Tropical Depression SEPAT: Discussions, Analysis and Image

[Ptarmigan]

I saw forecast for this typhoon and it will strengthen into a Category 5 hurricane. You don't see that a lot. It does look like Wilma from 2005. Of course, no one has flown in and we have to relie on the Dvorak Technique which is not 100% accurate. That was shown with Wilma and Hugo.

[wxmann_91]

The JTWC's cone includes wind radii.

That's what I hypothesized. Thanks.

Another image

[Chacor]

TY 0708 (SEPAT)
Issued at 03:00 UTC, 15 August 2007
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 0708 SEPAT (0708)
ANALYSIS
PSTN 150300UTC 15.6N 128.4E GOOD
MOVE W SLOWLY
PRES 935HPA
MXWD 095KT
GUST 135KT
50KT 80NM
30KT 170NM
FORECAST
24HF 160300UTC 17.0N 127.0E 80NM 70%
MOVE NW SLOWLY
PRES 930HPA
MXWD 100KT
GUST 140KT
45HF 170000UTC 20.3N 125.1E 150NM 70%
MOVE NNW 10KT
PRES 930HPA
MXWD 100KT
GUST 140KT
69HF 180000UTC 23.3N 121.9E 220NM 70%
MOVE NW 11KT
PRES 945HPA
MXWD 085KT
GUST 120KT

BTW that area of convection near Hong Kong is now INVEST 97W and is a TD from the JMA.

[DESTRUCTION5]

SEPAT (he/she whatever) is a beautiful sight..

[RL3AO]

SEPAT (he/she whatever) is a beautiful sight..

Its Malaysian for "A fresh water fish with small climbing perch".

[DESTRUCTION5]

SEPAT (he/she whatever) is a beautiful sight..

Its Malaysian for "A fresh water fish with small climbing perch".

LMAO..NIce

[wxmann_91]

I don't want to jump the gun, but latest visibles indicate that an ERC may be starting, not surprising given the strong instability in that area. At least if it doesn't start now it should start one tonight during the DMAX. Of course, am waiting for an SSMI pass to confirm.

[Chacor]

TY 0708 (SEPAT)
Issued at 06:00 UTC, 15 August 2007
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 0708 SEPAT (0708)
ANALYSIS
PSTN 150600UTC 15.7N 128.1E GOOD
MOVE W 06KT
PRES 935HPA
MXWD 095KT
GUST 135KT
50KT 80NM
30KT 170NM
FORECAST
24HF 160600UTC 17.5N 126.6E 90NM 70%
MOVE NW 06KT
PRES 925HPA
MXWD 100KT
GUST 140KT
48HF 170600UTC 20.4N 124.6E 150NM 70%
MOVE NNW 09KT
PRES 925HPA
MXWD 100KT
GUST 140KT
72HF 180600UTC 23.2N 122.1E 220NM 70%
MOVE NW 09KT
PRES 935HPA
MXWD 095KT
GUST 135KT

[bob rulz]

Unbelievable! And of course it's going completely unnoticed by us Westerners. There'll be a 10-second story about it when it hits Taiwan, then back to a huge, 10-minute report on Dean, which won't even be to the Lesser Antilles by then.

[RattleMan]

24HF 160600UTC 17.5N 126.6E 90NM 70%
MOVE NW 06KT
PRES 925HPA
MXWD 100KT
GUST 140KT

If that 24h forecast holds true, it will become the most intense WPAC storm yet this year. Currently, Man-yi holds that title with 930hPa/95kt.

[Typhoon Hunter]

Wow, I'm speechless. I checked this yesterday and it was pretty tame, now just got back from Beijing and see the updates!

I'm going to start a new thread soon since I will be travelling to Taiwan tomorrow to attempt to intercept this extremely powerful storm.

More updates to follow....

[Chacor]

Wow, I'm speechless. I checked this yesterday and it was pretty tame, now just got back from Beijing and see the updates!

I'm going to start a new thread soon since I will be travelling to Taiwan tomorrow to attempt to intercept this extremely powerful storm.

More updates to follow....

