TD #4 East Atlantic,Comments,Sat Pics,Models Thread #2

[SouthFloridawx]

Yes be careful with those models as it was initiated more of a north of west initialization.

[Josephine96]

Still a VERY LONG way off.. It'll be a long 1 1/2-2 weeks if this thing decides it wants to make it all the way across

[Evil Jeremy]

where are those the new models?

[Scorpion]

If this were in the Gulf or Caribbean I think it would be a 40 kt TS right now.

[ronjon]

I see no evidence TD #4 will turn to the NW anytime soon after my investigations - can somebody explain why using sat pics or other visuals as backup? Based on some water vapor loops, one is below, the subtropical ridge above TD #4 is not retreating to the east at all. The flow is pretty solid from East to West where TD #4 is right now....

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

The ULL near 22-42 is supposed to create a weakness in the ridge. There is still some doubt as to if this will happen. A PRO MET on another site indicates the possibility of a more W or W-NW track.

From Clark at FLHurricane.com:

Models suggest that anything that develops out there should head to the west-northwest to northwest, recurving well out at sea. I'm not sure how much stock to put into that one, as they've been overdoing such tracks so far this year and there is no indication of a weakness for anything to move into at this time. The satellite & model derived steering flow products from UWisconsin (http://cimss.ssec.wisc.edu/tropic/real- ... s-dlm.html) suggest a more westerly to west-northwesterly motion based solely off of upper-level steering patterns. The GFS, which many of the steering-pattern models such as the BAM series are derived from, shows the development of an upper-level low out ahead of this disturbance, likely interacting with it and forcing it on a more northwesterly pattern. This shows up well in the 500hPa vorticity fields from today's 06z run (http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... =Animation) and has been a pretty persistent feature in the model looking back through the past few runs. Other models don't depict the disturbance and its environment well from the outset or show a similar evolution to the GFS.

....Track will ultimately depend on whether or not that cut-off upper low ahead of it actually does develop and forces the disturbance on a more northwesterly track. Otherwise, it's likely to ride more westward (or west-northwestward) under the building ridge.

[cycloneye]

[Sanibel]

Ooo, big gulp of dry air there. Practically melted the top half.

[wxmann_91]

I personally would disregard models attm and focus on TRENDS.

This may recurve in the long run but the GFS idea of it going directly northwest, IMO, is incorrect.

[wxman57]

I see no evidence TD #4 will turn to the NW anytime soon after my investigations - can somebody explain why using sat pics or other visuals as backup? Based on some water vapor loops, one is below, the subtropical ridge above TD #4 is not retreating to the east at all. The flow is pretty solid from East to West where TD #4 is right now....

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

Perhaps I can assist. There does appear to be a tremendous amount of model consensus in a track out to sea. The reason for that is almost all models see the ridge to the north breaking down in 36-48 hours as a trof moves farther off the east U.S. Coast. Take a look at the mean mid-level flow charts for 18Z today, Wednesday, and Friday:

18Z today
http://myweb.cableone.net/nolasue/debby6.gif

18Z Wednesday
http://myweb.cableone.net/nolasue/debby7.gif

18Z Friday
http://myweb.cableone.net/nolasue/debby8.gif

The stronger that Debby gets, the more likely that it turns northwest and heads out to sea. The weaker the storm (or if it dissipates), the more westerly it will track. So the bottom line is that the highest probability is that it will follow model guidance and head to the NW wher it will move over cooler and cooler water and eventually dissipate. If it dissipates in the next day or two, then the remnant wave will move westerly. But it won't remember it was TD 4 or Debby, so it won't have any better chance of redevelopment than the two waves ahead of it that are struggling.

Just checked a long (24hr) wv loop of the Atlantic. Can see a trof digging southeastward near 25N/50W ahead of TD 4. That's an indication that the GFS may be correct (along with most other models). There really is nothing to suggest it'll go anywhere near the Caribbean or the east U.S. Coast at this time.

[wxmann_91]

The reason is they are all initialized from the GFS. But if the GFS is wrong, then wouldn't the general consensus follow suit?

GFS and ECMWF differ from each other quite drastically. In fact, the 12Z run of the Euro keeps Debby aoa 20 degrees latitude, or so I've heard elsewhere.

12Z GFS already had a UL developing to the northwest of TD 4. But I don't see it anywhere.

[gatorcane]

I see no evidence TD #4 will turn to the NW anytime soon after my investigations - can somebody explain why using sat pics or other visuals as backup? Based on some water vapor loops, one is below, the subtropical ridge above TD #4 is not retreating to the east at all. The flow is pretty solid from East to West where TD #4 is right now....

