WPAC: YUN-YEUNG - Post-Tropical

[Hayabusa]

99W INVEST 230904 0000 20.0N 130.0E WPAC 15 0

[Hayabusa]

TD a
Issued at 2023/09/04 04:15 UTC
Analysis at 09/04 03 UTC
Grade TD
Scale -
Intensity -
Center position N20°05′ (20.1°)
E130°05′ (130.1°)
Direction and speed of movement NNE Slow
Central pressure 1004 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 09/05 03 UTC
Grade TS
Intensity -
Center position of probability circle N23°35′ (23.6°)
E131°35′ (131.6°)
Direction and speed of movement NNE 15 km/h (9 kt)
Central pressure 1000 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 130 km (70 NM)
Forecast for 09/06 00 UTC
Grade TS
Intensity -
Center position of probability circle N28°25′ (28.4°)
E134°30′ (134.5°)
Direction and speed of movement NNE 30 km/h (16 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 200 km (110 NM)
Forecast for 09/07 00 UTC
Grade STS
Intensity -
Center position of probability circle N34°00′ (34.0°)
E139°50′ (139.8°)
Direction and speed of movement NE 35 km/h (18 kt)
Central pressure 990 hPa
Maximum sustained wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 260 km (140 NM)
Forecast for 09/08 00 UTC
Grade TS
Intensity -
Center position of probability circle N37°35′ (37.6°)
E143°00′ (143.0°)
Direction and speed of movement NNE 20 km/h (11 kt)
Central pressure 992 hPa
Maximum sustained wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 330 km (180 NM)
Forecast for 09/09 00 UTC
Grade TS
Intensity -
Center position of probability circle N42°30′ (42.5°)
E147°10′ (147.2°)
Direction and speed of movement NNE 30 km/h (15 kt)
Central pressure 994 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 440 km (240 NM)

[Hayabusa]

ABPW10 PGTW 040600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS/040600Z-050600ZSEP2023//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/040153ZSEP2023//
REF/B/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/031352ZSEP2023//
NARR/REF A IS A TROPICAL CYCLONE WARNING. REF B IS A TROPICAL CYCLONE
FINAL WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 04SEP23 0000Z, TYPHOON 10W (HAIKUI) WAS LOCATED NEAR
23.2N 119.8E, APPROXIMATELY 147 NM SOUTHWEST OF TAIPEI, TAIWAN, AND
HAD TRACKED NORTH-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS.
MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 75 KNOTS GUSTING TO
90 KNOTS. SEE REF A (WTPN33 PGTW 040300) FOR FURTHER DETAILS.
(2) AT 03SEP23 1200Z, TROPICAL DEPRESSION 09W (SAOLA) WAS
LOCATED NEAR 20.7N 109.0E, APPROXIMATELY 175 NM EAST OF HANOI,
VIETNAM, AND HAD TRACKED SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX
HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 25 KNOTS
GUSTING TO 35 KNOTS. SEE REF B (WTPN32 PGTW 031500) FOR THE FINAL
WARNING ON THIS SYSTEM.
(3) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR 20.0N
129.1E, APPROXIMATELY 390 NM SOUTH-SOUTHEAST OF KADENA, AB. ANIMATED
MSI AND A 040124Z BULLSEYE ASCAT METOP-C PASS REVEAL A PARTIALLY-
OBSCURED LLC WITH A BAND OF 20-KNOT WINDS EXTENDING FROM THE SOUTH TO
THE EAST OF THE CENTER AND MOST OF THE CONVECTION SHEARED TO THE
SOUTH. PRESENTLY, ENVIRONMENTAL CONDITIONS ARE SUBOPTIMAL AS A RESULT
OF HIGH VWS (20-30KTS) PRESSING DOWN FROM THE NORTH ALONG THE WESTERN
SIDE OF A STRONG TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) POSITIONED
TO THE NORTH OF 99W. NONETHELESS, THE WARM SSTS (29-30C) AND AMPLE
MOISTURE WILL PROVIDE THE ENERGY TO BEGIN THE DEVELOPMENT PROCESS.
OVER THE NEXT 24 HOURS, THE TUTT WILL WEAKEN AND TRACK NORTHWARD,
POSITIONING 99W IN THE EASTERN, DIFFLUENT REGION, WHICH WILL SUPPLY
SUFFICIENT OUTFLOW TO COUNTERACT THE EFFECTS OF THE VWS. THERE IS A
CONSENSUS ACROSS GLOBAL MODELS THAT CONDITIONS WILL IMPROVE AS INVEST
99W TRACKS TOWARD THE NORTH-NORTHEAST, WHILE THE HIGH VWS SUBSIDES,
ENABLING STEADY DEVELOPMENT OVER THE NEXT 72 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
IS LOW.

