WPAC: CO-MAY - Tropical Depression - Discussion

[Hayabusa]

99W INVEST 250721 1800 20.7N 125.0E WPAC 15 0

[Hayabusa]

This is the one that makes a loop west of Luzon

[mrbagyo]

[Hayabusa]

Euro, Euro AI, and GFS develops this which would bring more rainfall to the Philippines...

[Hayabusa]

06z eps

[Hayabusa]

Already medium

ABPW10 PGTW 221800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/221800Z-230600ZJUL2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/220751ZJUL2025//
REF/B/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/221351ZJUL2025//
NARR//REF A IS A TROPICAL CYCLONE FINAL WARNING. REF B IS A TROPICAL
CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 22JUL25 0600Z, TROPICAL STORM 09W (WIPHA) WAS LOCATED
NEAR 20.3N 106.2E, APPROXIMATELY 45 NM SOUTH-SOUTHEAST OF HANOI,
VIETNAM, AND HAD TRACKED WEST-SOUTHWESTWARD AT 06 KNOTS OVER THE PAST
SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 35 KNOTS
GUSTING TO 45 KNOTS. SEE REF A (WTPN31 PGTW 220900) FOR THE FINAL
WARNING ON THIS SYSTEM.
(2) AT 22JUL25 1200Z, TROPICAL DEPRESSION 10W (TEN) WAS LOCATED
NEAR 19.6N 131.6E, APPROXIMATELY 464 NM SOUTH-SOUTHEAST OF KADENA AB,
AND HAD TRACKED NORTH-NORTHWESTWARD AT 19 KNOTS OVER THE PAST SIX
HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 25 KNOTS
GUSTING TO 35 KNOTS. SEE REF B (WTPN32 PGTW 221500) FOR FURTHER
DETAILS.
(3) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 98W) PREVIOUSLY LOCATED NEAR
8.5N 154.0E IS NOW LOCATED NEAR 10.7N 151.1E, APPROXIMATELY 408 NM
NORTH-NORTHWEST OF GUAM. MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS A POORLY ORGANIZED LOW LEVEL CIRCULATION CENTER (LLCC) WITH
CYCLING OF DEEP CONVECTION SOUTH SOUTH-EAST. A 202355Z ASCAT PASS
DEPICTS THE STRONGEST WINDS (20-25 KTS) ISOLATED TO THE NORTHWEST.
ENVIRONMENTAL ANALYSIS FOR THE AREA INDICATES FAVORABLE CONDITIONS
WITH LOW VERTICAL WIND SHEAR (10-15 KTS) ACCOMPANIED BY WARM (30C)
SEA SURFACE TEMPERATURES AND MODERATE EQUATORWARD OUTFLOW ALOFT.
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 98W WILL CONTINUE NORTH AS
IT GRADUALLY INTENSIFIES OVER THE NEXT 48 HOURS. ENSEMBLE GUIDANCE
AGREES ON A NORTHWARD TRACK WITH GEFS BEING MORE AGGRESSIVE ON
DEVELOPMENT THAN ECENS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED
AT 13 TO 18 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR
1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.
(2) AN AREA OF CONVECTION (INVEST 99W) HAS PERSISTED NEAR 19.2N
121.8E, APPROXIMATELY 52 NM NORTH OF APARRI, PHILIPPINES. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN OBSCURED LOW
LEVEL CIRCULATION (LLC) WITH PERSISTENT CONVECTION OVER THE CENTER. A
RECENT 221313Z ASCAT-B PASS SHOWS AN ELONGATED CIRCULATION WITH 15-20
KNOTS ALONG THE NORTHWESTERN PERIPHERY OF THE LLC. ENVIRONMENTAL
ANALYSIS REVEALS A MARGINAL ENVIRONMENT FOR DEVELOPMENT WITH LOW TO
MODERATE VERTICAL WIND SHEAR (VWS) OF 15-20 KNOTS, WEAK UPPER-LEVEL
OUTFLOW, AND WARM SEA SURFACE TEMPERATURES (SST) OF 29-30C.
DETERMINISTIC AND ENSEMBLE MODELS ARE SPLIT ON DEVELOPMENT
CONFIDENCE. SOME DETERMINISTIC MODELS FORECAST A BROAD CIRCULATION,
WHILE GFS DEPICTS A SYMMETRIC, STRONGER CIRCULATION, WITH A TIGHT
GRADIENT OF 30-40 KNOTS OVER THE NEXT 24 TO 48 HOURS. THE GEFS
ENSEMBLE INDICATES LOW TRACK CONFIDENCE AMONG ITS MEMBERS, WHILE THE
ECENS ENSEMBLE SHOWS HIGHER CONFIDENCE WITH TIGHTER AGREEMENT ON THE
SYSTEM’S TRACK. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15
TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS MEDIUM.
(3) NO OTHER SUSPECT AREAS.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: ADDED MEDIUM AREA IN PARA. 1.B.(2).//
NNNN