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

Perhaps I can assist. There does appear to be a tremendous amount of model consensus in a track out to sea. The reason for that is almost all models see the ridge to the north breaking down in 36-48 hours as a trof moves farther off the east U.S. Coast. Take a look at the mean mid-level flow charts for 18Z today, Wednesday, and Friday:

18Z today
http://myweb.cableone.net/nolasue/debby6.gif

18Z Wednesday
http://myweb.cableone.net/nolasue/debby7.gif

18Z Friday
http://myweb.cableone.net/nolasue/debby8.gif

The stronger that Debby gets, the more likely that it turns northwest and heads out to sea. The weaker the storm (or if it dissipates), the more westerly it will track. So the bottom line is that the highest probability is that it will follow model guidance and head to the NW wher it will move over cooler and cooler water and eventually dissipate. If it dissipates in the next day or two, then the remnant wave will move westerly. But it won't remember it was TD 4 or Debby, so it won't have any better chance of redevelopment than the two waves ahead of it that are struggling.

Just checked a long (24hr) wv loop of the Atlantic. Can see a trof digging southeastward near 25N/50W ahead of TD 4. That's an indication that the GFS may be correct (along with most other models). There really is nothing to suggest it'll go anywhere near the Caribbean or the east U.S. Coast at this time.

Thanks for the explanation. I see the short wave troughs over the Great Lakes and off the East Coast of the US that are pushing ESE but I'm not sure that they will be strong enough and close enough to erode the High so much as anticipated -

plus I think we'll start seeing some weakening of TD #4 because of the lingering African Dust and cooler SSTs as it moves farther away from the warmer and more moist African Coast - so we'll see something, even if its remnants moving west or west-northwest.

[gatorcane]

The Saharan Air layer is still quite strong and it should start to feel its effects over the next 24 hours:

[Scorpion]

The SST's do not get cooler unless the storm is heading towards the NW, which it is not now. SST's can support a Cat 4.

[wxman57]

The reason is they are all initialized from the GFS. But if the GFS is wrong, then wouldn't the general consensus follow suit?

GFS and ECMWF differ from each other quite drastically. In fact, the 12Z run of the Euro keeps Debby aoa 20 degrees latitude, or so I've heard elsewhere.

12Z GFS already had a UL developing to the northwest of TD 4. But I don't see it anywhere.

It really doesn't matter exactly where the GFS initialized the center, as the flow its predicting would take anyting in that general region NW. I get the ECMWF at work. Just logged in and ran the 10-day ECMWF in GARP. It doesn't even see the system, and I analyzed at 1mb increments. It does, however, show the ridge that's north of it now sliding eastward to EAST of the Azores in 3-4 days with a trof across the central Atlantic. So it's showing the same breakdown in the ridge as the GFS, it just doesn't see the storm.

[JTD]

In the opinion of those knowledgable around here,

what is the organizational state of TD #4 at this time. Is it steady-state, weakening, or intensifying?

[wxman57]

In the opinion of those knowledgable around here,

what is the organizational state of TD #4 at this time. Is it steady-state, weakening, or intensifying?

Convection may have diminished a tad over the last 3 hours. Don't see much change in its appearance, though.

[gatorcane]

The SAL is already starting to work its magic. Check out the latest image. It has nearly completely eroded the northern side of TD #4, as expected. Notice the south side is firing nicely but the SSTs are slightly warmer and there is no dust to worry about....this thing should be heading West for a while at the rate it is going.

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/EATL/IR4/20.jpg

[Scorpion]

You're using an old Sat pic.

[wxman57]

Oh, almost forgot. I went to the Coastal Services web site and made some climo maps representing a couple of possibilities. I searched for all storms passing within 200nm of the 120-hr NHC forecast point and got this:

http://myweb.cableone.net/nolasue/climo.gif

1 storm early last century passed near that point and reached Florida. All others over 150+ years headed out to sea.

Then I put in a latitude 2 degrees south of the NHC position and got this:

http://myweb.cableone.net/nolasue/climo2.gif

In this case, all storms headed out to sea that passed within 200nm of 24.5N/46.5W.

So at least Climo says fish, too.

[the_winds_that_sheared_me]

Any chance the storm could start to recurve for a while and then turn back west when the ridge inevitably builds back in?

Kinda like this storm in 2003 http://weather.unisys.com/hurricane/atl ... /track.gif

Or this one from 2004
http://weather.unisys.com/hurricane/atl ... /track.gif

Or this one from 1999
http://weather.unisys.com/hurricane/atl ... /track.gif

Or even this one from 1992
http://weather.unisys.com/hurricane/atl ... /track.gif

Or the ultimate though it recurved close to home and looped
http://weather.unisys.com/hurricane/atl ... /track.gif