tornado outbreaks out at sea?

[Terry Tyler]

i was just thinking about something, and it lead me to a question because i honestly dont know the answer to this...

are tornado outbreaks possible out at sea, or tornadic supercells?

i know it seems like a simple enough question, but i know that storms in marine environments function differently then thunderstorms over land...

i wonder like for example out there today, like way off the coast where theres like 3000 cape...would that be a good place that tornadoes could form?

if a strong low-pressure system with good conditions moved out to sea, or came close to sea, could it make the tornadic storms as it would on the land?

 

[Mikey Gribble]

I'm sure there are plenty of tornadoes over the ocean, but the problem with getting mesoscale environments favorable for tornadoes over the ocean is the lack of surface friction. Over land friction slows down wind speeds and causes surface winds to back (since the pressure gradient force is stronger than the Coriolis force). Over the ocean you don't get backing surface winds to the same degree you get over land (because surface friction doesn't slow down the winds speeds so the pressure gradient force and Coriolos force are more balanced and winds tend to follow the isobars) so you typically don't get as good of directional shear, especially in the low levels. Also you typically don't get the levels of instability over the ocean that you do over land. Water does't absorb heat the same way as land. The boundary layer heats up more over land than it does over water. I'm no expert, but those are my thoughts on your question. There are certainly exceptions though, but for the most part the ocean is a less favorable area for tornadoes when compared to land.

 

[Terry Tyler]

I'm sure there are plenty of tornadoes over the ocean, but the problem with getting mesoscale environments favorable for tornadoes over the ocean is the lack of surface friction. Over land friction slows down wind speeds and causes surface winds to back (since the pressure gradient force is stronger than the Coriolis force). Over the ocean you don't get backing surface winds to the same degree you get over land (because surface friction doesn't slow down the winds speeds so the pressure gradient force and Coriolos force are more balanced and winds tend to follow the isobars) so you typically don't get as good of directional shear, especially in the low levels. Also you typically don't get the levels of instability over the ocean that you do over land. Water does't absorb heat the same way as land. The boundary layer heats up more over land than it does over water. I'm no expert, but those are my thoughts on your question. There are certainly exceptions though, but for the most part the ocean is a less favorable area for tornadoes when compared to land.

i appreciate it, mikey...

i was thinking somewhere along those lines, but you really made alot of things clearer with that...its just different out there, but sometimes it happens...

 

[Stephen Levine]

Tornadoes At Sea?

Whereas there may not be many tornadoes, due to the afore mentioned lack of friction, waterspouts descending from TCU and low topped CB's may be relatively common in some areas which might at least give a glimpse of rotating magnificence.

 

[Dan Robinson]

I would think that the surface type (land or water) would have no effect on storm mode or boundary layer wind fields, assuming an identical synoptic environment to one over land. Convection (nor surface winds) doesn't 'care' what the surface type is - the only thing near the surface that it cares about the moisture content at the boundary layer. Backed winds are usually associated with the circulation of a surface low, which, granted, is more likely to form over land (or along the coast) due to baroclinicity.

If the same setup that produces a tornado outbreak over land were to happen over water, I don't think it would be any more or less intense. Given a good wind field, deep boundary layer moisture and instability, what is it going to matter to the supercell that there is water underneath it instead of land?

Due to the lack of radar, damage indicators and visual observations, tornadoes out at sea would be hard to confirm, which probably explains the lack of reports about them. Regardless, there are many documented examples of tornadic supercells at sea observed on radars along the coast - some of which have moved inland.

See:
http://video.google.com/videoplay?docid=-6466225073562924397

 

[Jeff Miller]

I have seen satellite imagery of intense supercellular Cb's over the oceans. Now of course to prove tornadoes existing is another story - but it is absolutely true that - in this scenario (not referring to land based sups in the plains) - supercells have no care about surface type - land or water - just boundaries.

