STORM2K

It seems like every year now something subtropical spins up in the Atlantic. I was wondering why the NHC thinks that something not purely tropical should be named? Since a true hurricane is barotropic, I do not understand why something not barotropic should be named. Would any like to explain the reasoning behind naming subtropical systems?

captainbarbossa19 wrote:It seems like every year now something subtropical spins up in the Atlantic. I was wondering why the NHC thinks that something not purely tropical should be named? Since a true hurricane is barotropic, I do not understand why something not barotropic should be named. Would any like to explain the reasoning behind naming subtropical systems?

Subtropical Cyclones were first named by the NHC in 2002, they have a well-defined center & a warm core like Tropical Cyclones, but a asymmetric wind field (Also includes the convection pattern) & strongest winds are over 60 Nautical Miles from the Center, like non-tropical systems . . .

Iceresistance wrote:

captainbarbossa19 wrote:It seems like every year now something subtropical spins up in the Atlantic. I was wondering why the NHC thinks that something not purely tropical should be named? Since a true hurricane is barotropic, I do not understand why something not barotropic should be named. Would any like to explain the reasoning behind naming subtropical systems?

Subtropical Cyclones were first named by the NHC in 2002, they have a well-defined center & a warm core like Tropical Cyclones, but a asymmetric wind field (Also includes the convection pattern) & strongest winds are over 60 Nautical Miles from the Center, like non-tropical systems . . .

I understand what they are, but my question is why name it if it is not truly tropical?

I might get some flack for this, but they also inflate the amount of Atlantic named systems compared to the other basins. I may be mistaken, but no other basin/RSMC names or cares about sub tropical systems -- despite the potential for these systems to be threats to ships and coastal areas etc.

I think this is a decent explanation provided by the NHC back when Andrea formed two years ago:
 https://twitter.com/NWSNHC/status/1132003675214364672




So basically a big reason why is because it's helpful for shipping interests, although with 90L it may pose a threat to Bermuda as well (I believe the Bermuda Weather Service already issued a Tropical Storm Watch) so there's that.

Most of them eventually become fully tropical. There's only been a small handful that under the old policy would never have been named at some point. Though Sandy wasn't subtropical, I imagine that a big subtropical storm could easily strike the East Coast someday and cause similar impacts and justify the naming policy.

So I appreciate all of the answers for my question. I understand that the NHC would want to warn maritime traffic about storms, but is giving a hurricane name to something not truly tropical the only way to accomplish this? Since we are having so many named subtropical storms these days, perhaps the NHC should introduce a new system of classification for them? What do y'all think?

captainbarbossa19 wrote:So I appreciate all of the answers for my question. I understand that the NHC would want to warn maritime traffic about storms, but is giving a hurricane name to something not truly tropical the only way to accomplish this? Since we are having so many named subtropical storms these days, perhaps the NHC should introduce a new system of classification for them? What do y'all think?

I know the NHC and the CPHC don't name them in the EPAC and CPAC. I think the JMA and JTWC in the WPAC don't name them as well. For some reason. Subtropical storms seem to only be called in the Atlantic. So if that's the case, I feel like they should have their own classification system.

As a former marine forecaster (wind & waves)I cannot see how giving a low pressure area that is clearly visible and predicted by the models a name helps in predicting its waves for ships. Ships are easily routed around non-tropical lows. We can see the low (as forecasters). Models see the low. Waves are predicted based on its wind field, not on whether it has a name. I don't remember the real reason the NHC started giving these types of low names in 2002. Most likely, the reason was that such a storm impacted land (perhaps East U.S. Coast in the 1990s) and residents thought they weren't given enough warning about tropical storm conditions since the storm didn't have a name. Some residents may not have paid much attention to an unnamed storm. Naming a storm makes it seem more threatening.

Kingarabian wrote:I might get some flack for this, but they also inflate the amount of Atlantic named systems compared to the other basins. I may be mistaken, but no other basin/RSMC names or cares about sub tropical systems -- despite the potential for these systems to be threats to ships and coastal areas etc.

Ya but that's no surprise as the NHC isn't a global body.

toad strangler wrote:

Kingarabian wrote:I might get some flack for this, but they also inflate the amount of Atlantic named systems compared to the other basins. I may be mistaken, but no other basin/RSMC names or cares about sub tropical systems -- despite the potential for these systems to be threats to ships and coastal areas etc.

Ya but that's no surprise as the NHC isn't a global body.

Well like I said earlier, I have no problems with these being named. it's just odd that they're allowed to be included in the season totals when other basins don't consider them at all. I'm talking about systems that remain subtropical and never gain tropical characteristics of course.

Not directed at anyone in particular ...

Why does it matter? It's not like hurricane season is a game and somehow more numbers indicate a better basin, or a better season. Right?

I'll ask again; explain the science behind naming a storm?

Explain how you would objectively handle the transition of an STS to a fully tropical system.

Explain how you would objectively handle a near hurricane strength STS transitioning to fully tropical near land?

