Tropical Depression SEPAT: Discussions, Analysis and Image

[Chacor]

WTPN31 PGTW 120900
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC/
REF/A/NAVPACMETOCCEN PEARL HARBOR HI/111951Z AUG 07//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. TROPICAL DEPRESSION 09W WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
---
WARNING POSITION:
120600Z --- NEAR 17.4N 135.6E
MOVEMENT PAST SIX HOURS - 270 DEGREES AT 01 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 17.4N 135.6E
---
FORECASTS:
12 HRS, VALID AT:
121800Z --- 17.4N 135.2E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 270 DEG/ 03 KTS
---
24 HRS, VALID AT:
130600Z --- 17.4N 134.5E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 270 DEG/ 05 KTS
---
36 HRS, VALID AT:
131800Z --- 17.4N 133.5E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 275 DEG/ 07 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
140600Z --- 17.5N 132.0E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
085 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 280 DEG/ 08 KTS
---
72 HRS, VALID AT:
150600Z --- 18.0N 128.8E
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
100 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
---
REMARKS:
120900Z POSITION NEAR 17.4N 135.5E.
TROPICAL DEPRESSION 09W (NONAME) LOCATED APPROXIMATELY 685 NM
SOUTHEAST OF NAHA, OKINAWA, HAS REMAINED QUASISTATIONARY OVER THE
PAST 06 HOURS. RECENT DVORAK SATELLITE INTENSITY ESTIMATES AND A
120110Z ASCAT PASS SUPPORT AN INITIAL WARNING INTENSITY OF 30
KNOTS. THE SYSTEM IS CURRENTLY IN A WEAK STEERING ENVIRONMENT
BETWEEN NEAR-EQUATORIAL RIDGING TO THE SOUTHWEST AND SUBTROPICAL
RIDGING TO THE NORTHEAST. THE STORM IS FORECAST TO REMAIN NEARLY
STATIONARY FOR THE NEXT 24 HOURS BEFORE SUBTROPICAL RIDGING
BUILDS TO THE NORTH, ALLOWING THE SYSTEM TO ACCELERATE WESTWARD.
THE COMPETING INFLUENCES OF MODERATE VERTICAL WIND SHEAR AND
GOOD UPPER LEVEL DIFFLUENCE SHOULD RESULT IN SLOW BUT STEADY
INTENSIFICATION DURING THE FORECAST PERIOD. THIS WARNING SUPER-
SEDES AND CANCELS REF A, NAVPACMETOCCEN 111951Z AUG 07 TROPICAL
CYCLONE FORMATION ALERT (WTPN21 PGTW 112000) MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 120600Z IS 10 FEET. NEXT WARNINGS AT 121500Z,
122100Z, 130300Z AND 130900Z.//

WTPQ20 RJTD 120600
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 120600UTC 17.3N 135.6E FAIR
MOVE ALMOST STATIONARY
PRES 1004HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 130600UTC 17.1N 135.0E 150NM 70%
MOVE ALMOST STATIONARY
PRES 998HPA
MXWD 035KT
GUST 050KT =

[Chacor]

Original thread: viewtopic.php?f=31&t=96877

[WindRunner]

Well, I'm glad they got one out of three of these "depressions" going . . . this one should be interesting to watch, at least . . .

[Typhoon Hunter]

Yes, this one will be very interesting to watch. The latest ECMWF run for this system is a sight with a massive strike on Taiwan:

[P.K.]

Still forecasting TS strength within 12 hours.

FKPQ30 RJTD 121200
TC ADVISORY
DTG: 20070812/1200Z
TCAC: TOKYO
TC: TD
NR: 2
PSN: N1705 E13525
MOV: S SLOWLY
C: 1006HPA
MAX WIND: 30KT
FCST PSN +12HR: 13/0000Z N1655 E13455
FCST MAX WIND +12HR: 35KT
FCST PSN +18HR: NIL
FCST MAX WIND +18HR: NIL
FCST PSN +24HR: 13/1200Z N1700 E13405
FCST MAX WIND +24HR: 35KT
NXT MSG: 20070812/1800Z =

[Chacor]

JTWC have upgraded to a 40-kt TS.

[P.K.]

T2.5 at 1800 and upgraded to 0708.

RSMC TROPICAL CYCLONE ADVISORY
NAME TS 0708 SEPAT (0708) UPGRADED FROM TD
ANALYSIS
PSTN 121800UTC 16.9N 135.2E POOR
MOVE ALMOST STATIONARY
PRES 1002HPA
MXWD 035KT
GUST 050KT
30KT 90NM
FORECAST
24HF 131800UTC 17.2N 133.8E 80NM 70%
MOVE W SLOWLY
PRES 996HPA
MXWD 040KT
GUST 060KT
48HF 141800UTC 17.3N 132.9E 150NM 70%
MOVE ALMOST STATIONARY
PRES 990HPA
MXWD 045KT
GUST 065KT
72HF 151800UTC 17.7N 130.6E 220NM 70%
MOVE W 06KT
PRES 985HPA
MXWD 050KT
GUST 070KT =

[RL3AO]

Can someone change the name of the thread to Tropical Storm Sepat?