[Hayabusa]

Synoptic stations near 99W, Basco and Calayan are reporting (based on 1900z hourly report) below 1000 mb MSLP

SNPH20 RPMM 221900
AAXX 22191
98133 41430 82405 10263 20257 39959 49974 5//// 76366
8652/ 333 56599 86618 88458 =
98134 41459 8//// 10257 20250 39802 49987 5//// 72582
8457/ 333 56999 84618 88357 =

[Hayabusa]

12z

[Hayabusa]

TCFA

WTPN21 PGTW 222130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
110 NM EITHER SIDE OF A LINE FROM 19.9N 121.5E TO 15.9N 119.5E
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 20 TO 25 KNOTS. METSAT
IMAGERY AT 222130Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 19.4N 121.5E. THE SYSTEM IS MOVING WESTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED
NEAR 19.2N 121.8E IS NOW LOCATED NEAR 19.4N 121.5E, APPROXIMATELY
65 NM NORTH OF APARRI, PHILIPPINES. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION
(LLC) WITH PERSISTENT CENTRAL CONVECTION OVER THE CENTER. ANIMATED RADAR
IMAGERY AND A 221941Z SSMIS 91GHZ MICROWAVE IMAGE DEPICT IMPROVED CURVED
CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW LEVEL CIRCULATION CENTER
(LLCC). RECENT OBSERVATIONS FROM CALAYAN, PHILIPPINES INDICATE A
SIGNIFICANT 24-HOUR SLP DECREASE OF 7 MB FROM 1004MB TO 997MB WITH
SUSTAINED SOUTHWESTERLY WINDS OF 12 KNOTS. ENVIRONMENTAL ANALYSIS
REVEALS A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW VERTICAL WIND
SHEAR (VWS) OF 5-10 KNOTS, GOOD EQUATORWARD UPPER-LEVEL OUTFLOW AND
EASTWARD OUTFLOW, AND WARM SEA SURFACE TEMPERATURES (SST) OF 29-31C.
DETERMINISTIC MODELS HAVE COME INTO BETTER ALIGNMENT SHOWING WINDS OF
30-40 KNOTS WRAPPING AROUND THE LLC IN THE NEXT 24-36 HOURS. AVAILABLE
MODEL GUIDANCE SHOWS A SOUTHWARD TRACK ALONG THE WESTERN COAST OF LUZON.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 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
232130Z.//
NNNN

[ElectricStorm]

18z GFS develops this very quickly and gets to 978mb before landfall in western Luzon. We'll see if this tries to pull a fast one if it can stay over water or not. Looks pretty good though on satellite right now.

[Hayabusa]

upgraded

11W ELEVEN 250723 0000 18.8N 120.5E WPAC 30 997

[ElectricStorm]

WTPN33 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 11W (ELEVEN) WARNING NR 001//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/222121ZJUL2025//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. TROPICAL DEPRESSION 11W (ELEVEN) WARNING NR 001
03 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
230000Z --- NEAR 18.8N 120.5E
MOVEMENT PAST SIX HOURS - 240 DEGREES AT 10 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND RADAR
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 18.8N 120.5E
---
FORECASTS:
12 HRS, VALID AT:
231200Z --- 17.8N 119.1E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 205 DEG/ 04 KTS
---
24 HRS, VALID AT:
240000Z --- 17.0N 118.7E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 085 DEG/ 07 KTS
---
36 HRS, VALID AT:
241200Z --- 17.1N 120.1E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
010 NM SOUTHEAST QUADRANT
010 NM SOUTHWEST QUADRANT
010 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 045 DEG/ 11 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
250000Z --- 18.7N 121.7E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
000 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 030 DEG/ 13 KTS
---
72 HRS, VALID AT:
260000Z --- 23.2N 124.6E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
230300Z POSITION NEAR 18.5N 120.1E.
23JUL25. TROPICAL DEPRESSION 11W (ELEVEN), LOCATED APPROXIMATELY
254 NM NORTH OF MANILA, PHILIPPINES, HAS TRACKED WEST-
SOUTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL
PRESSURE AT 230000Z IS 997 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
230000Z IS 14 FEET. NEXT WARNINGS AT 230900Z, 231500Z, 232100Z AND
240300Z. REFER TO TROPICAL DEPRESSION 09W (WIPHA) FINAL WARNING
(WTPN31 PGTW). REFER TO TROPICAL STORM 10W (TEN) WARNINGS
(WTPN32 PGTW) FOR SIX-HOURLY UPDATES.
2. THIS CANCELS AND SUPERSEDES REF A (WTPN21 PGTW 222130).//
NNNN

