Changes in Tropical Cyclone Intensity & Track

[Don C L]

I'm no expert on that area and I only watch it from a distance, but given the pool of heat in the Gulf and what we just saw with Helene, I'd be inclined to hold off for a while if you can.
https://weather.com/storms/hurricane...-early-october

[davil]

thank you, Don
Unfortunately, have to agree with you.
Just wanted to have some feedback.
Sometimes impatience drives regret.
Take care.

David

[GordMay]

“How Strong Can a Hurricane Get?” ~ by Live Science
➥ https://www.livescience.com/32179-how-strong-can-a-hurricane-get.html

Originally Posted by Live Science

“... By the end of the 21st century, human-caused global warming will likely increase hurricane intensity, on average, by 2 to 11 percent, according to a review by NOAA's Geophysical Fluid Dynamics Laboratory, revised on Aug. 30, 2017.

But physics dictates there must be a limit. Based on ocean and atmospheric conditions on Earth nowadays, the estimated maximum potential for hurricanes is about 190 mph* (305 km/h), according to a 1998 calculation by Kerry Emanuel, a climatologist at the Massachusetts Institute of Technology.

This upper limit is not absolute, however. It can change due to changes in climate. Scientists predict that as global warming continues, the maximum potential hurricane intensity will go up. They disagree, however, on what the increase will be. ...”

* By 8 p.m. on Monday [Oct 7], hurricane Milton’s maximum sustained wind speeds had increased to 180 miles per hour, making Milton one of the strongest Atlantic hurricanes ever.



Global Warming and Hurricanes: An Overview of Current Research Results
~ by Tom Knutson, Senior Scientist, NOAA/GFDL
➥ https://www.gfdl.noaa.gov/global-war...nd-hurricanes/

“... Two frequently asked questions on global warming and hurricanes are the following:
- What changes in hurricane activity are expected for the late 21st century, given the pronounced global warming scenarios from IPCC models?
- Have humans already caused a detectable increase in Atlantic hurricane activity or global tropical cyclone activity? ...

... But what does this anthropogenic global warming mean for Atlantic hurricane activity, or global tropical cyclone activity? Here, we address these questions, starting with those conclusions where we have relatively more confidence. The main text of this web page gives more background discussion. “Detectable” change here will refer to a change that is large enough to be clearly distinguishable from the variability due to natural causes. Our main conclusions are: ...”

[GordMay]

Tropical Tornadoes:
Tropical tornadoes are an underrated but extremely dangerous threat in any landfalling storm, whether it’s a weak depression or a sprawling hurricane.

It’s common for tropical depressions, tropical storms, and hurricanes to produce, at least, a couple of tornadoes, whenever they make landfall [and even days afterward].
Thunderstorms require the right balance of moisture, instability, and ample wind shear, in order to produce tornadoes.
There’s no shortage of all three ingredients, when a tropical system makes landfall.

When a hurricane makes landfall, the lower level winds, near the surface, dramatically slow down, as a result of friction. The difference between slower winds near the surface, and stronger winds aloft. leads to wind shear.
This wind shear creates a horizontal rolling motion in the atmosphere. Updrafts, feeding into a thunderstorm, can tilt this horizontal rotation vertically, lending a storm the rotation it needs to produce a tornado. The most favourable wind shear, within a Northern Hemisphere tropical cyclone, occurs in the right-front quadrant of the storm, which is ahead of, and to the right of the eye.

Eg: If a hurricane is moving due east, for instance, the right-front quadrant is the south-eastern side of the storm centre.

[GordMay]

The Fujiwhara Effect

The National Weather Service defines the Fujiwhara Effect as “a binary interaction where tropical cyclones within a certain distance … of each other begin to rotate about a common midpoint.”
That means the two storms interact with, and are shaped by, one another [a binary interaction], rarely, even combining, into one storm.

The concept was born out of the interaction between typhoons in the Pacific Ocean, over a century ago, by Sakuhei Fujiwhara, a Japanese meteorologist, who published his findings about the “tendency towards symmetry of motion”, in 1921.
He described how, when two vortices [spinning objects] approached each other, they would tend to orbit around a common center point. This is applicable to cyclones [hurricanes], because cyclones are types of vortices. During the interaction, if one cyclone is stronger than the other, the weaker cyclone will usually get absorbed. They’ll likely gravitate toward each other, if each cyclone is near the same strength. On very rare occasions, the two cyclones could merge, into one stronger storm.

