Disturbed weather in Eastern Atlantic (Is invest 95L)

[cycloneye]

KWT, Bertha in 2008 as a big fish got to 222 pages so there is interest on these type of systems. Lets see how many pages it gets as soon the invest is up.

viewtopic.php?f=68&t=101591&start=0

[Ivanhater]

Fish Likely, but we will also likely see a beautiful Hurricane out of this. Can't forecast a Cat 5, but this one has that possibility.

[KWT]

Yep another big recurving hurricane on this run, probably a major I'd imagine that gets to something like 53-55W and recurves from 30N.

I think thats too far east actually and think they are a little too agressive with the upper troughing, I still think something between 60-65W is the most likely place...

Cycloneye 222 pages for a CV system that became a major hurricane and lasted for 2 weeks...Bonnie lasted for about a day as a TS and nearly got as much!

[cycloneye]

Yep another big recurving hurricane on this run, probably a major I'd imagine that gets to something like 53-55W and recurves from 30N.

I think thats too far east actually and think they are a little too agressive with the upper troughing, I still think something between 60-65W is the most likely place...

But at 64W is Bermuda.

[KWT]

Yeah and thats why I'm not calling this a fish just yet because its still too early to be certain it doesn't threaten Bermuda and Newfoundland, even though the models are actually trending eastwards...

[SoupBone]

Yep another big recurving hurricane on this run, probably a major I'd imagine that gets to something like 53-55W and recurves from 30N.

I think thats too far east actually and think they are a little too agressive with the upper troughing, I still think something between 60-65W is the most likely place...

But at 64W is Bermuda.

An island with 64,000 residents too. I sure hope the models continue to bring the curve more Eastward.

[hurricaneCW]

I'll say this recurves at 55W, but I also think something like 1989's Gabrielle is probably a good match.

http://upload.wikimedia.org/wikipedia/c ... _track.png

[KWT]

If the models are right HCW at the moment then yeah that may not be a bad comprasion system actually, a nice big major hurricane that stays out to sea.

[Aric Dunn]

I will say this again... first off we have no Tropical Cyclone yet and that in itself is a problem for every model. too many times I have seen this happen ( actually every year) long range models develop something and go back and forth from fish to landfall somewhere back to fish over as many days as it takes for the TC to make it the forecast weakness (hence the flag flapping in the wind analogy). It was just two days ago that the GFS had it making landfall in florida and a day before that had a Fish and now its back to a fish (you beginning to see the pattern). it is pure speculation at this point especially since it has not formed yet and better yet the possible formation location is nearly 500 miles long anywhere from the african coast to WSW of the cape verde islands in a time frame of 1 to 5 days ! (depending on you model of choice). I will now rattle of a short list of storms that were supposed to be fishes and ended up not... Floyd, Isabelle, jeanne, frances, IKE, even Dean and Felix and couple runs out to sea before they formed .... I could easily keep going and could make a nice list of storms that were supposed to threaten land but ended up being fishes. The models are exciting I agree but the focus at the moment should be on what its doing now because its still not a TC and until it is the models are ( no pun intended ) fishing in the dark on the eventual track. beyond 3 days at most is all the models are really good for when there is a fully developed TC even with a consensus and the 3 days in this case is simply its westerly motion while its developing. Beyond that pure is speculation.

I apologize for the rambling ...lol

[ronjon]

Here's one paper on the NAO Index/recurvature debate.
http://ams.confex.com/ams/pdfpapers/37310.pdf

For the 10 highest NAO index years the average longitude of re-curvature was 83.4
For the 10 lowest NAO index years the average longitude of re-curvature was 61.8

The data included only storms that reached hurricane strength and formed South of 23.5N and East of 65W

Not saying it's definitive but a good first read for me anyway

Thanks very much for the paper. After a quick read, though, the authors really didn't find a statistical relationship between early and late recurving storms except for Florida where a positive NAO produced more major hurricane FL strikes than a negative. Note: LOR = furthest western longitude of recurvature.