[mrbagyo]

Escalated so quickly

[Hayabusa]

TD a
Issued at 2025/07/23 07:15 UTC
Analysis at 07/23 06 UTC
Grade TD
Scale -
Intensity -
Center position N18°05′ (18.1°)
E119°35′ (119.6°)
Direction and speed of movement WSW 15 km/h (7 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 07/23 18 UTC
Grade TS
Intensity -
Center position of probability circle N17°25′ (17.4°)
E118°20′ (118.3°)
Direction and speed of movement WSW 15 km/h (7 kt)
Central pressure 994 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 100 km (55 NM)
Forecast for 07/24 06 UTC
Grade TS
Intensity -
Center position of probability circle N16°40′ (16.7°)
E118°35′ (118.6°)
Direction and speed of movement SSE Slow
Central pressure 990 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 130 km (70 NM)
Forecast for 07/25 06 UTC
Grade TS
Intensity -
Center position of probability circle N19°20′ (19.3°)
E122°40′ (122.7°)
Direction and speed of movement ENE 20 km/h (12 kt)
Central pressure 994 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 240 km (130 NM)
Forecast for 07/26 06 UTC
Grade TD
Intensity -
Center position of probability circle N21°10′ (21.2°)
E125°50′ (125.8°)
Direction and speed of movement ENE 15 km/h (9 kt)
Central pressure 998 hPa
Radius of probability circle 350 km (190 NM)

[mrbagyo]

Looks like it has surpassed TD status by a lot heck, TS might be a little conservative in a few hours from now

[Hayabusa]

WTPQ50 ‎RJTD ‎231200
RSMC ‎TROPICAL ‎CYCLONE ‎ADVISORY
NAME ‎ ‎TS ‎2508 ‎CO-MAY ‎(2508) ‎UPGRADED ‎FROM ‎TD
ANALYSIS
PSTN ‎ ‎231200UTC ‎17.7N ‎118.8E ‎FAIR
MOVE ‎ ‎W ‎08KT
PRES ‎ ‎994HPA
MXWD ‎ ‎035KT
GUST ‎ ‎050KT
30KT ‎ ‎90NM
FORECAST
12HF ‎ ‎240000UTC ‎16.9N ‎118.6E ‎40NM ‎70%
MOVE ‎ ‎S ‎SLOWLY
PRES ‎ ‎990HPA
MXWD ‎ ‎040KT
GUST ‎ ‎060KT
24HF ‎ ‎241200UTC ‎16.4N ‎119.1E ‎57NM ‎70%
MOVE ‎ ‎SE ‎SLOWLY
PRES ‎ ‎980HPA
MXWD ‎ ‎050KT
GUST ‎ ‎070KT
48HF ‎ ‎251200UTC ‎20.3N ‎123.2E ‎100NM ‎70%
MOVE ‎ ‎NE ‎14KT
PRES ‎ ‎994HPA
MXWD ‎ ‎035KT
GUST ‎ ‎050KT
72HF ‎ ‎261200UTC ‎25.4N ‎129.6E ‎160NM ‎70% ‎TROPICAL ‎DEPRESSION ‎=

[mrbagyo]

[cycloneye]

FORECAST DISCUSSION: TS 11W WILL CURVE IN A CYCLONIC DIRECTION OVER
THE NEXT 24 HOURS WHILE IN A COMPLEX AND WEAK STEERING ENVIRONMENT
BETWEEN THE ENHANCED MONSOONAL FLOW ASSOCIATED WITH THE LARGE-SCALE
LOW TO THE NORTH AND WEAK RIDGING TO THE SOUTHEAST. THE SYSTEM WILL
TRACK NORTHEASTWARD AFTER TAU 24, PASSING OVER NORTHERN LUZON AT
TAU 36, AND CONTINUE FOR THE REMAINDER OF THE FORECAST.
INTENSIFICATION WILL CONTINUE FOR THE NEXT 24 HOURS WHILE IN A
FAVORABLE ENVIRONMENT WITH STRONG UPPER-LEVEL DIVERGENCE, WARM SEA
SURFACE TEMPERATURES AND LOW VERTICAL WIND SHEAR. WEAKENING WILL
OCCUR AFTER THE SYSTEM INTERACTS WITH THE TOPOGRAPHY OF NORTHERN
LUZON, AND BEGIN DISSIPATING INTO THE LARGER MONSOONAL FLOW FROM
TAU 36-48.

[cycloneye]

 https://x.com/mscuyugan/status/1948026593647153575

[cycloneye]

Looks like it continues to do the RI.