WPAC: KIROGI - Post-Tropical

[Hayabusa]

94W INVEST 230827 1800 5.6N 161.5E WPAC 15 0

[Hayabusa]

Now low

ABPW10 PGTW 290230
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/290230Z-290600ZAUG2023//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/281953ZAUG2023//
REF/B/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/281952ZAUG2023//
REF/C/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/280751ZAUG2023//
NARR/REFS A AND B ARE TROPICAL CYCLONE WARNINGS. REF C IS A TROPICAL
CYCLONE FINAL WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 28AUG23 1800Z, TROPICAL STORM 10W (HAIKUI) WAS LOCATED
NEAR 18.6N 139.6E, APPROXIMATELY 386NM SOUTH-SOUTHWEST OF IWO TO, AND
HAD TRACKED WESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. MAXIMUM
SUSTAINED SURFACE WINDS WERE ESTIMATED AT 35 KNOTS GUSTING TO 45
KNOTS. SEE REF A (WTPN33 PGTW 282100) FOR FURTHER DETAILS.
(2) AT 28AUG23 1800Z, TYPHOON 09W (SAOLA) WAS LOCATED NEAR 18.3N
123.9E, APPROXIMATELY 278 NM NORTHEAST OF MANILA, PHILIPPINES, AND HAD
TRACKED NORTH- NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS.
MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 100 KNOTS GUSTING TO
125 KNOTS. SEE REF B (WTPN32 PGTW 282100) FOR FURTHER DETAILS.
(3) AT 28AUG23 0600Z, TROPICAL STORM 08W (DAMREY) WAS LOCATED
NEAR 39.9N 145.6E, APPROXIMATELY 204 NM EAST OF MISAWA, JAPAN, AND HAD
TRACKED NORTH-NORTHEASTWARD AT 17 KNOTS OVER THE PAST SIX HOURS.
MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 45 KNOTS GUSTING TO
55 KNOTS. SEE REF C (WTPN31 PGTW 280900) FOR THE FINAL WARNING ON THIS
SYSTEM.
(4) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 94W) HAS PERSISTED NEAR 9.6N
158.3E, APPROXIMATELY 147 NM WEST OF THE UJELANG ATOLL. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY AND A PARTIAL 282317Z ASCAT METOP-B
DEPICTS A BROAD CENTER OF BUILDING CONVECTION OVER A FULLY OBSCURED
CIRCULATION WITH 15 KNOT WINDS TO THE NORTH EAST. UPPER LEVEL ANALYSIS
INDICATES THAT 94W IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH
MODERATE VERTICAL WIND SHEAR (15-20 KTS), DIVERGENCE ALOFT, DUAL
CHANNEL UPPER AIR OUTFLOW TO THE NORTH EAST AND SOUTH, WITH WARM SEA
SURFACE TEMPERATURES (30C). GLOBAL MODELS ARE IN GOOD AGREEMENT THAT
94W WILL CONTINUE TO TRACK NORTHEAST AND DEVELOP OVER THE NEXT 48
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO 17
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS LOW.

[Hayabusa]

Up to medium

ABPW10 PGTW 291330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/291330Z-300600ZAUG2023//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/290753ZAUG2023//
REF/B/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/290752ZAUG2023//
NARR/REFS A AND B ARE TROPICAL CYCLONE WARNINGS.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 29AUG23 0600Z, TROPICAL STORM 10W (HAIKUI) WAS LOCATED
NEAR 19.0N 137.2E, APPROXIMATELY 416 NM SOUTHWEST OF IWO TO, AND HAD
TRACKED WESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. MAXIMUM
SUSTAINED SURFACE WINDS WERE ESTIMATED AT 55 KNOTS GUSTING TO 70
KNOTS. SEE REF A (WTPN33 PGTW 290900) FOR FURTHER DETAILS.
(2) AT 29AUG23 0600Z, TYPHOON 09W (SAOLA) WAS LOCATED NEAR
18.9N 123.1E, APPROXIMATELY 285 NM NORTH-NORTHEAST OF MANILA,
PHILIPPINES, AND HAD TRACKED NORTHWESTWARD AT 05 KNOTS OVER THE PAST
SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 120
KNOTS GUSTING TO 145 KNOTS. SEE REF B (WTPN32 PGTW 290900) FOR
FURTHER DETAILS.
(3) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED NEAR
9.6N 158.3E IS NOW LOCATED NEAR 11.1N 154.7E, APPROXIMATELY 597 NM
EAST OF ANDERSEN AFB. ANIMATED MULTISPECTRAL INFRARED IMAGERY AND A
291151Z GMI 91GHZ MICROWAVE PASS DEPICT DEEP CONVECTIVE LINES ON THE
EAST- AND WESTERN FLANKS, WRAPPING INTO A MOSTLY OBSCURED LOW LEVEL
CIRCULATION CENTER (LLCC). A 290130Z SCATTEROMETRY PASS REVEALED 15-
20KT WINDS SURROUNDING AN ELONGATED AREA OF ROTATION. ENVIRONMENTAL
ANALYSIS REVEALS A FAVORABLE CONDITIONS FOR INTENSIFICATION DUE TO
LOW (10-15KT) VWS, WARM (30C) SSTS, AND GOOD POLEWARD AND EQUATORWARD
OUTFLOW. MODELS AGREE THAT 94W WILL INTENSIFY ALONG A NORTHERLY TRACK
BEFORE RECURVING TO THE NORTHWEST AROUND THE NORTHERN MARIANAS
ISLANDS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