If anything the decision to name STS seems to be a way to remove subjectivity from having to decide when to name a hybrid storm near the coast.

https://www.weather.gov/source/zhu/ZHU_Training_Page/tropical_stuff/sub_extra_tropical/subtropical.htm

I feel like the biggest problem I have with the current system is that when reviewing a season once it is over, the total number of storms will tend to be higher than average when considering both tropical and subtropical systems. I have read many statements from different people saying, "the season is starting earlier and earlier." Others have said, "we are having so many more storms of late." While these statements are technically true, one must remember that a big reason why this is happening is due to the current system of classification. Naming subtropical storms is most certainly aiding the early season count. Most storms named before June 1 are subtropical in nature. Some may transition to tropical (Ana), but many do not. My main point is that while the current system may have good intentions about warning others about an impending storm, it is also creating a new false perception among many that we are having more activity and more early season activity.

wxman57 wrote:As a former marine forecaster (wind & waves)I cannot see how giving a low pressure area that is clearly visible and predicted by the models a name helps in predicting its waves for ships. Ships are easily routed around non-tropical lows. We can see the low (as forecasters). Models see the low. Waves are predicted based on its wind field, not on whether it has a name. I don't remember the real reason the NHC started giving these types of low names in 2002. Most likely, the reason was that such a storm impacted land (perhaps East U.S. Coast in the 1990s) and residents thought they weren't given enough warning about tropical storm conditions since the storm didn't have a name. Some residents may not have paid much attention to an unnamed storm. Naming a storm makes it seem more threatening.

I suspect that this was also part of the reasoning behind naming these subtropical systems. I believe there could be a better way of alerting the public besides using a name from the hurricane list for these systems. If the purpose is to make a storm sound more threatening, that can also cause problems if the storm is not as severe as predicted. Many people will not listen to warnings if they believe the danger is less than reality.

Kingarabian wrote:I might get some flack for this, but they also inflate the amount of Atlantic named systems compared to the other basins. I may be mistaken, but no other basin/RSMC names or cares about sub tropical systems -- despite the potential for these systems to be threats to ships and coastal areas etc.

I'm am very late to the party, but apparently the SIO names some subtropical depressions (they're called depressions but some of them are estimated to have higher winds than some of the TSs and some of them also aren't named so it seems MeteoFrance calls every subtropical system a depression because I can't find one that they call a subtropical storm). Examples are 2012's Dando (fun fact: there was another, weaker, STD that season that wasn't named, so naming probably follows tropical systems like the NHC), 2016's Bransby, and most recently, this year's Issa. I don't think any other basins name subtropical storms, however.

Issa killing 400 people just states why naming subtropical storms is useful...

captainbarbossa19 wrote:So I appreciate all of the answers for my question. I understand that the NHC would want to warn maritime traffic about storms, but is giving a hurricane name to something not truly tropical the only way to accomplish this? Since we are having so many named subtropical storms these days, perhaps the NHC should introduce a new system of classification for them? What do y'all think?

There's an interesting answer to that actually. The "subtropical" designation is actually the 'updated' system from the 1960s/70s, where they were referred to as 'neutercanes' and named using the phonetic alphabet--Alfa, Bravo, Charlie, etc. 1976 appears to have been the first year in which subtropical storms weren't named, but often advisories were still issued and other times they were added post-season. But they were always counted in the storm total.

As for the apparent increase, that seems more a result of activity moving more towards the subtropics in general--compare 1995 and 96 to 2000 and 01 for instance, and the drastic increase in storms that formed in the subtropics. There were quite a few storms that were classified (even operationally) as subtropical--two in each year and several others that had a subtropical portion added to the early track.

If anything changes, they need to start using the subtropical designation on storms that were previously tropical--storms such as Gabrielle in 2001 after Florida, and Dennis in 1999 off the Carolinas, using that period as reference--rather than keeping it tropical the entire time.

To the larger question, it's more practical to have one single naming list, and not naming a system (subtropical storms aren't just weak systems--there have been quite a few near the coast at near hurricane intensity) might imply it is less threatening than a weak tropical storm that is named.

Subtropical storms are also barotropic and don't have fronts extending into them. They were included in the naming system in 2002 but were recognized by the NHC long before then. For a time they were given phonetic letters(like Alfa). They have a shallow warm core and bring tropical storm like conditions, so why not name them? On one recorded occasion, a subtropical system became a minimal subtropical hurricane (the only on record). Many north atlantic subtropical systems, if not the majority, transition into tropical.

TWC has started to name non-tropical frontal lows, but the challenge in doing so officially through NOAA is that one system is not necessarily distinct from the next that forms along the frontal trough. Also they form continuously. Subtropical lows are distinct, sporadic, and isolated; and therefore nameable rather than a frontal system that reaches the same intensity.

If we name tropical storms that spin up late season in the mid-Atlantic or highly sheared waves that manage to briefly organize, why not subtropical? The NHC didn't know what to call them at first, but understood their dynamics (much like medicanes which will probably be classified as something more official in the future). I don't disagree with the current naming system. Perhaps one that includes a separate list for subtropical systems(as we had before) would be preferable scientifically as subtropical storms aren't counted in ACE and many other tropical cyclone stats, but that would confuse the public. The system would then have to get a new name once it becomes tropical, which would confuse some people. If you start talking about subtropical storm Bravo and then it's suddenly hurricane Victor, then people may not catch on and may think it is a different system somewhere else. Less risk of that with the internet, but a risk nonetheless.