[Hayabusa]

ABPW10 PGTW 041330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/041330Z-050600ZSEP2023//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/040753ZSEP2023//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 04SEP23 0600Z, TROPICAL STORM 10W (HAIKUI) WAS LOCATED
NEAR 23.2N 119.3E, APPROXIMATELY 166 NM SOUTHWEST OF TAIPEI, TAIWAN,
AND HAD TRACKED WESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. MAXIMUM
SUSTAINED SURFACE WINDS WERE ESTIMATED AT 60 KNOTS GUSTING TO 75
KNOTS. SEE REF A (WTPN33 PGTW 040900) FOR FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR
20.0N 129.1E IS NOW LOCATED NEAR 21.1N 130.3E, APPROXIMATELY 335 NM
SOUTH-SOUTHEAST OF KADENA, AB. ANIMATED EIR DEPICTS A FAIRLY
DISORGANIZED SYSTEM WITH RAIN BANDS AND SOME CONVECTION BEGINNING TO
CURVE AROUND THE OBSCURED LLC. THIS IS FURTHER EVIDENCED BY A 041111Z
PARTIAL GMI 89GHZ MICROWAVE IMAGE. ENVIRONMENTAL CONDITIONS REMAIN
SUBOPTIMAL AS A RESULT OF HIGH VWS (20-30KTS) PRESSING DOWN FROM THE
NORTH ALONG THE WESTERN SIDE OF A STRONG TROPICAL UPPER TROPOSPHERIC
TROUGH (TUTT) POSITIONED TO THE NORTH OF 99W. NONETHELESS, THE WARM
SSTS (29-30C) AMPLE OHC, AND MOISTURE WILL PROVIDE THE ENERGY TO
CONTINUE THE DEVELOPMENT PROCESS. OVER THE NEXT 24 HOURS, THE TUTT
WILL WEAKEN AND TRACK NORTHWARD, POSITIONING 99W IN THE EASTERN,
DIFFLUENT REGION, WHICH WILL SUPPLY SUFFICIENT OUTFLOW TO COUNTERACT
THE EFFECTS OF THE VWS. THERE IS A CONSENSUS ACROSS GLOBAL MODELS THAT
CONDITIONS WILL IMPROVE AS INVEST 99W TRACKS TOWARD THE NORTHEAST,
WHILE THE HIGH VWS SUBSIDES, ENABLING STEADY DEVELOPMENT OVER THE NEXT
72 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

[Hayabusa]

T2313(Yun-yeung)
Issued at 2023/09/05 13:10 UTC
Analysis at 09/05 12 UTC
Grade TS
Scale -
Intensity -
Center position N22°05′ (22.1°)
E131°30′ (131.5°)
Direction and speed of movement NE Slow
Central pressure 1000 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of 30-kt wind area SE330 km (180 NM)
NW220 km (120 NM)
Forecast for 09/06 12 UTC
Grade TS
Intensity -
Center position of probability circle N28°50′ (28.8°)
E135°25′ (135.4°)
Direction and speed of movement NE 35 km/h (19 kt)
Central pressure 998 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 120 km (65 NM)
Forecast for 09/07 12 UTC
Grade TS
Intensity -
Center position of probability circle N32°50′ (32.8°)
E140°00′ (140.0°)
Direction and speed of movement NE 25 km/h (14 kt)
Central pressure 994 hPa
Maximum sustained wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 210 km (115 NM)
Forecast for 09/08 12 UTC
Grade TS
Intensity -
Center position of probability circle N35°05′ (35.1°)
E142°30′ (142.5°)
Direction and speed of movement NE 15 km/h (8 kt)
Central pressure 994 hPa
Maximum sustained wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 300 km (160 NM)
Forecast for 09/09 12 UTC
Grade TD
Intensity -
Center position of probability circle N37°50′ (37.8°)
E144°35′ (144.6°)
Direction and speed of movement NE 15 km/h (8 kt)
Central pressure 1002 hPa
Radius of probability circle 370 km (200 NM)

[Sciencerocks]

[Sciencerocks]

 https://twitter.com/VortixWx/status/1699098169055883298

[Sciencerocks]

[cycloneye]

WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (YUN-YEUNG)
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 26.5N 134.3E
INITIAL INTENSITY: 35 KTS
GEOGRAPHIC REFERENCE: 596 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 14 KTS
SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC)
POSITIONED UNDER THE NORTHERN EDGE OF AN AREA OF EXPANDING DEEP
CONVECTION. A 060426Z ATMS 88.2 GHZ MICROWAVE IMAGE INDICATES THE
DEEP CONVECTIVE AREA IS NOT WELL-ORGANIZED AND IS LINEAR, SHEARED
TOWARD THE SOUTHWEST. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE MSI. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE CIMSS ADT, AIDT, DPRINT,
AND SATCON ESTIMATES. THE REMNANTS OF 11W (KIROGI), WHICH ARE
CURRENTLY CENTERED ABOUT 322 NM NORTH OF 12W'S INITIAL POSITION, ARE
UNDERGOING BINARY INTERACTION WITH 12W. MSI INDICATES THE REMNANTS OF
11W ARE STILL INTACT BUT ARE BEGINNING TO WEAKEN SIGNIFICANTLY AS THEY
INTERACT WITH THE OUTER PERIPHERY OF 12W AND ACCELERATE SOUTHEASTWARD
TO SOUTHWARD.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK

CURRENT STEERING MECHANISM: PRIMARY: LOW- TO MID-LEVEL SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST. SECONDARY (THROUGH TAU 24): BINARY
INTERACTION WITH THE REMNANTS OF 11W (KIROGI).

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T2.0 - 30 KTS
KNES: T3.0 - 45 KTS
CIMSS SATCON: 36 KTS AT 060447Z
CIMSS ADT: 34 KTS AT 060530Z
CIMSS AIDT: 36 KTS AT 060530Z
CIMSS DPRINT: 36 KTS AT 060700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 12W IS FORECAST TO TRACK
NORTH-NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF THE STR THROUGH
TAU 24. TS 12W WILL QUICKLY ABSORB THE WEAKENING REMNANTS OF 11W
(KIROGI) WITHIN THE NORTHERN AND NORTHWESTERN QUADRANTS. THE BINARY
INTERACTION OR FUJIWARA INTERACTION WILL INTRODUCE SOME UNCERTAINTY IN
THE EXACT TRACK OF TS 12W WITH A SHORT DURATION NORTHWARD TRACK
POSSIBLE BEFORE 12W RESUMES A STEADY NORTH-NORTHEASTWARD TRACK CLOSE
TO THE KANTO PLAIN. POLEWARD OUTFLOW IS EXPECTED TO IMPROVE IN
RESPONSE TO A MIDLATITUDE SHORTWAVE TROUGH CURRENTLY DIGGING OVER
SOUTH KOREA AND WESTERN JAPAN. IN FACT, ANIMATED WATER VAPOR IMAGERY
INDICATES POLEWARD OUTFLOW IS BEGINNING TO EXPAND WITH DEEP CONVECTION
NOW BUILDING OVER THE LLCC. THE IMPROVED ENVIRONMENTAL CONDITIONS WILL
SUPPORT A SHORT (24 TO 36 HOURS) PERIOD OF INTENSIFICATION WITH A PEAK
OF 45-50 KNOTS BY TAU 36. AFTER TAU 36, VERTICAL WIND SHEAR IS
FORECAST TO INCREASE TO 30-40 KNOTS WITH INCREASING DRY AIR
ENTRAINMENT LEADING TO A STEADY WEAKENING TREND AS THE SYSTEM
APPROACHES AND PASSES THE KANTO PLAIN. THE MIDLATITUDE SHORTWAVE
TROUGH IS EXPECTED TO QUICKLY PROPAGATE NORTHEASTWARD WITH THE STR
REBUILDING, WHICH WILL TURN THE SYSTEM EAST-NORTHEASTWARD AFTER TAU 72
WITH DISSIPATION ANTICIPATED BY TAU 96. DUE TO THE LACK OF A RECURVE
MECHANISM AND BAROCLINIC ZONE, A TYPICAL RECURVE SCENARIO WITH EXTRA-
TROPICAL TRANSITION IS UNLIKELY.

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC GUIDANCE SUPPORTS
THIS SCENARIO WITH A DISTINCT SLOW DOWN AND WEAKENING TREND
REFLECTED IN THE 060000Z GFS AND ECMWF ENSEMBLES. ADDITIONALLY, THERE
ARE NO RECURVING SOLUTIONS, REINFORCING THE LACK OF A RECURVE
MECHANISM. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE JTWC FORECAST
TRACK WITH MODEL GUIDANCE SHOWING SOME POTENTIAL FOR THE SYSTEM TO
TRACK CLOSER TO THE KANTO PLAIN REGION. THE 060000Z COAMPS-TC ENSEMBLE
SUPPORTS THE JTWC INTENSITY FORECAST OVER THE NEXT 36 HOURS WITH
MODERATE INTENSIFICATION PROBABILITIES INCREASING TO 70 TO 80 PERCENT.

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