ATL: Ex COLIN - Discussion

[KWT]

Thats amazing the NHC go as high as 32% considering the set-up ahead looks pretty poor, its probably somewhat marginal now...I'd be amazed if it got to that sort of strength.

I wonder whether the LLC will try to catch up with the convection?

[Vortmax1]

I wonder whether the LLC will try to catch up with the convection?

That's probably your sign KWT.

[ozonepete]

This vortex can take only one of two forms, either a 3-Wave or a 5-Wave pattern. Each 'wave' is a lobe on the vortex.

Not quite right. From http://weatherfaqs.org.uk/node/145:

These long-waves are key elements in the atmospheric circulation, and can be traced well into the stratosphere. At any one time, there are between 3 and 7 such waves, the number in any particular latitude band dependent upon a fine balance between the speed of the airflow through the trough/ridge system and the wavelength.

Nice point, supercane. Yes there can be anywhere from 3 to 7 longwaves troughs. Since the number of troughs and their depths must balance out energy-wise, the more troughs you see the less deep they usually are. It would be extremely unusual to see 5 really deep troughs rotating around the northern or southern hemisphere in the westerlies in the summer. And obviously, no matter whether there are as little as 3 or as many as 7, they are rarely of the same depth (rarely extend the same distance down into the subtropics.) The main point to take away here, and the main point they were making in the NHC discussion, is that with the current pattern of 5 longwave troughs rotating around the northern hemisphere, they are not extremely deep or strong and are moving along at a fairly slow clip, as you would expect in the summer season. This implies that the first trough that this storm encounters may not be deep enough to turn it, and then the next one behind it might not turn it until it has gone more west than the UKMET...ECMWF...AND GFDL say. I would agree with the NHC that those models are being too aggressive when progging a mid-latitude trough to dig that deep in the beginning of August.

Also, supercane, that was very nice the way you drew the troughs into the 500mb chart, although I think you drew the lines too deep into the subtropics at the bottom. But I really loved how you illustrated something that a lot of people here were having trouble visualing. Great discussion.

[ConvergenceZone]

Squarethecircle, regarding the intensity probability table you posted, yes, there's always going to be a possibility, you never say never when it comes to the tropics. But he seemed pretty confident that it would go hurricane. That's all I was saying. There's just nothing to support that ...

Now, I still think it has the possibility of making it to a moderate tropical storm IF it gets it's act going quickly. That needs to occur though before the TULL gets a hold of it...

[supercane]

No change in SSD Dvorak classification, supporting continued TD status:

DATE/TIME LAT LON CLASSIFICATION STORM
02/2345 UTC 13.1N 44.3W T2.0/2.0 04L -- Atlantic
02/1745 UTC 12.8N 41.7W T2.0/2.0 04L -- Atlantic

For those interested, 277 deg heading at around 25 knots.

[KWT]

Yeah CZ agreed, the problem this thing has now is there appears to be some sort of easterly shear now which IMO is related to the SAL surge just to the north but who knows. Still had time to make the cut but after 48hrs things do start to go downhill yet further.

[Gladstone]

THE CURRENT 5-WAVE PROGRESSIVE PATTERN
Don't have GARP like wxman57, but will draw trough axes on 500-mb analysis at 12Z.

Nice work supercane; and I'm sure we can all mentally extrapolate now how a 3-wave pattern would result in larger and deeper troughs (sometimes seen in winter.)

[gatorcane]

The CMC may just have it right this time. TD is very weak and nearly a wave. That would mean it stays mostly on a 280 heading or so for the next several days where it starts to accelerate under a ridge that is moving in tandem with it (clearly seen on WV loops). That could put it very near or through the NE Leewards. Had it really been more organized, I think it would be already moving around 290 to 300 or so.

I think we'll see models shift left overtime but the system is likely going to remain weak due to the strong shear.

[cycloneye]

00z Best Track

AL, 04, 2010080300, , BEST, 0, 134N, 441W, 30, 1007, TD

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 010.invest

No upgrade yet.

[CrazyC83]

Center seems to have relocated?

[KWT]

Yeah Gatorcane I agree, though there probably won't be much left if it does get into better conditions near the Bahamas region.

[Gustywind]

No change in SSD Dvorak classification, supporting continued TD status:

DATE/TIME LAT LON CLASSIFICATION STORM
02/2345 UTC 13.1N 44.3W T2.0/2.0 04L -- Atlantic
02/1745 UTC 12.8N 41.7W T2.0/2.0 04L -- Atlantic

For those interested, 277 deg heading at around 25 knots.

So more west for the moment than WNW expected, not good news foe the EC islands even if it's unofficial...

[gatorcane]

Yep, it would be nice to see if the models would actually initialize with a nearly due W movement for a change instead of trying to keep lifting it WNW from the beginning.

I keep looking at the SAT loops and cannot see how it is going to gain much lattitude any longer the next several days with that monster ridge you can see building in from the subtropical Central Atlantic.

[Gustywind]

:uarrow:
Yep, it would be nice to see if the models would actually initialize with a nearly due W movement for a change instead of keep trying to lift it WNW from the beginning.

Absolutely you're 100% right Gatorcane, that could be interresting but hoping that wnw movement begins very quickly. Let's wait and see as usual.

[CrazyC83]

That movement of due west, if it holds up, would keep it below the TUTT and into a favorable environment once in the Caribbean.

[Gladstone]

This vortex can take only one of two forms, either a 3-Wave or a 5-Wave pattern. Each 'wave' is a lobe on the vortex.

Not quite right. From http://weatherfaqs.org.uk/node/145:

These long-waves are key elements in the atmospheric circulation, and can be traced well into the stratosphere. At any one time, there are between 3 and 7 such waves, the number in any particular latitude band dependent upon a fine balance between the speed of the airflow through the trough/ridge system and the wavelength.

Thanks for the good article supercane. I was relying on a very old memory, ha-ha. Most likely, the 3 and 5 wave patterns are the dominant ones - but clearly not the only ones as you've properly educated us.

Portastorm also got a piece of the puzzle by noting the vortex is measured at 500mb.

Here's a bit more on the Polar Vortex:
http://en.wikipedia.org/wiki/Polar_vortex

[Gustywind]

[CrazyC83]

Definitely a small storm, that is for sure. Looks to be a TS though since Dvorak tends to underestimate small storms.

[KWT]

Yeah its certainly not picking up much latitude, still heading pretty much 280 as it has been doing all day, though with the East shear occuring now looks like the convection may even be slightly moving south of west....but thats not occuring for sure.

[redfish1]

i think we will see a shift to the west with the models