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West Pacific Tropical Action 2011


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I'm just going to keep talking to myself. This is one of the best MW images you'll ever see.

20110526.1157.f18.x.91h_1deg.04WSONGDA.140kts-918mb-162N-1251E.75pc.jpg

Yep... once the eye started clearing out again, it just went to town as expected. Gorgeous presentation. I wouldn't putt any additional intensification out of the picture yet, as the eye really hasn't cleared out all the way. Certainly could get to 145 knots in the next 12 hours before it starts the downward spiral.

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Been tracking this for a week now due to the threat in the Philippines for some ag. business we have there. Very happy it's not making landfall on Luzon...especially as a strengthening Super Typhoon.

It's been imprssive to see how this thing blew up over the past few days.

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5 STY's formed in May in the past 20 years (including Songda): Damrey, Walt, Nida, and Hagibis... all of them formed before Songda i believe...:)

A STY is defined as winds of >100kts I think though. Specifically category 5 (>136kts), I can only find Lola that reached that status before Songda

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5 STY's formed in May in the past 20 years (including Songda): Damrey, Walt, Nida, and Hagibis... all of them formed before Songda i believe...:)

None of them were the equivalent to a SS Cat 5, according to JMA... Cat 3 all of them, except for Walt which was an equivalent to a low end 4. Lola was the only one before June in the W Pac...for the N Hemisphere there were two cat 5s in the Indian Ocean in late Apr and early May 1991 and 1990 respectively.

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A STY is defined as winds of >100kts I think though. Specifically category 5 (>136kts), I can only find Lola that reached that status before Songda

None of them were the equivalent to a SS Cat 5, according to JMA... Cat 3 all of them, except for Walt which was an equivalent to a low end 4. Lola was the only one before June in the W Pac...for the N Hemisphere there were two cat 5s in the Indian Ocean in late Apr and early May 1991 and 1990 respectively.

JTWC and HKO are the only ones that use the Super Typhoon category IIRC... JMA doesn't and JMA is also using 10-min wind averages so it's normal for their wind reports to be lower, SS uses 1-min...

you can see JTWC's best track data here:

http://www.usno.navy...ks/wpindex.html

unless i'm missing something here...:)

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JTWC and HKO are the only ones that use the Super Typhoon category IIRC... JMA doesn't and JMA is also using 10-min wind averages so it's normal for their wind reports to be lower, SS uses 1-min...

you can see JTWC's best track data here:

http://www.usno.navy...ks/wpindex.html

unless i'm missing something here...:)

I convert 10-min to 1-min (inverse of 0.88 factor or 1.1366)... I use JMA because is the official RSMC for the W Pac. That being said, I'm not a fan of the JMA, but neither from JTWC...they are both lacking... NHC is first and BOM second, IMO

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When I have the chance I will dig through the JTWC ATCRs. But I do know that STY Pamela became a Super earlier than Songda in 1976 though not a 5 based upon recon. It subsequently passed over Guam as a 125 kt Cat 4 storm.

Steve

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please do!

anyway i have a question, why is there a discrepancy between JMA and JTWC's winds??? even if i convert JMA's using the 1.13 factor it still comes out to sometimes as much as 30-40kph off... like last year when Megi formed we had recon and JTWC put it at 285kph while JMA is 220kph...:pepsi:

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please do!

anyway i have a question, why is there a discrepancy between JMA and JTWC's winds??? even if i convert JMA's using the 1.13 factor it still comes out to sometimes as much as 30-40kph off... like last year when Megi formed we had recon and JTWC put it at 285kph while JMA is 220kph...:pepsi:

This simply illustrates how subjective satellite intensity estimates are. Different warning centers use different techniques, which yield different results. There is unfortunately no substitute for hard recon data.

And then of course there is the whole topic of converting between 10-min and 1-min winds. There's even debate around it, with folks using anywhere from 1.12 to 1.15 as a conversion factor (to go from 10-min to 1-min). I use 1.1366, the same factor that Jorge (wxmx) uses (see above). He and I were collaborating on some research and just decided to use the same factor so as to avoid confusion. I was previously using 1.15, as per Australia's BoM, but I think that might be generous.

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That being said, I'm not a fan of the JMA, but neither from JTWC...they are both lacking... NHC is first and BOM second, IMO

Agreed. You're not going to get a more thorough analysis of a tropical cyclone (either operationally or in postanalysis) than what the NHC puts out-- not to mention the added benefit of abundant recon data. We are so fortunate.

I also agree that the BoM does a fine job-- especially given that they have a lot less to work with (no recon, less radar/satellite data, etc.). One thing about the BoM, though-- I wish their post-cyclone reports were more detailed. They're really quite brief, and sometimes don't have official landfall intensity estimates.

Sorry to go OT...

Back to Songda... Is it going to miss Japan? The JTWC thinks so. Adam?

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Back to Songda... Is it going to miss Japan? The JTWC thinks so. Adam?

No, I'm bringing it onshore around 6z Sunday as a Cat 1. I have landfall to the northwest of Kagoshima, so exposed areas there very well could see hurricane force winds. My forecast is basically a blend of the GFS/ECMWF tracks. The reasons for this are twofold: 1. given what we know about the global models in their current state, the GFS/ECM are the two best at forecasting cyclone tracks, and 2. look at the current upper level wind field - it's much more meridional than you'd expect for a quick recurving track.

P.S. Agree with Jorge and Josh, 1. NHC, 2. BoM, then everyone else is far below them.

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From the JTWC Prognostic Reasoning:

NUMERICAL MODEL

GUIDANCE IS TIGHTLY PACKED INITIALLY AND BEGINS TO SPREAD AFTER TAU

36, JUST PAST OKINAWA, JAPAN. GFDN AND WBAR TRACK THE SYSTEM TOO FAR

NORTHWARD INTO THE MID-LATITUDE FLOW, THEREFORE THIS FORECAST IS

MORE ALONG WITH GFS AND NOGAPS, BUT JUST SOUTH OF MODEL CONSENSUS.

ADDITIONALLY, THE ECMWF MODEL IS CLOSE TO THE MODEL CONSENSUS AND

PASSES JUST ALONG THE COAST OF SOUTHERN KYUSHU. HOWEVER, THE MODELS

SHOW SOME DIFFERENCES IN FORWARD TRANSLATION SPEED. NOGAPS AND WBAR

ARE THE FASTER MODELS. THIS FORECAST IS TO THE RIGHT OF CONSENSUS

AND SIGNIFICANTLY FASTER IN THE LATER TAUS TO ACCOUNT FOR KNOWN

MODEL ERRORS ASSOCIATED WITH RECURVATURE SCENARIOS.

Are the model biases different in the WPAC? In the Atlantic, models are too quick when recurving storms, hence the north and east bias that NHC and the models have. I still haven't changed my thoughts re: landfall in Kyushu.

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From the JTWC Prognostic Reasoning:

Are the model biases different in the WPAC? In the Atlantic, models are too quick when recurving storms, hence the north and east bias that NHC and the models have. I still haven't changed my thoughts re: landfall in Kyushu.

Could time of the year be a factor to take into account? It's still pretty early in the year for the N Hemi and westerlies are still pretty far south on the mean. Obviously there's the current synoptic setup that you have to analyze, but I could see lower latitude westerlies than modeled. Being that said, I have little experience with forecasting in the W Pac.

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