Why I'm concerned about 2007 season

[Stratosphere747]

AFM,

Could you better explain the differences between the SST's maps vs. the TCHP maps. I've always been very dismissive of the TCHP maps and how they truly correlate to potential influences on a tropical system.

[Air Force Met]

AFM,

Could you better explain the differences between the SST's maps vs. the TCHP maps. I've always been very dismissive of the TCHP maps and how they truly correlate to potential influences on a tropical system.

SST's are just that...the temp of the water at the sfc. TCHP is the total heat content of ocean. Think of SST's as your octane and think of TCHP as how much gas there is in your tank. TCHP is calculated by using depth of the water and temps.

So...if you have 86F water...but it is real shallow and very cold right underneath the sfc...you have high octane gas but not much in the tank. So...you can't go very far. If you have 80F water...and it's deep...then you have low octane gas...and you can't go fast...but its sustainable because you have a full tank. If you have 86F water that is deep...that willgive you a high TCHP...maybe over 80 kj/Cm2. That will let you go fast...and for a long time...like Katrina...Rita...Wilma...Mitch...

You get the picture. TCHP is very important. It's the fuel that fuels the race car. The higher the number...the faster and longer you can run.

[Stratosphere747]

AFM,

Could you better explain the differences between the SST's maps vs. the TCHP maps. I've always been very dismissive of the TCHP maps and how they truly correlate to potential influences on a tropical system.

SST's are just that...the temp of the water at the sfc. TCHP is the total heat content of ocean. Think of SST's as your octane and think of TCHP as how much gas there is in your tank. TCHP is calculated by using depth of the water and temps.

So...if you have 86F water...but it is real shallow and very cold right underneath the sfc...you have high octane gas but not much in the tank. So...you can't go very far. If you have 80F water...and it's deep...then you have low octane gas...and you can't go fast...but its sustainable because you have a full tank. If you have 86F water that is deep...that willgive you a high TCHP...maybe over 80 kj/Cm2. That will let you go fast...and for a long time...like Katrina...Rita...Wilma...Mitch...

You get the picture. TCHP is very important. It's the fuel that fuels the race car. The higher the number...the faster and longer you can run.

Good stuff. I knew it was based on the depth of the water, and seems over the last few years that has become a better understanding from tropical mets.

Makes sense as well when you see maps posted earlier by Jschlitz and myself showing high SST's over certain portions of the GOM, but lower TCHP levels.

[Air Force Met]

Makes sense as well when you see maps posted earlier by Jschlitz and myself showing high SST's over certain portions of the GOM, but lower TCHP levels.

...And that is because SOL hasn't had time to warm up anything but the sfc yet. It takes a while for that 86 degree water to work it's way down 200 feet...especially given the tendency for warm water to rise to the top.

You see the same thing in swimming pools. In May it is real warm at the sfc on a calm day...but a little nippy at the bottom.

[Stratosphere747]

Makes sense as well when you see maps posted earlier by Jschlitz and myself showing high SST's over certain portions of the GOM, but lower TCHP levels.

...And that is because SOL hasn't had time to warm up anything but the sfc yet. It takes a while for that 86 degree water to work it's way down 200 feet...especially given the tendency for warm water to rise to the top.

You see the same thing in swimming pools. In May it is real warm at the sfc on a calm day...but a little nippy at the bottom.

Would this be a better map to look at for those that seem to focus on SST's compared to TCHP? Or I'm I misreading it? It's not as detailed as the SST's maps the we have, but does show a different perspective.

https://www.navo.navy.mil/cgi-bin/graph ... 5/0-0-17/2

[cpdaman]

STU ostro put out a report that el nino caused higher shear in atlantic waters and when there is no el nino (not even a la nina) but a lack of an elnino conditions are more ripe for development in the atlantic and add warm water and you have storms IMO

[Ptarmigan]

SST's mean very little. It's all about heat content. If all other ingredients are equal...the TCHP has the capability of taking a Cat 2 and turning it into a Cat 5.

So...with that in mind...let's compare years...at this current date:

June 13th, 2007

June 13th, 2006

June 13th, 2005

You can see the head start in TCHP we had in 2005. We are not even close to that now...but slightly ahead of 2006...especially in the NW Caribbean and SE GOM.