All Hurricanes

NAO Index LOR Index
High NAO Yrs. 1.44 71.2
Low NAO Yrs. -1.32 70.9

[KWT]

Aric true but the troughing is strong, even if the models reduced it it really woulsdn't make a huge amount of difference to the track.

Also this is such a progressive pattern aloft to get to the US it'd probably have to bypass 2-3 troughs and even if it did manage to sneak past the 1st without recurving, the 2nd will almost certainly pick it up.

Its one of the few times I feel VERY confident about the track recurving, normally I'd be very cautious but there is a huge amount of room for error here...If the weakness was strong enough to lift out a sheared very weak closed circulation such as 93L...there is no chance it misses a full blown hurricane.

[ColinDelia]

Here's one paper on the NAO Index/recurvature debate.
http://ams.confex.com/ams/pdfpapers/37310.pdf

For the 10 highest NAO index years the average longitude of re-curvature was 83.4
For the 10 lowest NAO index years the average longitude of re-curvature was 61.8

The data included only storms that reached hurricane strength and formed South of 23.5N and East of 65W

Not saying it's definitive but a good first read for me anyway

Thanks very much for the paper. After a quick read, though, the authors really didn't find a statistical relationship between early and late recurving storms except for Florida where a positive NAO produced more major hurricane FL strikes than a negative. Note: LOR = furthest western longitude of recurvature.

All Hurricanes

NAO Index LOR Index
High NAO Yrs. 1.44 71.2
Low NAO Yrs. -1.32 70.9

Ronjon, you're right. I read that first table wrong.

[Aric Dunn]

Aric true but the troughing is strong, even if the models reduced it it really woulsdn't make a huge amount of difference to the track.

Also this is such a progressive pattern aloft to get to the US it'd probably have to bypass 2-3 troughs and even if it did manage to sneak past the 1st without recurving, the 2nd will almost certainly pick it up.

Its one of the few times I feel VERY confident about the track recurving, normally I'd be very cautious but there is a huge amount of room for error here...If the weakness was strong enough to lift out a sheared very weak closed circulation such as 93L...there is no chance it misses a full blown hurricane.

I understand you confidence in the models... but the "troughing" you speak of does not exist atm only in the models... and you still forgetting that just two days ago the trough did not even exist in the models and the GFS ran the thing through the NE carrib and into Florida. for all we know this thing takes 5 days to develop into a weak TS and by then its nearing 55 west south of 20n and still traveling west because its was a weak system the whole time. so ask your self what would the models do then? or what would the models do if that low off the east coast transitions to a warm core system since its supposed to sit there for a few days? what happens if the shear over the NE carrib does not move out of the way and we have a sheared weak system ? there is just too many question that cant be answered because first of all there is no tropical cyclone and secondly models are terrible with intensity and with upper level features. my whole point in all this ramblings that there is a whole lot of "certainty" talk the last couple days and for the people that are fairly new to all this might take it literally and learning the wrong things about models... Hence why I said the focus should be on current analysis of the system and instead of speculation on long range models we should all be making a series of short term forecast ( 12 to 48 hours out at most ) on the current organizational progress of the system which will provide a much improved picture of downstream possibilities. I just have to add this one last thing in here them im done preaching lol ... if you dont think the focus should be on a series of short term forecast? then i ask you this.... Why do you think the NHC and most agencies only go 48 hours out in their outlooks during the organization and developments stages of an area of interest?

[ronjon]

Aric true but the troughing is strong, even if the models reduced it it really woulsdn't make a huge amount of difference to the track.

Also this is such a progressive pattern aloft to get to the US it'd probably have to bypass 2-3 troughs and even if it did manage to sneak past the 1st without recurving, the 2nd will almost certainly pick it up.

Its one of the few times I feel VERY confident about the track recurving, normally I'd be very cautious but there is a huge amount of room for error here...If the weakness was strong enough to lift out a sheared very weak closed circulation such as 93L...there is no chance it misses a full blown hurricane.

Actually KWT, the pattern depicted by the models doesn't look progressive at all - its blocked up with the trough and huge low getting stuck off the mid-atlantic coast for literally 5-7 days!

