ATL: PETER - Remnants - Discussion

[grapealcoholic]

It'll close up as soon as shear lets up. Warm waters, plenty of vorticity

[Nimbus]

https://imagizer.imageshack.com/img923/272/XWaVay.gif

Almost looks like 3 different investments there, one on the Western edge of the screen, and then a north and south blob.

Just the one hot tower sprouting in that saved video, and the large envelope "On the wings of the night".

[tolakram]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

[AlphaToOmega]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

50/50 with such intense model support?
I would keep the 5-day chances at 90%. It would mean a lot for the credibility of the NHC if a wave that wave given a 90% chance of development failed to develop.

[tolakram]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

50/50 with such intense model support?
I would keep the 5-day chances at 90%. It would mean a lot for the credibility of the NHC if a wave that wave given a 90% chance of development failed to develop.

Nah, early predictions have busted a lot, they are just that, predictions. This area is generally where they fail the most and it means nothing to their credibility.

[GCANE]

GFS still has the TUTT anchored over the Virgin Islands.
IMHO, chances are very good that this will decouple around PR with the LL vort continuing in the Carib.
Could see something spin up in the West Carib.

[aspen]

If 95L is going to develop, we will have to see it being much better organized by Friday night or Saturday morning. That’s when the GFS and HWRF have it become a TC. If it’s not a TC by the end of Saturday, the chances for it becoming significant or surviving the TUTT starting midday Monday go down significantly.

[Ubuntwo]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

50/50 with such intense model support?
I would keep the 5-day chances at 90%. It would mean a lot for the credibility of the NHC if a wave that wave given a 90% chance of development failed to develop.

By my count around 32 EPS members and 21 GEFS members develop this. 63% and 68% respectively. So 60 or 70% (depending on how you weigh operational runs) is about right. They are keeping it at 90% mostly for continuity's sake.

Not unusual for a 90% to fail development. After all, how many 10%'s have we seen upset and develop anyways?

[SFLcane]

Meh….

Next.

[al78]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

50/50 with such intense model support?
I would keep the 5-day chances at 90%. It would mean a lot for the credibility of the NHC if a wave that wave given a 90% chance of development failed to develop.

By my count around 32 EPS members and 21 GEFS members develop this. 63% and 68% respectively. So 60 or 70% (depending on how you weigh operational runs) is about right. They are keeping it at 90% mostly for continuity's sake.

Regardless it's not unusual for a 90% to fail development. After all, how many 10%'s have we seen upset and develop anyways?

If the genesis probability forecasts are reliable it should be somewhat unusual for a 90% probability invest to fail to develop, or a 10% probability invest to develop. Any one probabilistic forecast cannot be right or wrong, but the forecast reliability can be tested using many probabilistic forecasts. If the forecasts are reliable, an invest that has a 90% probability of development into a tropical cyclone should, based on historical forecasts, develop approximately nine times out of ten. If a 90% probability invest is only developing half the time based on many prior forecasts, something is not right with the forecast methodology, which could be something like the ensemble distribution is not correctly representing the uncertainty (in this example the ensembles could be under-estimating the uncertainty).

[abajan]

Showers and thunderstorms have become slightly less organized in
association with a tropical wave located a little more than 800
miles west-southwest of the Cabo Verde Islands. However,
environmental conditions are expected to be conducive for
development during the next few days, and a tropical depression is
still likely to form late this week or this weekend. This system
is expected to move westward to west-northwestward across the
tropical Atlantic during the next several days.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.

[Ubuntwo]

If the genesis probability forecasts are reliable it should be somewhat unusual for a 90% probability invest to fail to develop, or a 10% probability invest to develop. Any one probabilistic forecast cannot be right or wrong, but the forecast reliability can be tested using many probabilistic forecasts. If the forecasts are reliable, an invest that has a 90% probability of development into a tropical cyclone should, based on historical forecasts, develop approximately nine times out of ten. If a 90% probability invest is only developing half the time based on many prior forecasts, something is not right with the forecast methodology, which could be something like the ensemble distribution is not correctly representing the uncertainty (in this example the ensembles could be under-estimating the uncertainty).

Every Atlantic 90% has developed over the past two years (dozens of storms), so one could almost say we are 'due' for a 90% to fail Now that I say it, this thing is gonna spin up, isn't it?

[hcane27]

And so the reduction in likelihood of expected development begins.

[aspen]

*pokes with a stick* c’mon, do something

[kevin]

*pokes with a stick* c’mon, do something

[stormchazer]

I think we have become to use to everything forming and it does not always happen. What is also true, and we have seen it many times is there is often this type of drama before formation. “Yes it will! No it won’t” For my part, though having no meteorological skill, I am a bit more concerned if it takes longer to develop as might be less of inclination to move poleward.

Of course if the TUTT kills it, all the better.

[SoupBone]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

With absolutely no data to back this up, I mentioned that this season appeared to start early, so maybe it also closes shop a little earlier as well. With more and more threats in May, are we starting to see the season begin and end dates shift a little?

[ElectricStorm]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

With absolutely no data to back this up, I mentioned that this season appeared to start early, so maybe it also closes shop a little earlier as well. With more and more threats in May, are we starting to see the season begin and end dates shift a little?

Most seasons have been backloaded recently so I don't think activity in May has anything to do with it. But I think the high amount of activity in August might. There's been several years where August has been very active, followed by a less active September. I think the reason for that is the favorable MJO/CCKW all line up in August but the unfavorable phase arrives in September. That being said, some of those years have gone on to have big Octobers when the favorable phase returns and I think that's what we have to watch out for this year IMO.

As for 95L, I think the best chance for development will be after it gets past the TUTT. If there's anything left of it then, it might be able to develop but it's all up in the air right now. Doesn't appear to have a bright future in the next several days though.

[toad strangler]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

With absolutely no data to back this up, I mentioned that this season appeared to start early, so maybe it also closes shop a little earlier as well. With more and more threats in May, are we starting to see the season begin and end dates shift a little?

No way. Last year was epic late

[kevin]

I said 60/90 before, now I think 50/50 is probably the best this deserves. CV might have shut down already, which is not that unusual, but it means we have to wait until these waves get well west before we know if anything develops. I'll say this and it will spin up within 24 hours.

With absolutely no data to back this up, I mentioned that this season appeared to start early, so maybe it also closes shop a little earlier as well. With more and more threats in May, are we starting to see the season begin and end dates shift a little?

On the other hand 2020 also started early and had perhaps the most impressive late season (in recent times) with 5 MHs. Also I did some analysis on how 'backloaded' every season was since 2000 and that indicates a slightly upwards trend as you can see in the image below, even though that was mainly caused by 2020. If you remove 2020 you get basically a flat horizontal line which indicates no significant change to late-season development in the last 20 years. I wrote a longer post about it here including an explanation on how I calculated those scores: http://www.storm2k.org/phpbb2/viewtopic.php?f=31&t=121675&p=2926222&hilit=backload#p2926222.