ATL: Ex COLIN - Discussion

[dizzyfish]

First, thank you all for all of your input especially the discussions and explanations regarding the set up that will steer these systems.

Second, (and you won't believe this, or maybe you will ) on my drive home from work at around 3:30 today the guy on the radio said something like "we have Colin out there now and will tell you all about it in a few minutes". I thought - dang what did I miss since 2pm! I really wish they wouldn't say stuff like that. It irritates.

[ROCK]

It does not look too bad, but given it was at 30kts earilier today I don't think it looks any better since then, certainly not to upgrade anyway.

I disagree.. .cloud tops have warmed....no more of the cold tops from yesterday....its sitting over some very warm water over slight shear....LLC not fully tapping into the surface, IMO....still weak...

Convection blowing up quite nicely right now over the center FWIW...

Still racing towards the dry air, going to be most interesting to see if TD4 can keep itself going in what looks like an increasingly poor set-up aloft.

what a difference 30 minutes makes..... but still weak IMO....give me -80 tops and I will put the other foot on board...

[KWT]

Certainly an interesting idea Brutona, I'm still not too sure about how this set-up will evolve, its a toughie for sure!

Now I've got another thing I'm going to throw out there...you know there is a SAL outbreak to the north, that is usually coming with strong easterly winds, I've gotta wonder whether that will force TD4 to keep on a slightly more westerly path then is expected...

At least the system is developing some new deep convection, it was starting to look a touch ragged.

[StormClouds63]

What effect, if any, is the large wave east/southeast of TD-4 having on its development?

[cycloneye]

Very interesting part of discussion:

THE GFS-BASED SHIPS
INTENSITY MODEL IS FORECASTING THE SHEAR TO INCREASE TO MORE THAN
30 KT...WHICH WOULD NORMALLY RESULT IN WEAKENING OF A TROPICAL
CYCLONE. HOWEVER...THESE HIGH SHEAR VALUES MAY BE AN ARTIFACT OF
THE THE GFS HAVING MUCH STRONGER UPPER-LEVEL WINDS AS COMPARED TO
THE OTHER GLOBAL MODELS...AND ALSO DUE TO 500 KM RADIUS THAT THE
SHIPS USES IN COMPUTING SHEAR VALUES. IF THE DEPRESSION REMAINS
UNDERNEATH THE UPPER-LEVEL ANTICYCLONE RATHER THAN OUTRUNNING IT
...THEN THE CYCLONE WILL END UP STRONGER THAN THE OFFICIAL FORECAST
INDICATES.

[Ivanhater]

Wow..very interesting snippet from the latest NHC DISCO

GIVEN THE CURRENT 5-WAVE PROGRESSIVE
PATTERN...MY FEELING IS THAT SUCH SIGNIFICANT EROSION OF THE
SUBTROPICAL RIDGE WOULD BE SOMEWHAT OVERDONE FOR THIS TIME OF THE
YEAR. AS A RESULT...THE OFFICIAL FORECAST TRACK IS A LITTLE TO THE
LEFT OF AND SLOWER THAN THE PREVIOUS ADVISORY...AND IS SIMILAR TO
THE CONSENSUS MODELS...TVCN AND TVCC...ESPECIALLY AT DAYS 4 AND 5.

[cycloneye]

Slightly left shift.

[KWT]

A very interesting discussion make no mistake.

I remember someone else mention that the SHIPS maybe overdoing the shear levels due to the set-up, interesting to see the NHC make the same point!

[ColinDelia]

What is a "5-WAVE PROGRESSIVE PATTERN"?

[hurricaneCW]

That was an interesting discussion on both the track and the intensity, which by the way went up a little. Still, even if the shear were 20-25 knots instead of 30+ knots, it would still likely get destroyed given its tiny structure; however, it still has almost 2 days to ramp up in a relatively favorable environment. I'm watching to see if it'll have a strong convective burst like it did the past few days during the evenings. Convective bursts would help eliminate any mid-level dry air and possible increase the moisture axis around it.

[KWT]

Wow..very interesting snippet from the latest NHC DISCO


MY FEELING IS THAT SUCH SIGNIFICANT EROSION OF THE
SUBTROPICAL RIDGE WOULD BE SOMEWHAT OVERDONE FOR THIS TIME OF THE
YEAR. AS A RESULT...THE OFFICIAL FORECAST TRACK IS A LITTLE TO THE
LEFT OF AND SLOWER THAN THE PREVIOUS ADVISORY...AND IS SIMILAR TO
THE CONSENSUS MODELS...TVCN AND TVCC...ESPECIALLY AT DAYS 4 AND 5.

I think thats something most of us on here have been talking about, the upper ridge perhaps not weakening quite as quickly as some of the models are currently suggesting. I'm keeping a close eye on the Upper High and that SAL surge, typically the mid level easterlies you get with such a feature is pretty tough to break from.

[tolakram]

So nice to have Stewart this year, his discussions are second to none in detail and reasoning.

[cycloneye]

Nice little ball.

[KWT]

Yep back to the ball look again that it had this morning when it was upgraded...though note the center is probably on the eastern edge of that ball, will probably try and work its way back under the convection which will mean perhaps a small relocation if the convection holds westwards.

[Dean4Storms]

What is a "5-WAVE PROGRESSIVE PATTERN"?

I'm scratching my head on that one too. Is he talking about the jet stream configuration across the CONUS?

[tolakram]

I'm going to guess something to do with tracking global 'waves'.

http://www.wxonline.info/topics/waves.html

[Gustywind]

Given the latest weather forecast, our pro mets of Meteo-France are a bit pessimistic anticipating a TD4 in vicinity of Guadeloupe Wednesday night Hope that this trend will end quickly. Let's wait and see if this trend is confirmed during the next 24-48H.

[Nimbus]

IF THE DEPRESSION REMAINS
UNDERNEATH THE UPPER-LEVEL ANTICYCLONE RATHER THAN OUTRUNNING IT
...THEN THE CYCLONE WILL END UP STRONGER THAN THE OFFICIAL FORECAST
INDICATES.

Moving WNW at a good clip but we can watch the high wispy cirrus clouds out in front of the storm to see if he is running out from under the anticyclone.

[Dean4Storms]

I just don't buy the east out to sea models on this one either. I also think once the trough lifts out the ridge turns Colin by then back more westward so anywhere from Central Florida up to SC is my hunch.

[Portastorm]

The five-wave progressive pattern deals with the 500mb flow across a very large area of the globe (i.e. at least 180 degrees of longitude) over a short period of time.