Stay safe Typhoon Hunter!

[Typhoon Hunter]

Thanks Chacor!

Here's the latest sat analysis. Up to T7.0!!

372
TPPN10 PGTW 151215

A. SUPER TYPHOON 09W (SEPAT)

B. 15/1130Z

C. 16.0N/7

D. 127.7E/7

E. ONE/MTSAT

F. T7.0/7.0/D2.0/24HRS STT: D0.5/06HRS (15/1130Z)

G. IR/EIR LLCC

01A/PBO EYE/ANMTN. 16NM WMG EYE SURROUNDED BY WHITE
ADDED 1.0 EYE ADJ YIELDS DT OF 7.0. DBO DT. PT AGREES.
UNREP MET GIVES 6.5. SYSTEM UNDERGOING RAPID
DEVELOPMENT.

DELEO

[HURAKAN]

Nothing less could be expected from the WPAC!!! Typhoon Hunter, stay safe and keep us informed.

[KBBOCA]

That is one mean-looking storm.

Currently forecast to hit Taiwan as a Cat 4. Yikes.

Forecast here:
http://www.wunderground.com/tropical/tr ... ml#a_topad

Current Sat here:
http://www.wunderground.com/tropical/tr ... 9_sat.html

[Chacor]

WDPN31 PGTW 151500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W WARNING NR14//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. SUPER TYPHOON (STY) 09W (SEPAT) COMPLETED A RAPID
INTENSIFICATION CYCLE 12 HOURS AGO. IN THE PERIOD BETWEEN
14/00Z AND 15/00Z, SATELLITE-DERIVED INTENSITY ESTIMATES
INCREASED NEARLY 50 KNOTS. SINCE THEN, THE STORM HAS MAINTAINED
SUPER TYPHOON INTENSITY DESPITE SHORT-TERM CONVECTIVE FLUCTUATIONS
WITHIN THE EYEWALL. THE SYSTEM HAS SLOWED AND TURNED MORE POLEWARD
OVER THE PAST 12 HOURS.
B. THE CURRENT POSITION IS BASED ON A TIGHT GROUPING OF EYE
FIXES FROM PGTW, RJTD, AND KNES. A 150951Z SSMI PASS (85H) DEPICTS
A SOLID EYEWALL AND A VERY SYMMETRIC LOW LEVEL CIRCULATION MEASURING
ABOUT 450 NM ACROSS. SATELLITE-DERIVED INTENSITY ESTIMATES RANGE
FROM 127 KTS TO 140 KTS, AND THIS SUPPORTS AN INITIAL INTENSITY OF
135 KNOTS. OBSERVATIONS OF RECENT ENHANCED IR IMAGERY YIELD A
CLOUD-FREE, 16-NM DIAMETER EYE THAT HAS WARMED SEVERAL DEGREES (C)
SINCE 15/00Z. THE INTENSE SYSTEM IS MAINTAINED BY STRONG EQUATORIAL
OUTFLOW THAT HAS MERGED WITH THE UPPER LEVEL FLOW (FROM NORTHEAST
TO SOUTHWEST) OVER THE SOUTH CHINA SEA. EARLIER UPPER AIR
OBSERVATIONS WELL TO THE SOUTHEAST OF THE STORM (PTRO/PTYA
AT 15/00Z) INDICATED SOUTHEASTERLY FLOW BETWEEN 600 MB AND 400 MB,
WHICH MAY INDICATE THE DEVELOPMENT OF PERIPHERAL ANTICYCLONIC FLOW
AND A SUSTAINED TURN TOWARD THE NORTHWEST (AS DEPICTED IN MOST MODEL
FIELDS).
3. FORECAST REASONING.
A. THERE HAS BEEN A SMALL INCREASE IN FORECAST TRACK SPEED
STARTING AT 24 HOURS, AND THIS HAS COMPRESSED THE TIMELINE FOR AN
INITIAL LANDFALL ON TAIWAN AND A SECOND LANDFALL IN SOUTHEASTERN
CHINA. SINCE THE SYSTEM IS EXPECTED TO BE WELL INLAND BY THE 96-
HOUR POINT, THE 120-HOUR FORECAST POSITION HAS BEEN DROPPED.
B. STY 09W IS BEGINNING ITS TRANSITION TO A POLEWARD TRACK, AS
PERIPHERAL RIDGING COMBINES WITH THE DEEP LAYER (700 MB TO 200 MB)
SUBTROPICAL RIDGING TO THE NORTH (CENTERED OVER JAPAN). AS THIS
OCCURS, THE STEERING PATTERN WILL ORIENT SOUTHEAST TO NORTHWEST,
INITIATING A NORTHWESTWARD TRACK THROUGH 72 HOURS. ALL MODELS
SHOW THIS SCENARIO WITH ONE EXCEPTION: THE EGRR TRACKER IS A WESTERN
OUTLIER AS IT APPEARS TO LOSE THE STORM CIRCULATION AND MERGE THE
STORM WITHIN THE BROAD TROUGHING OVER THE SOUTH CHINA SEA. FAVORABLE
UPPER LEVEL OUTFLOW AND HIGH SEA SURFACE TEMPERATURES SUPPORT SOME
ADDITIONAL SHORT-TERM INTENSIFICATION. HOWEVER, STY 09W SHOULD
WEAKEN SLIGHTLY BEFORE STRIKING TAIWAN DUE TO LAND INTERACTION AND
SOMEWHAT LOWER SEA SURFACE TEMPERATURES/OCEAN HEAT CONTENT.
C. ALL EXTENDED MODELS DEPICT LANDFALL WITHIN 96 HOURS. THE
STORM WILL WEAKEN SUBSTANTIALLY BETWEEN 72 HOURS AND 96 HOURS
AS THE LOW LEVEL CIRCULATION BECOMES DISRUPTED BY TAIWAN AND
THEN MAKES LANDFALL IN SOUTHEASTERN CHINA.
FORECAST TEAM: DELTA//