[RL3AO]

50 kts or so

[Typhoon Hunter]

Up to 40kts now. JMA calling for typhoon status within 72 hours:

TS 0708 (SEPAT)
Issued at 00:00 UTC, 13 August 2007RSMC TROPICAL CYCLONE ADVISORY
NAME TS 0708 SEPAT (0708)

ANALYSIS
PSTN 130000UTC 16.9N 134.5E FAIR
MOVE W 06KT
PRES 996HPA
MXWD 040KT
GUST 060KT
30KT 100NM

FORECAST
24HF 140000UTC 17.4N 132.3E 80NM 70%
MOVE W SLOWLY
PRES 985HPA
MXWD 050KT
GUST 070KT
48HF 150000UTC 17.8N 130.4E 150NM 70%
MOVE W SLOWLY
PRES 975HPA
MXWD 060KT
GUST 085KT
72HF 160000UTC 18.2N 127.9E 220NM 70%
MOVE W 06KT
PRES 965HPA
MXWD 070KT
GUST 100KT

ECMWF is still calling for a large hit on Taiwan.

[wxmann_91]

FWIW, 12Z ECMWF

[P.K.]

T3.5 from RSMC Tokyo at 0600.

[Chacor]

WTJP21 RJTD 130600
WARNING 130600.
WARNING VALID 140600.
WARNING IS UPDATED EVERY 6 HOURS.
STORM WARNING.
SEVERE TROPICAL STORM 0708 SEPAT (0708) UPGRADED FROM TROPICAL STORM
985 HPA
AT 16.6N 133.8E SEA EAST OF PHILIPPINES MOVING WESTSOUTHWEST 07
KNOTS.
POSITION GOOD.
MAX WINDS 50 KNOTS NEAR CENTER.
RADIUS OF OVER 30 KNOT WINDS 150 MILES SOUTHWEST SEMICIRCLE AND 80
MILES ELSEWHERE.
FORECAST POSITION FOR 140600UTC AT 17.1N 131.6E WITH 80 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
980 HPA, MAX WINDS 55 KNOTS NEAR CENTER.
EXTENDED OUTLOOK.
FORECAST POSITION FOR 150600UTC AT 17.5N 129.9E WITH 150 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
970 HPA, MAX WINDS 65 KNOTS NEAR CENTER.
FORECAST POSITION FOR 160600UTC AT 18.0N 127.5E WITH 220 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
965 HPA, MAX WINDS 70 KNOTS NEAR CENTER.

JAPAN METEOROLOGICAL AGENCY.=

[wxmann_91]

Eye is developing...

[RL3AO]

This fellow picked a bad time to develop...no attention from us Westerners.

[P.K.]

T4.0 from RSMC Tokyo at 1800, up from T3.5 six hours ago.

[P.K.]

RSMC TROPICAL CYCLONE ADVISORY
NAME STS 0708 SEPAT (0708)
ANALYSIS
PSTN 132100UTC 16.4N 132.0E GOOD
MOVE W 06KT
PRES 980HPA
MXWD 060KT
GUST 085KT
50KT 50NM
30KT 170NM SOUTHWEST 80NM NORTHEAST
FORECAST
24HF 142100UTC 16.4N 129.6E 80NM 70%
MOVE W 06KT
PRES 970HPA
MXWD 065KT
GUST 095KT
45HF 151800UTC 17.8N 128.1E 150NM 70%
MOVE WNW SLOWLY
PRES 965HPA
MXWD 070KT
GUST 100KT
69HF 161800UTC 19.7N 126.0E 220NM 70%
MOVE NW 07KT
PRES 960HPA
MXWD 075KT
GUST 105KT

[HURAKAN]

Typhoon Sepat sounds right!!!

[btangy]

I would watch for some very rapid intensification soon. Upper level divergence is phenomenal over Sepat aided by a very strong jet off to its W and SW and the ambient environment is quite moist. Still some N shear over it, but if it abates, watch out.

[Chacor]

TY 0708 (SEPAT)
Issued at 00:00 UTC, 14 August 2007
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 0708 SEPAT (0708) UPGRADED FROM STS
ANALYSIS
PSTN 140000UTC 16.4N 131.6E GOOD
MOVE W 07KT
PRES 965HPA
MXWD 070KT
GUST 100KT
50KT 60NM
30KT 170NM
FORECAST
24HF 150000UTC 16.5N 129.8E 80NM 70%
MOVE W SLOWLY
PRES 955HPA
MXWD 075KT
GUST 105KT
48HF 160000UTC 17.7N 128.1E 150NM 70%
MOVE NW SLOWLY
PRES 950HPA
MXWD 080KT
GUST 115KT
72HF 170000UTC 20.5N 125.3E 220NM 70%
MOVE NW 10KT
PRES 950HPA
MXWD 080KT
GUST 115KT