE
(15-20 KTS). ADDITIONALLY, TD 02W IS CURRENTLY UNDERGOING AN
EXTRATROPICAL TRANSITION, WHILE POSITIONED AHEAD OF AN INCOMING DEEP-
LAYER TROUGH FROM THE WEST. THE INITIAL POSITION OF THE SYSTEM IS
DETERMINED WITH HIGH CONFIDENCE BASED ON THE CLEAR LLCC VISIBLE IN
SATELLITE IMAGERY. THE INITIAL INTENSITY IS ESTIMATED AT 25 KNOTS WITH
MEDIUM CONFIDENCE, SUPPORTED BY BOTH AGENCY DVORAK ESTIMATES AND
AUTOMATED ANALYSIS TOOLS.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS
CIMSS ADT: 32 KTS AT 252030Z
CIMSS AIDT: 39 KTS AT 252030Z
CIMSS D-MINT: 27 KTS AT 252043Z
CIMSS D-PRINT: 27 KTS AT 252250Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
VWS: 15-20 KTS
SST: 22-23 CELSIUS
OUTFLOW: WEAK RADIAL
OTHER FACTORS: SYSTEM IS UNDERGOING AN EXTRATROPICAL TRANSITION
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: TD SEPAT HAS CROSSED THE AXIS OF A STR TO THE
SOUTHEAST AND THE FORECAST TRACK INDICATES THAT THE SYSTEM WILL
FURTHER ACCELERATE NORTHEASTWARD ALONG THE NORTHWESTERN EDGE OF THE
RIDGE AND AWAY FROM MAINLAND JAPAN. AS THE SYSTEM CONTINUES TO
INTERACT WITH THE BAROCLINIC ZONE, IT IS FORECAST TO SLOWLY INTENSIFY,
DRIVEN BY THE BAROCLINIC FORCING. THE SYSTEM IS FORECAST TO COMPLETE
THE EXTRATROPICAL TRANSITION WITHIN THE NEXT 24 HOURS.
MODEL DISCUSSION: JTWC TRACK FORECAST CARRIES HIGH CONFIDENCE, AS
NUMERICAL MODEL GUIDANCE IS CLOSELY ALIGNED, WITH A CROSS-TRACK
SPREAD OF 60 NM BY TAU 24. HOWEVER, THERE IS SOME UNCERTAINTY
ASSOCIATED WITH THE ACCELERATION RATE OF THE SYSTEM, AS INDICATED
BY THE ALONG-TRACK GUIDANCE SPREAD OF 90 NM AT THE END OF THE
FORECAST PERIOD. THE INTENSITY FORECAST IS GIVEN MEDIUM CONFIDENCE.
WHILE ALL AVAILABLE MODELS SUGGEST STRENGTHENING THROUGH TAU 24, THE
DEGREE OF INTENSIFICATION DIFFERS AND THE SPREAD IS 15-20 KTS BETWEEN
THE MOST CONSERVATIVE HAFS, AND MOST AGGRESSIVE STATISTICAL-DYNAMICAL
MODEL. THE JTWC INTENSITY FORECAST CLOSELY FOLLOWS THE MULTI-MODEL
CONSENSUS.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: HIGH
INTENSITY 0 - 72 HR: MEDIUM//
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