2005 had much higher heat content than 2006 and right now.

[Steve]

Nice post j. I had lost my link to the gulf Super High Res. I don't disagree with those who noted the importance of heat content in the overall picture (AFM). But I disagree that the SST's are essentially meaningless. I'm not buying that at all. I'm not going to come on and say that all things being equal, you can watch the future trails of systems, but there have been years (most recently 2005), that you can almost take it to the bank. I'm not going back to do the research, but it's all back in the archives here. I was talking about the MS coast by early June. We had Cindy and Dennis in the vicinity, but even they didn't sap all the available content. As the loop current stayed super hot, it remained clear to me (as I also noted) that I'd be super worried if I was on the MS or AL gulf coasts still. It's not like the hot water is necessarily a magnet, but it should throw up caution flags for any storm watchers. And following the evolution of water temperatures will lead to some hints as the season progresses (specifically as concerns potential strength of systems in a given area).

Steve

[Scorpion]

It's all about shear and dry air more than anything. As long as conditions are favorable(and they should be come August) then high octane storms will form.

[Duddy]

This image speaks 1,000 words:

Your worried because the water in the Gulf is orange flavored?

[Frank2]

I don't have an image, but, as seen on the local weather this morning, the Gulf is home to some very dry air at this time...

[Thunder44]

Nice post j. I had lost my link to the gulf Super High Res. I don't disagree with those who noted the importance of heat content in the overall picture (AFM). But I disagree that the SST's are essentially meaningless. I'm not buying that at all. I'm not going to come on and say that all things being equal, you can watch the future trails of systems, but there have been years (most recently 2005), that you can almost take it to the bank. I'm not going back to do the research, but it's all back in the archives here. I was talking about the MS coast by early June. We had Cindy and Dennis in the vicinity, but even they didn't sap all the available content. As the loop current stayed super hot, it remained clear to me (as I also noted) that I'd be super worried if I was on the MS or AL gulf coasts still. It's not like the hot water is necessarily a magnet, but it should throw up caution flags for any storm watchers. And following the evolution of water temperatures will lead to some hints as the season progresses (specifically as concerns potential strength of systems in a given area).

Steve

It depends what storms you are really concerned with. If we are talking about weaker systems like TS or minimal hurricanes, they can maintain themselves longer over shallow layer warm water. If you are talking about major hurricanes, you need a deep-layer warm water, because the stronger the winds are, the more upwelling the cause.

[benny]

The Gulf of Mexico is warm every year. All you need to look at is last year to realize that a warm Gulf means nothing about the season. Wind shear is so much more important than any oceanic influence. All you have to look at is the 1950, 1955 or 1964 hurricane season. Water temperatures were below average (in some case way below average) yet the seasons turned out really active. All that being said... if the ssts are above average in the tropical atlantic, you know the subtropical high is weaker than average, which probably means less shear due to weaker trades. It is all connected somehow.

It is too early to really say anything about 2007 as a whole.. but the wind shear has been below average since 1 June. Check out:
http://www.cpc.ncep.noaa.gov/products/hurricane/ and then look at vertical shear 200-850 animation 11 day averages. That is a very active pattern. It will probably change a lot though as all the global convection shifts into indonesia and the western pacific.

[benny]

AFM,

Could you better explain the differences between the SST's maps vs. the TCHP maps. I've always been very dismissive of the TCHP maps and how they truly correlate to potential influences on a tropical system.

SST's are just that...the temp of the water at the sfc. TCHP is the total heat content of ocean. Think of SST's as your octane and think of TCHP as how much gas there is in your tank. TCHP is calculated by using depth of the water and temps.

So...if you have 86F water...but it is real shallow and very cold right underneath the sfc...you have high octane gas but not much in the tank. So...you can't go very far. If you have 80F water...and it's deep...then you have low octane gas...and you can't go fast...but its sustainable because you have a full tank. If you have 86F water that is deep...that willgive you a high TCHP...maybe over 80 kj/Cm2. That will let you go fast...and for a long time...like Katrina...Rita...Wilma...Mitch...

You get the picture. TCHP is very important. It's the fuel that fuels the race car. The higher the number...the faster and longer you can run.

