ATL: TROPICAL STORM BILL (03L)

[Hurricaneman]

does anybody think that the models are all thrown off on 90l because of td2

[Ivanhater]

[HouTXmetro]

does anybody think that the models are all thrown off on 90l because of td2

I doubt it. IMO TD2 will pave the way for 90L to recurve by exploiting a weakness in the High.

[Hurricaneman]

does anybody think that the models are all thrown off on 90l because of td2

I doubt it. IMO TD2 will pave the way for 90L to recurve by exploiting a weakness in the High.

that would mean the gfs is wrong and after looking at all the features the gfs is wrong and the euro is probably closer to what will happen

[bob rulz]

Very impressive how much it's improved in the last few hours. Definitely a tropical depression at 5am.

Now the question is - which storm will become Ana first? I still think it will be TD2 but 90L got its act together a lot quicker than I expected.

[KWT]

Very interesting to see the GFDL heading more north, indeed the models have trended a little north on the 0z run towards last nights 0z ECM.

Still have to question it IMO as Derek has said.

[KWT]

Looking good, no doubt IMO that this is TD3 now, models have shifted north overnight but as Derek said I'm pretty sure thats a bit of an odd move.

[Wx_Warrior]

0z EURO recurves big time out to sea....EURO must just be getting warmed up!?!

[paintplaye]

http://www.ecmwf.int/products/forecasts/d/animate/catalog/products/forecasts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!72!North%20America!pop!od!oper!public_plots!2009081500!!!step/

Wow Euro is even farther north and to the east!

[KWT]

Its very interesting but I think whats interesting is the models are soooo slow with this systems forward speed, only GFS seems to be close really to be honest.

Anyway every models has shifted northwards towards the ECM it seems.

The models have got a stronger weakness now as well however we shall see what happens, I've seen utterly time and time and time again the models underdo ridging. Frances, Ivan, Dean, Ike to name just a few...

[Wx_Warrior]

Im a big EURO junkie/flukie (ask ROCK)....but EURO must be getting warmed up....? Or gonna make the others look stupid.

[KWT]

Well look how slow it is wxwarrior...

It has this storm at 43W at 72hrs...so that means its only going to move about 12 degree in 72hrs and given this is already moving at 15kts roughly it seems like the ECM is wayyyy to slow.

I've noticed the more NE runs tend to be the slower runs, the 12z ECM was closer to the truth and that shifted SW, but the 0z run is somehow even slower again.

[paintplaye]

Im a big EURO junkie/flukie (ask ROCK)....but EURO must be getting warmed up....? Or gonna make the others look stupid.

Yea well some model is going to do terrible with this storm. It is going to either be the euro that will be way off or the rest of the models.

[wxmann_91]

one other thing, GFS is probably too slow initially. This could be closer to 43-44W not the ~41 the GFS has it at in 48 hours

And that is why the ECMWF recurves as is slow.

No, nothing to do with being slow or fast. ECM is not that much slower than GFS, and the little slower motion the former does show is due to the same reason that it shows recurvature - a stronger weakness that slows the system down. Someone needs to fly a Gulfstream jet out there to get some synoptic data, sad to see such different depictions of the Azores-Bermuda 500mb ridge just 72 hr out (first image GFS, second image ECM)...

[KWT]

Well regardless all the models are going to be too slow, given its moving at 15kts its going to have to slow down pretty soon if its going to not make it to past 43W by 72hrs, probably slow down to about 11kts which whilst possible doesn't seem that likely given a strengthening ridge is aloft at least for now.

I suspect by 72hrs this will be knocking on the door of 50W I reckon...

[Thunder44]

The 0z/15 Ukmet. Maybe a little further north by the end here. But still moves across the NE Leeward islands:

http://www.meteo.psu.edu/~gadomski/UKHE ... kloop.html

[KWT]

Yeah a little further north but not much.

By the way interestingly from all my studying of the models here in the UK, the UKMO tends to handle the subtropical high ridges probably the best out of all the models, its no where near as good with low systems for some reason but Id put even more confidence in it then the UKMO when it comes to upper high strength.

[wxmann_91]

One more thought - the 0Z GFS has trended more towards the ECM, for sures. Keeps a ctrl ATL ULL amplified a little longer like the ECM. 7 times out of 10 models will underdo the strength of a ridge, but those 3/10 times it doesn't, it's usually because models weaken and/or lift out a UL too early, and the UL carves out a stronger weakness than anticipated (remember Ernesto?). Some food for thought.

Additionally, remember the symbiotic relationship TC outflow and ULL's share: they invigorate each other. If TD2/Ana does start dancing with the ctrl ATL ULL, the latter will certainly stay longer than models indicate.

Now, I'm still not favoring one solution over another, but it's just something to keep in the back of the head.

[KWT]

Its a hard call, no doubt the models have adjusted northwards but some models are without a doubt too slow with the forward motion which would surely have a big impact if that were the case...

[cheezyWXguy]

one other thing, GFS is probably too slow initially. This could be closer to 43-44W not the ~41 the GFS has it at in 48 hours

And that is why the ECMWF recurves as is slow.

No, nothing to do with being slow or fast. ECM is not that much slower than GFS, and the little slower motion the former does show is due to the same reason that it shows recurvature - a stronger weakness that slows the system down. Someone needs to fly a Gulfstream jet out there to get some synoptic data, sad to see such different depictions of the Azores-Bermuda 500mb ridge just 72 hr out (first image GFS, second image ECM)...

well sure it has to do with speed. Lets say a weakness is forecast to develop in a certain area in 2 days to the NW of the storm currently. A quick-moving storm is more likely to pass the weakness before it becomes strong enough to lift the storm northward, whereas, if it were to move more slowly, it would allow more time for the weakness to grow, gaining more influence over the storm, thus turning it more northward. In addition, strength is also a factor. As mentioned earlier, the stronger it gets the further west it will go in this case. Assuming it continues to develop the way it is now, and based on current speed/heading, a westward track still seems most likely.

I dont know if this is true or not, but the models may be initializing td2/ana wrong, not recognizing the fact that it has regenerated, and seeing it more as a developing weakness in the ridge. Hypothetically, if there were a weakness so close to 90L at this time, steering would probably be light and a northerly influence would begin to affect the storm. However, this is not the case and 90L is moving at a brisk pace to the west, something that the models don't currently understand. Could this be the source of the error? (sorry if my wording is iffy at parts)