Note about the JTWC forecasts!!!!

[Alyono]

It will NOT happen. There is no way there can be two typhoons as close as they currently are forecast to be in 5 days.

What is more likely to happen is that the two depressions will MERGE into a single typhoon. However, unless the track error is extremely high, there will not be two of them

[Meow]

I guess you have not read the prognostic reasoning from JTWC. It says that 12W and 13W will merge into a single system and intensify into a typhoon.

[Alyono]

I guess you have not read the prognostic reasoning from JTWC. It says that 12W and 13W will merge into a single system and intensify into a typhoon.

then why are the 120 hour positions separate?

http://www.usno.navy.mil/NOOC/nmfc-ph/R ... wp1213.gif
north of Taipei

http://www.usno.navy.mil/NOOC/nmfc-ph/R ... wp1313.gif
east of Taipei

their reasoning does not match their forecast

[wxman57]

Yes, very strange. If you're forecasting two systems to merge in a few days you don't forecast each to be a separate typhoon at day 5. Their TS force wind fields would be mixed together.

[Meow]

then why are the 120 hour positions separate?

http://www.usno.navy.mil/NOOC/nmfc-ph/R ... wp1213.gif
north of Taipei

http://www.usno.navy.mil/NOOC/nmfc-ph/R ... wp1313.gif
east of Taipei

their reasoning does not match their forecast

I don’t care about JTWC. They often do mistakes.

[euro6208]

really interesting development for both systems...

[vrif]

JTWC's merger is only a couple of nautical miles away from each other. Close enough for me to count as a merger.

[Alyono]

there is still a timing mismatch. There is only a 96 hour position for Depression 13W. However, its 96 hour position is not is the same place as is the 96 hour position for Depression 12W

[vrif]

there is still a timing mismatch. There is only a 96 hour position for Depression 13W. However, its 96 hour position is not is the same place as is the 96 hour position for Depression 12W

Good point. Sounds like JTWC is over estimating the strength of at least one of the systems.

['CaneFreak]

This is a really annoying problem with JTWC. I wonder why they can't just keep the two systems separate?

[Alyono]

and now, despite every single dynamical model showing a large typhoon, they go with a TS... Even the GFS raw output has winds near typhoon force

trying to understand the forecast logic

['CaneFreak]

Shoot me a PM if you figure it out because I would REALLY like to know why they backed it down. Forecast rationale seems sloppy.

and now, despite every single dynamical model showing a large typhoon, they go with a TS... Even the GFS raw output has winds near typhoon force

trying to understand the forecast logic

[HURAKAN]

they just issued last advisory on TD 13W .

[Typhoon Hunter]

Yes I was noticed this too and was wondering what the heck was going on, very strange. Regarding intensity all the recent model runs I've seen for 12W suggest it will become a typhoon!

[dexterlabio]

They should've just shown the other system dissipated or absorbed or something like that...first of all, it's quite confusing when you first see a dissipating TD becoming a Cat1 typhoon in less than 6 hours.. also the time and the spot where they expect the weaker system to merge with the other system just don't come together... I recall the same situation with TY Parma and TD 19W in 2009. .

[vrif]

Looking at the latest 00Z GFS run. The runs are showing a broader and broader circulation for Trami. This trend is see-able from the 12Z -> 18Z -> 00Z runs. This could be a reason why the intensity forecast from JTWC and JMA has been lower than expected.

[vrif]

Looks like the models changed again regarding intensity. Now it is picking up Trami to have a good closed circulation