Every year the same debate happens. Heat Content versus SST. Heat content is just way too overtrumped. Lynn Shay at UM will tell you that a mature hurricane needs about 10 units of heat content. A major hurricane maybe double. That's it. In a seasonal forecast... heat content is irrelevant. Whether the heat content is 30 or 130.. as long as the atmosphere is producing low shear, the hurricane will probably get stronger. Now it may get stronger faster at the 130 value... but it is no guarantee. I would argue that we don't understand why some hurricanes love to intensify over the extremely high heat content over the w carib... while others, like Hurricane Isabel in 2003, will intensify to Cat 5 status over low heat content.

The number one predictor in the ships model is SST. Heat content is some fourth order factor that is imporant in some cases when it is a rather high value. In a statistical sense, that's how the importance falls out.

I guess there are times when heat content is important. One of them is when a hurricane is rather slow moving. If the storm is over lower heat content, it can upwell cooler water to the surface and cause weakening. Higher heat content won't have that same effect. There are some signs that during rapid intensification heat content can influence the process. But otherwise... heat content is really a red herring in my opinion. It can be important in some specialized situations. But most of the time, the importance of the SSTs far outweight the integrated depth for intensity change information.

[Air Force Met]

The number one predictor in the ships model is SST. Heat content is some fourth order factor that is imporant in some cases when it is a rather high value. In a statistical sense, that's how the importance falls out.

I guess there are times when heat content is important. One of them is when a hurricane is rather slow moving. If the storm is over lower heat content, it can upwell cooler water to the surface and cause weakening. Higher heat content won't have that same effect. There are some signs that during rapid intensification heat content can influence the process. But otherwise... heat content is really a red herring in my opinion. It can be important in some specialized situations. But most of the time, the importance of the SSTs far outweight the integrated depth for intensity change information.

...And we all know how accurate the SHIPS model is...

But the DSHIPS uses TCHP....and it is a better model.

We will have to disagree on the heat content. I do not beleive it is a red herring...and there are a lot of guys at the NHC who don't believe so either. Can a storm develop over lower TCHPs? Sure. But the evidence of storms undergoing exposive deepening when hitting a pool of high TCHP is tremendous. Some storms do undergo exposive deepening without the high TCHPs...given IDEAL environmental factors...but the NHC and AOML/HRD have done extensive research on this and have concluded that all things equal, 86F SSTs with a high TCHP will lead to a stronger storm than 86F SSts with lower TCHPs. 80 kJ/cm2 seems to be the magic number. Opal, Mitch, Ivan, Bret, Wilma, Katrina, Rita...they all have one thing in common...they went boom over higher TCHP's...and some started to poop out when they left those high TCHPs....like Rita.

So...while TCHP is not the end all...it...is IMO...a piece of the puzzle that fits in with the rest of the factors: Shear, moisture, SSTs, land interaction, eyewall cycles...etc...to give an overall forecast of filling of deepening.

To say...as you did...that it is a red herring....is IMO...scientifically irresponsible. To say that something is a red herring means you believe it is extraneous data and that this information is not necessary at all. After all, that is what the term red herring means. I disagree with that assumption. I am not saying that TCHP is the most important pice of evidence in solving the intensification puzzle...but that it is an important piece...especially in terms of exposive cyclogensis. Researchers at the NHC and the HRD support that opinion.

[benny]

The number one predictor in the ships model is SST. Heat content is some fourth order factor that is imporant in some cases when it is a rather high value. In a statistical sense, that's how the importance falls out.

I guess there are times when heat content is important. One of them is when a hurricane is rather slow moving. If the storm is over lower heat content, it can upwell cooler water to the surface and cause weakening. Higher heat content won't have that same effect. There are some signs that during rapid intensification heat content can influence the process. But otherwise... heat content is really a red herring in my opinion. It can be important in some specialized situations. But most of the time, the importance of the SSTs far outweight the integrated depth for intensity change information.

...And we all know how accurate the SHIPS model is...

But the DSHIPS uses TCHP....and it is a better model.