[Hayabusa]

Eps 06z

[Hayabusa]

TD b
Issued at 2023/08/29 13:25 UTC
Analysis at 08/29 12 UTC
Grade TD
Scale -
Intensity -
Center position N11°10′ (11.2°)
E156°40′ (156.7°)
Direction and speed of movement WNW Slow
Central pressure 1006 hPa
Maximum wind speed 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 08/30 12 UTC
Grade TS
Intensity -
Center position of probability circle N13°35′ (13.6°)
E153°50′ (153.8°)
Direction and speed of movement NW 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 08/31 12 UTC
Grade TS
Intensity -
Center position of probability circle N17°55′ (17.9°)
E152°05′ (152.1°)
Direction and speed of movement NNW 20 km/h (12 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 09/01 12 UTC
Grade TS
Intensity -
Center position of probability circle N22°20′ (22.3°)
E148°10′ (148.2°)
Direction and speed of movement NW 25 km/h (14 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 260 km (140 NM)
Forecast for 09/02 12 UTC
Grade TS
Intensity -
Center position of probability circle N27°25′ (27.4°)
E143°10′ (143.2°)
Direction and speed of movement NW 30 km/h (17 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 330 km (180 NM)
Forecast for 09/03 12 UTC
Grade TS
Intensity -
Center position of probability circle N30°10′ (30.2°)
E135°00′ (135.0°)
Direction and speed of movement WNW 35 km/h (19 kt)
Central pressure 998 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 440 km (240 NM)

[Hayabusa]

TCFA

WTPN21 PGTW 291800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 94W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 10.9N 155.4E TO 15.1N 151.1E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 18 TO 23 KNOTS. METSAT
IMAGERY AT 291200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 11.1N 154.7E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 10
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED
NEAR 11.1N 154.7E IS NOW LOCATED NEAR 11.0N 153.6E, APPROXIMATELY
541 NM EAST-SOUTHEAST OF GUAM. ANIMATED PROXYVIS SATELLITE IMAGERY
DEPICTS A MOSTLY OBSCURED LLCC ENVELOPED BY PERSISTENT CONVECTION, WHICH
IS FURTHER EVIDENT IN A 291508Z AMSR-2 89GHZ MICROWAVE IMAGE.
ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR INTENSIFICATION
DUE TO LOW (10-15KT) VWS, WARM (30C) SSTS, AND GOOD POLEWARD AND
EQUATORWARD OUTFLOW. GLOBAL MODELS AGREE THAT 94W WILL INTENSIFY AS IT
FOLLOWS A NORTHWESTWARD TRACK OVER THE NEXT FEW DAYS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
301800Z.
//
NNNN

[ElectricStorm]

JTWC upgraded to 11W. First forecast 60kt peak

[LemieT]

JTWC upgraded to 11W. First forecast 60kt peak

Based just on imagery it looks like it wants to develop very quickly.

[Hayabusa]

00Z

[Hayabusa]

T2312(Kirogi)
Issued at 2023/08/30 13:25 UTC
Analysis at 08/30 12 UTC
Grade TS
Scale -
Intensity -
Center position N13°20′ (13.3°)
E154°20′ (154.3°)
Direction and speed of movement NNW 10 km/h (6 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 30-kt wind area 220 km (120 NM)
Forecast for 08/31 12 UTC
Grade TS
Intensity -
Center position of probability circle N17°30′ (17.5°)
E152°30′ (152.5°)
Direction and speed of movement NNW 20 km/h (11 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 120 km (65 NM)
Forecast for 09/01 12 UTC
Grade STS
Intensity -
Center position of probability circle N22°10′ (22.2°)
E148°25′ (148.4°)
Direction and speed of movement NW 30 km/h (15 kt)
Central pressure 990 hPa
Maximum sustained wind speed near center 30 m/s (55 kt)
Maximum wind gust speed 40 m/s (80 kt)
Radius of probability circle 210 km (115 NM)
Radius of storm warning area 250 km (135 NM)
Forecast for 09/02 12 UTC
Grade TS
Intensity -
Center position of probability circle N26°05′ (26.1°)
E142°35′ (142.6°)
Direction and speed of movement NW 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 300 km (160 NM)
Forecast for 09/03 12 UTC
Grade TD
Intensity -
Center position of probability circle N28°25′ (28.4°)
E135°30′ (135.5°)
Direction and speed of movement WNW 30 km/h (17 kt)
Central pressure 1000 hPa
Radius of probability circle 370 km (200 NM