“The natural tendency towards symmetry of motion and its application as a principle in meteorology” ~ by Sakuhei Fujiwhara [1921]
➥ https://rmets.onlinelibrary.wiley.co...qj.49704720010

GOES-16 satellite imagery over the eastern Pacific Ocean from July 25 to August 1. Hurricane 'Irwin', on the left, collided with Hurricane 'Hilary', on the right; the two merged, before fading out, over the ocean.
➥ https://www.weather.gov/news/fujiwhara-effect

➥ https://www.weather.gov/images/news/170208_GOES-16.gif

[Johan Leopard51]

With all the changes going on, I hope Seychelles (our base), remains virtually hurricane-free. We get some storms, but nothing near like what passes Florida.

Apparently it is because we are 4 degrees from equator and hurricanes don’t like equators

[GordMay]

Originally Posted by Johan Leopard51

With all the changes going on, I hope Seychelles (our base), remains virtually hurricane-free. We get some storms, but nothing near like what passes Florida.

Apparently it is because we are 4 degrees from equator and hurricanes don’t like equators

Since the Corioles force [which imparts the spin to cyclones] is at a maximum at the poles, and a minimum at the equator, hurricanes don't genarally form, within 5 degrees latitude of the equator.

The Corioles force generates a counterclockwise spin, to low pressure, in the Northern Hemisphere; and a clockwise spin, to low pressure, in the Southern Hemisphere.
With little, to no, Corioles force [near/at the equator] the air will simply go straight, from high to low pressure, without rotating. No rotation, no cyclone.

Still, there are rare exceptions. For instance, in 2001, in the South China Sea, Tropical Cyclone “Vamei” intensified, within 2 degrees of the equator, but the nascent circulation actually formed earlier, farther away from the equator. Scientists think winds, interacting with island terrain, in the Indonesian archipelago, may have generated the rotation that gave rise to “Vamei”.

[davil]

Temps are inching down!!!

I am on the boatyard, hoping to go back by the end of October.

Traditionally, hurricane season could include November.

However, looking at the water temps are cooling down considerably with differences as much as 84 Caribbean, 74 Gulf of Mexico and 64 around my area Cape Lookout.

Reason for hope?

[GordMay]

Originally Posted by davil

Temps are inching down!!!

I am on the boatyard, hoping to go back by the end of October.

Traditionally, hurricane season could include November.

However, looking at the water temps are cooling down considerably with differences as much as 84 Caribbean, 74 Gulf of Mexico and 64 around my area Cape Lookout.

Reason for hope?

Current temperatures, per your graphic, seem pretty close to average, for October; but, hope doesn't need a reason.

Average water temperatures [°C/°F] in the Atlantic Ocean
Month: Arctic ~ Tropics ~ Temperate [your region]
October: 1.6°C/34.9°F ~ 28.8/83.9°F ~ 18.1/64.7

[davil]

thanks

thinking will be hard for storms to track over cooler waters?

From

https://www.weather.gov/source/zhu/Z...e_anatomy.html

There are six widely accepted conditions for hurricane development:

1. The first condition is that ocean waters must be above 26 degrees Celsius (79 degrees Fahrenheit). Below this threshold temperature, hurricanes will not form or will weaken rapidly once they move over water below this threshold. Ocean temperatures in the tropical East Pacific and the tropical Atlantic routinely surpass this threshold.

PS
on hope, you are right
Unfortunately, the outcome of hope is dubious at best.

[davil]

Looks like Hurricane Sandy (Sandy October 27-29, 2012)

temps were higher

https://www.google.com/search?q=wate...hrome&ie=UTF-8

During Hurricane Sandy, water temperatures in North Carolina dropped as the storm moved northward, mixing colder deep water with the surface ocean:
Bogue Pier: Water temperatures dropped from 73°F to 67°F in just a few days
Bogue Sound: Water temperatures dropped from 72°F to a season low of 60°F in just a few days
In contrast, when Hurricane Sandy was off the Northeastern coast of the United States, the water temperature was 5.4°F (3.0°C) above average. This was due to global warming, which contributed 1°F (0.6°C) to the abnormally warm sea surface temperatures.
Warm ocean water is a key factor in fueling tropical storms. Hurricanes will not form or will weaken rapidly if the ocean water temperature is below 79°F (26°C).

[GordMay]

Technically, “Sandy” wasn’t a hurricane [tropical cyclone] when it came ashore, near Brigantine, New Jersey, just to the northeast of Atlantic City, on October 29, 2012 - by then, it was an Extratropical Cyclone.
Hurricane “Sandy” was a Category 3 storm, at its peak intensity, when it made landfall in Cuba, though most of the damage it caused was after it became a Category 1-equivalent extratropical cyclone, off the coast of the Northeastern United States [New York].