Supercells can die due to wind shifts as the supercell is APPROACHING oceans due to seabreeze, etc - or a temperature change - but if the conditions are right, you'll have a sup and possible tornado. I've also seen dramatic development of supercells as a thunderstorm goes from land to sea.

Here's a tornadic waterspout at sea outside of Australia:

http://australiasevereweather.com/temp/1226tv01.jpg

Another tornadic waterspout can be found here:

http://www.ultimatechase.com/Images/Waterspouts/Isalmorada_Tornadic_Waterspout.jpg

 

[scott r currens]

That is a great question Terry. There are defiantly non-mesocyclone/waterspout outbreaks at sea but I gather your question is referring to supercell tornado outbreaks at sea. For the reasons that Mikey mentioned I think they are not very common but on occasion do occur. Unfortunately there is no way to know for sure. The only examples of possible outbreaks at sea that I am aware of were in the Gulf of Mexico a few years ago. I remember 2-3 days in a row during Feb or Mar that produced several supercells off the coast of Texas with impressive radar signatures from Houston and Corpus Christi.

 

[Mikey Gribble]

Dan said...
"I would think that the surface type (land or water) would have no effect on storm mode or boundary layer wind fields, assuming an identical synoptic environment to one over land. Convection (nor surface winds) doesn't 'care' what the surface type is - the only thing near the surface that it cares about the moisture content at the boundary layer. Backed winds are usually associated with the circulation of a surface low"

Oh I assure you Dan it does matter what surface type you are over. Assuming ALL the atmospheric conditions are the same, no a storm doesn't care and it will act the same. That is why I said "mesoscale environments" favorable for tornadoes are less frequent over water.
Surface features aren't going to influence storm mode directly, but it influences the boundary layer winds and the boundary layer winds effect the storm mode, so yes the surface winds do care about what surface they are over. It is a fact that surface friction will upset the geostrophic balance of the winds and back winds toward the low pressure center. Over land you have more friction than you do over water. The Coriolis force will be weaker over land due to the decreased wind speeds (Coriolis force is proportional to wind speeds), hence the pressure gradient force will be relatively stronger over land and cause backing surface winds (better directional shear for tornadoes in the low levels). Over water you basically have a geostrophic wind at the surface (balance between the pressure gradient force pulling the wind to the left and the Coriolis force pulling the wind to the right), so the winds follow the isobars (lines of equal pressure).
There are tons of other things that are influenced in the same way. Hurricanes moving over land always die rapidly. One of the reasons this happens is because the increase in friction at the surface. Over water the winds circle around the low pressure center at the surface. Once it moves over land friction increases and surface winds back, turning more towards the center of the low pressure. The low pressure center fills and the hurricane dies (pressure gradient decreases). There are other things that kill off hurricanes over land, but this is one thing and another example of the frictional affects of land on the boundary layer winds.
Another example is lake effect snow. There is less friction for the winds traveling over water so the winds are blowing faster. The winds slow down where they encounter land and friction. You get an area of convergence from this and convection in some cases (once again there are other reasons for lake effect snow).
I also stated how you typically don't get as much instability over water as you do over land and that is because of the boundary layer not heating up as much/as quickly. A good example of this differential heating is the land sea breeze.

Dan said...
"Backed winds are usually associated with the circulation of a surface low, which, granted, is more likely to form over land (or along the coast) due to baroclinicity"

If you take that same surface low Dan and put one over water and one over land, the one over land is going to have more backed surface winds for the reasons I explained above. I promise you this is true. These are not my thoughts and ideas. It is well documented meteorological fact and it has nothing to do with baroclinicity.

Like I said in my first post, there are obviously mesocyclone tornadoes over water, but they are less frequent. It's not because "the storm cares about what surface it's over". The storm most certainly doesn't know or care what surface it's over. They are less frequent over water because the mesoscale environments that favor tornadic supercells are less frequent over water. Relatively speaking, surface winds don't back as much over water and you don't get as much instability (due to lower boundary layer heating). This is physics and I promise you it's true. I didn't make this stuff up myself.