We will have to disagree on the heat content. I do not beleive it is a red herring...and there are a lot of guys at the NHC who don't believe so either. Can a storm develop over lower TCHPs? Sure. But the evidence of storms undergoing exposive deepening when hitting a pool of high TCHP is tremendous. Some storms do undergo exposive deepening without the high TCHPs...given IDEAL environmental factors...but the NHC and AOML/HRD have done extensive research on this and have concluded that all things equal, 86F SSTs with a high TCHP will lead to a stronger storm than 86F SSts with lower TCHPs. 80 kJ/cm2 seems to be the magic number. Opal, Mitch, Ivan, Bret, Wilma, Katrina, Rita...they all have one thing in common...they went boom over higher TCHP's...and some started to poop out when they left those high TCHPs....like Rita.

So...while TCHP is not the end all...it...is IMO...a piece of the puzzle that fits in with the rest of the factors: Shear, moisture, SSTs, land interaction, eyewall cycles...etc...to give an overall forecast of filling of deepening.

To say...as you did...that it is a red herring....is IMO...scientifically irresponsible. To say that something is a red herring means you believe it is extraneous data and that this information is not necessary at all. After all, that is what the term red herring means. I disagree with that assumption. I am not saying that TCHP is the most important pice of evidence in solving the intensification puzzle...but that it is an important piece...especially in terms of exposive cyclogensis. Researchers at the NHC and the HRD support that opinion.

Well let me clarify my statement then. Red herring is perhaps too strong. However, heat content is nowhere near the top of the list of things that are important for TC intensification. People are focusing all their time and energy on heat content, when in fact many storms intensify and become major hurricanes over very low heat content water. Isabel and Kate of 03 are good examples. Storms need less than 20 units of heat content to become major hurricanes. This is a fact. Some storms reach their potential but most do not. Why? Because of atmospheric factors. Anything going on in the inner core or environment is 90% of the equation. Heat content is not even a predictor for rapid intensification in the Demaria/Kaplan scheme. SST is the predictor (well actually MPI, but that doesn't use heat content either). Why? Because fast intensification happens over water temps above 26C all of the time.

I think heat content is one of those things that is overemphasized. It has the potential to help an intensity forecast in just the right circumstance, if the atmosphere and other inner core processes will let it. I think it is useful in a slow-moving storm, then upwelling will be a bigger factor. It is a contributor to RI for sure. But when you look at the raw stats of all storms, it just isn't a big factor. Does it matter whether a storm is Cat 5 Isabel or Cat 5 Katrina? The heat content couldn't have been more different.

Also, to correct some errors above, SHIPS (and DSHIPS) uses the SST first. They are basically the same thing except for the landfall information. Both of the model use both pieces of info (SST, heat content) but SST is much more important.

Take a look at:
ftp://ftp.tpc.ncep.noaa.gov/atcf/archiv ... _ships.txt

There is no heat content information in the rapid intensification index. Also look at how minor a factor that the heat content shows up as in the output of SHIPS. For example, in 36 hours, SST potential is contributing 10 kt, Shear is contributing 12 kt, and ocean heat potential is contributing -1 kt. Even in a case with high heat content like Ernesto:

ftp://ftp.tpc.ncep.noaa.gov/atcf/archiv ... _ships.txt

The shear and SST is still far more important. SHIPS may not be perfect, but it is best statistical model out there. In my opinion, heat content should not be taken as a serious limiting factor if the atmosphere is right. It is a piece of the puzzle, but a small piece and not one to fixate on.

[Ptarmigan]

We should also look at how high and cold these cloud tops are in tropical storms and hurricanes. That is overlooked. One can have a major hurricane over 85 degree water vs. 90 degree water. I know strong hurricanes tend to have high cloud tops and cold temperatures. Wilma had high cloud tops, same with Rita, Katrina, Tip, and Gilbert. I would not be surprised that Epsilon in 2005 had higher cloud tops than most hurricanes normally would have. I also think annular hurricanes like Isabel and Daniel had higher cloud tops than non annular hurricanes.

[Air Force Met]

Well let me clarify my statement then. Red herring is perhaps too strong. However, heat content is nowhere near the top of the list of things that are important for TC intensification. People are focusing all their time and energy on heat content, when in fact many storms intensify and become major hurricanes over very low heat content water. Isabel and Kate of 03 are good examples. Storms need less than 20 units of heat content to become major hurricanes. This is a fact. Some storms reach their potential but most do not. Why? Because of atmospheric factors. Anything going on in the inner core or environment is 90% of the equation. Heat content is not even a predictor for rapid intensification in the Demaria/Kaplan scheme. SST is the predictor (well actually MPI, but that doesn't use heat content either). Why? Because fast intensification happens over water temps above 26C all of the time.