[Chacor]

Eye has become larger.

[Andrew92]

OMG Typhoon Hunter, be very careful! I admire you a lot for going out into the face of danger like this, but please stay safe! Your life is more important than just an adventure.

Man I hope this thing weakens, AND THEN SOME. I haven't been posting (I usually try to stay quiet but still read informative posts during active times like this), but my initial thoughts were that it would be a slow developer. This storm has knocked me off my feet (no pun intended).

This is terrifying. I will definitely be praying for those in Taiwan and China.

-Andrew92

[wxmann_91]

OK, I was wrong about ERC.

New Navy estimate is 140 kt - making SEPAT the first Cat 5 this WPAC season (by JTWC standards).

A ring of very cold cloud tops (-80°C) completely surrounds the eye. The only thing preventing this from reaching possible T8.0 is the relatively cool eye. Once that eye clears out... oy...

BTW,
down to 925 hPa and 100 kt 10-min per JMA.
That's pretty darn strong.

RSMC TROPICAL CYCLONE ADVISORY
NAME TY 0708 SEPAT (0708)
ANALYSIS
PSTN 151800UTC 16.7N 127.2E GOOD
MOVE NW 09KT
PRES 925HPA
MXWD 100KT
GUST 140KT
50KT 100NM
30KT 190NM
FORECAST
24HF 161800UTC 19.6N 125.0E 90NM 70%
MOVE NW 09KT
PRES 920HPA
MXWD 105KT
GUST 150KT
48HF 171800UTC 22.6N 122.5E 150NM 70%
MOVE NW 10KT
PRES 920HPA
MXWD 105KT
GUST 150KT
72HF 181800UTC 24.7N 120.7E 220NM 70%
MOVE NW 07KT
PRES 945HPA
MXWD 085KT
GUST 120KT

EDIT: just realized the eye has cooled a bit in the latest IR images. Hmmm....

[WindRunner]

Cooled? Should be interesting to watch late into tonight . . . can't wait for vis!

Also interesting to see that both JMA and JTWC strengthen it further . . . sadly, they might be underdoing it a little, as is common with forecasting storms of this intensity . . .