 

[Paul Austin]

Well, one thing you don't often have over water: a nice dryline setup .

I'm no expert, but I think weaker lapse rates often become a hinderance to explosive initiation. But as for storm mode; I think as Dan mentioned, with all the right ingredients, tornadic supercells can and do form over water. I remember a few years ago watching radar loops of an isolated cell in the Gulf south of Appalachicola track east for several hours before making landfall with 2+ inch diameter hail. The storm had a persistent couplet on SRM scans, but nothing was confirmed. And this was certainly not an outbreak by any measure.

As for the Gulf, I think a typically weaker upper air Jet also contributes to a likely infrequency of large-scale events.

(Feel free to correct me. Maritime atmosphere is not my bag )

 

[scott r currens]

It would be interesting to see what a nice cold core setup in the Winter/early Spring could produce over the GOM. Anyone have a fast boat or plane
we can chase in?

 

[Gerard Jebaily]

Let us not forget the supercells embedded in the outter bands of tropical systems. I have personally seen waterspouts form out of these cells associated with TS. One waterspout in particular was filmed near key west that i saw video of. A very thick (almost wedge) funnel. I wish i could find the video of it. I have no doubt that tornadic supercells can and do form in open ocean.

Edit: My first "tornado" chase were tornadic waterspouts in the florida keys in a boat. There were 3 down at once associated with a very violent and large thunderstorm. Not the kind of spouts that form from Cu. Not a safe or fun way to chase cause ur out in the weather.

 

[Anna Lindstrom]

I think this is a very interesting topic i remember seeing a waterspout or tornado as they call it, on tv from the volvo ocean race 2001-2002.
This event occurred on "Leg 3" from Sydney to Hobart Tasmania.
There was also golf ball size hail.

I found this video from the ocean race, it´s in german but the video speaks for itself and two articles about it.
The video is of the same waterspout as the picture that Jeff Miller posted.

video:
http://youtube.com/watch?v=VhJS49_W6b4

Articles:
http://edition.cnn.com/2001/WORLD/sailing/12/28/ppl.twister/index.html
http://archives.cnn.com/2001/WORLD/sailing/12/27/sydney.spt/index.html

Anna

 

[Terry Tyler]

It would be interesting to see what a nice cold core setup in the Winter/early Spring could produce over the GOM.

thats precisely the kind of thinking i was thinking when i thought of this question...

im positive you could get a couple good supercells going...even with the lack of surface friction...

ive seen some crazy satellite images of some crazy looking storms out there in the middle of the ocean...

infact, if your talking non-meso tornadoes...im sure, not neccisarily with this particular set-up...but you might even see more water spouts then tornadoes on a plains type set-up...

i dont know a whole lot about waterspouts, but my current understanding is that non-mesocyclone waterspouts form alot easier then a mesocyclone tornado...infact, ive seen several photos with up to three tornadoes out of one storm...

imagine if all those conditions come together, im sure a major waterspout outbreak is possible...

 

[Donald Giuliano]

Let us not forget the supercells embedded in the outter bands of tropical systems. I have personally seen waterspouts form out of these cells associated with TS. One waterspout in particular was filmed near key west that i saw video of. A very thick (almost wedge) funnel. I wish i could find the video of it. I have no doubt that tornadic supercells can and do form in open ocean.

I've seen this video as well, it was from a storm associated with Hurricane Wilma in 2005. Not sure where to find it any more, but there's a picture of the spout on NWS Key West's website--although large barrel is a more apt description, and IIRC it was a wedge at some point during the video you mentioned.

http://www.srh.noaa.gov/key/HTML/wilma/wilma.html

 

[Chris C Sanner]

Wow, that tornadospout (whatever you want to call it) definitely looks to be 1/4-1/2 mi wide at least. This is an interesting topic that I was thinking of when I was down in Galveston this past October. The real question is, who is going to be the first person to actually try to do some major 'field' research on this?