[Montanan]

Just when you thought it might be safe to go back into the water:

'Do not swim!' Americans issued major 'toxic' algae warning after Hurricane Milton batters Florida



Link:

https://www.msn.com/en-us/news/us/do...7d61dd15&ei=38


Snipet:

"Toxic algal blooms caused by the upwelling from Hurricane Milton and Hurricane Helene are happening around the Tampa Bay Area.
"This is particularly bad for humans and deadly for sea animals. Do not swim in these waters. Unfortunately, this will likely lead to many fish and other sea animals to wash up on shore."

The toxins can be suspended in the air near beaches, posing health risks to people who breathe them in.

Symptoms may include coughing, shortness of breath, and dizziness.

Those with respiratory conditions or autoimmune issues are particularly vulnerable.

[GordMay]

“Emissions Gap Report 2024" ~ United Nations Environment Programme [UNEP, October 24, 2024]
➥ https://www.unep.org/resources/emiss...SAAEgLRafD_BwE

Full Report ➥ https://wedocs.unep.org/bitstream/ha...=3&isAllowed=y

Greenhouse Gas Emmissions must be reduced by 42%, by 2030; and 57% by 2035, to get on track to limit temperature increase to 1.5°C.
A failure to increase ambitions, in the new Nationally Determined Contributions [NDCs], and start delivering immediately, would put the world on course for a temperature increase of 2.6 - 3.1°C, over the course of this century.

Originally Posted by UNEP

“... Greenhouse Gas Emmissions ... cuts of 42 per cent are needed by 2030 and 57 per cent by 2035 to get on track for 1.5°C.
A failure to increase ambition in these new Nationally Determined Contributions [NDCs] and start delivering immediately would put the world on course for a temperature increase of 2.6 - 3.1°C over the course of this century...

... To get on a least-cost pathway for 1.5°C, emissions must fall 42 per cent by 2030, compared with 2019 levels.
For 2°C, emissions must fall 28 per cent by 2030.
Looking out to 2035 – the next milestone after 2030 to be included in NDC targets – emissions must fall 57 per cent for 1.5°C and 37 per cent for 2°C.
As greenhouse gas emissions rose to a new high of 57.1 gigatons of carbon dioxide equivalent in 2023, the cuts required from today are larger; 7.5 per cent must be shaved off emissions every year until 2035 for 1.5°C.
Current promises are nowhere near these levels, putting us on track for best-case global warming of 2.6°C this century and necessitating future costly and large-scale removal of carbon dioxide from the atmosphere to bring down the overshoot ...”

[GordMay]

When researchers, with World Weather Attribution, studied Hurricanes Helen, and Milton [1 & 2], they found climate change made Milton 20 to 30 per cent more intense, effectively pumping it up from a Category 2 to a Category 3 hurricane.

That's how rapid attribution science puts a number to how much humanity's burning of fossil fuels contributes to the strength of an extreme weather event.
Put another way: Climate change is responsible for nearly half the economic damage, from Hurricane Milton.
Considering insured losses from Milton are estimated at $30 billion to $50 billion, it's no small number.
But it's likely a conservative estimate, given that insured losses are just a part of the picture. It's probably about $3 to $4 more [taxpayer cost], for every dollar of insured loss.
Then, there is also the whole social, psychological, and traumatic impacts, of these kinds of events.

Sea level rise – which human activity has very likely been the main driver of, since at least 1971, according to IPCC AR6, should be causing higher coastal inundation levels, for tropical cyclones, that do occur, all else assumed equal.

Tropical cyclone rainfall rates are projected to increase in the future (medium to high confidence) due to anthropogenic warming and accompanying increase in atmospheric moisture content.

Tropical cyclone intensities globally are projected to increase (medium to high confidence) on average (by 1 to 10% according to model projections for a 2 degree Celsius global warming).

The global proportion of tropical cyclones that reach very intense (Category 4 and 5) levels is projected to increase (medium to high confidence) due to anthropogenic warming over the 21st century.

[1] “Climate change key driver of catastrophic impacts of Hurricane Helene that devastated both coastal and inland communities” ~ byWorld Weather Attribution
➥ https://www.worldweatherattribution....d-communities/

[2] “Yet another hurricane [Milton] wetter, windier and more destructive because of climate change” ~ byWorld Weather Attribution
➥ https://www.worldweatherattribution....limate-change/

[3] “Global Warming and Hurricanes” ~ by Tom Knutson, Senior Scientist, NOAA/GFDL
An Overview of Current Research Results
➥ https://www.gfdl.noaa.gov/global-war...nd-hurricanes/

All of the above, speaks to the relevance, to Cruisers, of the previous post #674