I think heat content is one of those things that is overemphasized. It has the potential to help an intensity forecast in just the right circumstance, if the atmosphere and other inner core processes will let it. I think it is useful in a slow-moving storm, then upwelling will be a bigger factor. It is a contributor to RI for sure. But when you look at the raw stats of all storms, it just isn't a big factor. Does it matter whether a storm is Cat 5 Isabel or Cat 5 Katrina? The heat content couldn't have been more different.

Also, to correct some errors above, SHIPS (and DSHIPS) uses the SST first. They are basically the same thing except for the landfall information. Both of the model use both pieces of info (SST, heat content) but SST is much more important.

Take a look at:
ftp://ftp.tpc.ncep.noaa.gov/atcf/archiv ... _ships.txt

There is no heat content information in the rapid intensification index. Also look at how minor a factor that the heat content shows up as in the output of SHIPS. For example, in 36 hours, SST potential is contributing 10 kt, Shear is contributing 12 kt, and ocean heat potential is contributing -1 kt. Even in a case with high heat content like Ernesto:

ftp://ftp.tpc.ncep.noaa.gov/atcf/archiv ... _ships.txt

The shear and SST is still far more important. SHIPS may not be perfect, but it is best statistical model out there. In my opinion, heat content should not be taken as a serious limiting factor if the atmosphere is right. It is a piece of the puzzle, but a small piece and not one to fixate on.

I have no disagreement with what you are saying in the above. Intensification does happen all the time with TCHP values that are low over high SSTs. And other environmental factors are certainly more important than TCHP. Other environmental factors are more important than SSTs. I think the point you are missing...that I am trying to make...is that TCHP is not an important factor in intensification...but RAPID and explosive cyclogenesis. Sure...many storms can deepen to a cat 3 and above over low TCHPs...but deepening to that level takes energy....as well as great-ideal environmental conditions.

All TCHP is is a measure of available energy. If a given storm needs "X" amount of available thermodynamic energy to deepen to 940 mb...then (given the same atmospheric conditions)...it has the potential to do it much more quickly if it is sitting over an area of 120 kj/cm2 than an area of 10 kj/cm2 (given all other things are equal). That's the issue...not that a storm can get there...but how fast it can get there. Sure a storm can get from a TS to a Cat 5 on 20 KJ/CM2...but it won't do it in 24 hours. Certainly Wilma wouldn't had bombed the way she did if she was sitting over 10 kj/cm2 TCHP. She did it because she was near TCHP of 100 kj/cm2...and her southerly inflow was tapping 130 kj/cm2. NOw...with all of that...sans a perfect environment she would not have bombed either. TCHP helps in that explosive cyclogenesis process. Sure storms can strengthen with high TCHP. BUt...when you want the tank filled up to Cat 4 or 5 rapidly...it helps to have a 24" pipe feeding into the pool and not a water hose.

[wxmann_91]

We should also look at how high and cold these cloud tops are in tropical storms and hurricanes. That is overlooked. One can have a major hurricane over 85 degree water vs. 90 degree water. I know strong hurricanes tend to have high cloud tops and cold temperatures. Wilma had high cloud tops, same with Rita, Katrina, Tip, and Gilbert. I would not be surprised that Epsilon in 2005 had higher cloud tops than most hurricanes normally would have. I also think annular hurricanes like Isabel and Daniel had higher cloud tops than non annular hurricanes.

I actually think the opposite regarding cloud tops for non-annular vs. annular hurricanes. Actually, Isabel's, Epsilon's, and Daniel's cloud tops were not high at all. High cloud tops equate to more thunderstorm activity, which signals that outer eyewalls will more likely form. So that goes against the definition of annular. In addition, annular hurricanes are more likely to form where SST's are marginal, in an environment less instability for those high cloud-top thunderstorms.

SST's are certainly very important... the higher, the more potential energy available to expend in the form of convection. Certainly mid-level temps are also very important, but those usually will not start cooperating until late in the season. TCHP may be a greater factor for mature, strong hurricanes.