[Tampa Bay Hurricane]

The area in the eastern Atlantic may become something...but it is going to eventually
have to battle a lot of dry air...most of the Atlantic is covered in dry air.

[ronjon]

Moving NW according to the NHC, actually looks a little too far east for my liking, I bet we may see a little bit of a westward adjustment but somewhere close to 60W looks a good call right now...

The troughing will probably recurve all CV systems this year, its VERY impressive...

Um, no. You're still ignoring the fact of the deeply negative NAO we are heading into. If this system does recurve, the next one likely won't.

You do know a -ve NAO promotes LOW pressure over the subtropics right?

Thats why the troughing has been digging down like it has, because we've had a -ve NAO which has meant the jet has been diving southwards over the E.US/W.Atlantic and also sadly for me, right over W.Europe. Inbetween is a decent ridge hence why this heads west till 40-45W but once past that troughing becomes dominant.

Well all I can say is that the negative NAO can just as easily change to positive over the next 2 weeks. Some of you will remember in 2004, all the east coast troffing in early-to-mid August (i.e. Charlie) that flipped around to strong ridging in late August and stayed that way through September. So you never know.

[cycloneye]

The area in the eastern Atlantic may become something...but it is going to eventually
have to battle a lot of dry air...most of the Atlantic is covered in dry air.

The Tropical Atlantic is moisting up as time goes by. The red represents moist air.

[pepeavilenho]

Ohh, god!
When are they going to activate the Invest!

I't'll be interesting to see dynamic models....

[floridasun78]

tooo early to call it a fish Aric Dunn i agree with dont jump gun yet

[gatorcane]

Aric true but the troughing is strong, even if the models reduced it it really woulsdn't make a huge amount of difference to the track.

Also this is such a progressive pattern aloft to get to the US it'd probably have to bypass 2-3 troughs and even if it did manage to sneak past the 1st without recurving, the 2nd will almost certainly pick it up.

Its one of the few times I feel VERY confident about the track recurving, normally I'd be very cautious but there is a huge amount of room for error here...If the weakness was strong enough to lift out a sheared very weak closed circulation such as 93L...there is no chance it misses a full blown hurricane.

The only way it won't recurve is if it threatens Bermuda, but even that looks like it may not even happen there is so much troughiness.

I understand you confidence in the models... but the "troughing" you speak of does not exist atm only in the models... and you still forgetting that just two days ago the trough did not even exist in the models and the GFS ran the thing through the NE carrib and into Florida. for all we know this thing takes 5 days to develop into a weak TS and by then its nearing 55 west south of 20n and still traveling west because its was a weak system the whole time. so ask your self what would the models do then? or what would the models do if that low off the east coast transitions to a warm core system since its supposed to sit there for a few days? what happens if the shear over the NE carrib does not move out of the way and we have a sheared weak system ? there is just too many question that cant be answered because first of all there is no tropical cyclone and secondly models are terrible with intensity and with upper level features. my whole point in all this ramblings that there is a whole lot of "certainty" talk the last couple days and for the people that are fairly new to all this might take it literally and learning the wrong things about models... Hence why I said the focus should be on current analysis of the system and instead of speculation on long range models we should all be making a series of short term forecast ( 12 to 48 hours out at most ) on the current organizational progress of the system which will provide a much improved picture of downstream possibilities. I just have to add this one last thing in here them im done preaching lol ... if you dont think the focus should be on a series of short term forecast? then i ask you this.... Why do you think the NHC and most agencies only go 48 hours out in their outlooks during the organization and developments stages of an area of interest?

Aric, I have to agree with KWT, this is a shoe-in recurve should it develop as we are out about 5 days or so when models start the recurve, out 7 days and the large trough develops across the Western Atlantic. Both the ECMWF and GFS continue to trend towards a recurvature as does the CMC. The model consensus is just too good at this point you can't ignore it, sorry

Need to look to the Caribbean or GOM for any kind of island or US threat, and Western Caribbean for the US more than the Eastern Caribbean. We are in October-mode right now with the troughiness, hard to believe but that is the way it is going....