[Sciencerocks]

[cycloneye]

WDPN31 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KIROGI)
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 14.1N 154.5E
INITIAL INTENSITY: 45 KTS
GEOGRAPHIC REFERENCE: 560 NM EAST OF ANDERSEN AFB, GUAM
MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CENTRAL DENSE OVERCAST (CDO) FEATURE OBSCURING THE LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH A CONVECTIVE BAND OVER THE NORTHERN
SEMICIRCLE. A 301807Z SSMIS 91 GHZ COLOR COMPOSITE MICROWAVE IMAGE
INDICATES A COMPACT SYSTEM WITH CONVECTIVE BANDING WRAPPING INTO A
SMALL, WELL-ORGANIZED CORE. THE CONVECTIVE BANDING WITHIN THE CORE
WRAPS INTO A WELL-DEFINED LLCC, WHICH SUPPORTS THE INITIAL POSITION
WITH HIGH CONFIDENCE. ANIMATED WATER VAPOR IMAGERY AND CIMSS MID-UPPER
LEVEL WINDS IMAGERY SHOW AN UPPER-LOW AND DEEP TROUGH WEST AND
NORTHWEST OF THE SYSTEM. DESPITE SOME PRESSURE ON THE WESTERN
PERIPHERY, THIS TROUGH IS BOOSTING POLEWARD OUTFLOW AND AIDING IN THE
RECENT INTENSIFICATION AND CONSOLIDATION OF THE SYSTEM. THE INITIAL
INTENSITY OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
PGTW, KNES DVORAK ESTIMATES AS WELL AS THE CIMSS ADT ESTIMATE AND A
301700Z DPRINT ESTIMATE OF 43 KNOTS. ADDITIONALLY, A 301549Z AMSR2
WINDSPEED IMAGE REVEALS A SWATH OF 40-50 KNOT WINDS OVER THE NORTHERN
SEMICIRCLE WITH A PATCH OF 50-60 KNOT WINDS (UNDER DEEP CONVECTIVE
BURST) OVER THE NORTHERN QUADRANT.

INITIAL WIND RADII BASIS: AMSR2 WINDSPEED DATA

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.0 - 45 KTS
RJTD: T2.0 - 30 KTS
RCTP: T2.5 - 35 KTS
KNES: T3.0 - 45 KTS
CIMSS ADT: 45 KTS AT 301740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 15-20 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 11W IS FORECAST TO GRADUALLY
TURN NORTHWESTWARD AS IT TRANSITIONS TO THE STEERING INFLUENCE OF A
STRONG STR POSITIONED TO THE NORTH. TS 11W WILL CONTINUE TRACKING
NORTHWESTWARD TO WEST-NORTHWESTWARD THROUGH THE FORECAST PERIOD. DUE
TO FAVORABLE CONDITIONS THROUGH TAU 24 AND THE COMPACT NATURE OF THE
SYSTEM, TS 11W WILL INTENSIFY TO 60 KNOTS BY TAU 24. AFTER TAU 24, THE
SYSTEM IS FORECAST TO TRACK UNDER THE EASTERN PERIPHERY OF THE UPPER
LOW, WITH INCREASING VERTICAL WIND SHEAR (VWS), WHICH WILL LEAD TO A
STEADY WEAKENING TREND. THE UPPER LOW WILL CONTINUE TO TRACK WESTWARD
ALONG WITH THE SYSTEM WITH STRONG VWS AND WEAK DIVERGENCE PERSISTING
THROUGH THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72 WITH A 130 NM SPREAD IN SOLUTIONS AT TAU 72. AFTER TAU
72, GUIDANCE DIVERGES TO 300 NM AT TAU 120 LENDING MEDIUM CONFIDENCE
TO THE JTWC EXTENDED TRACK FORECAST. COAMPS-TC AND HAFS-A INTENSITY
GUIDANCE INDICATES A PEAK OF 55 TO 60 KNOTS AT TAU 24. THE JTWC
INTENSITY CONSENSUS (ICNW) PEAKS SLIGHTLY LOWER AT 53 KNOTS DUE TO
DECAY SHIPS (NAVGEM AND GFS VERSIONS), WHICH ARE PEAKING AT ABOUT 47
KNOTS. AFTER TAU 36, INTENSITY GUIDANCE GENERALLY SHOWS A STEADY
WEAKENING TREND AND LARGER SPREAD, ESPECIALLY IN THE EXTENDED PERIOD
WITH LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST.

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

[cycloneye]

11W KIROGI 230831 1200 18.3N 153.7E WPAC 55 993

[Sciencerocks]