How much do we really know about hurricanes?

[xmetman]

Hurricane Matthew – courtesy of Reuters and the Boston Globe.

I noticed an article in the September 2016 Weather magazine from the Royal Meteorological Society entitled “Understanding hurricanes” by Roger K. Smith and Michael T. Montgomery. It was very informative and it starts:

“Hurricanes are among the most fascinating of all atmospheric phenomena. Much of their intricate dynamics and thermodynamics can be explained within the realm of classical physics. However, some of their secrets are yet to be unlocked.”

I like the phrase “some of their secrets are yet to be unlocked“, secrets like how much will they intensify and where are they going next. It’s exemplified by the two tropical cyclones hurricane Matthew and tropical storm Nicole that are currently cruising the waters off the eastern seaboard of the United States.  I’ve been reading the forecast discussion on each storm from the National Hurricane Centre [NHC] avidly as I have done for many years. I noticed that in past years many would be hurricanes never made it because of upper wind shear that stopped any further intensification and the storm ended up as a post tropical cyclone to be absorbed by a trough, or even a worst indignity of being gobbled up by an extratropical low. But this season has been a little odd.

I now notice that despite early forecasts of Nicole fizzling out due to unfavourable conditions, it looks quite likely that Nicole will reach at least category one hurricane status later today, not bad for a storm that should now be a subtropical depression or remnant low.

So what is going on this season in the Atlantic basin? Tropical storms seem to be doing what they want, totally ignoring the rules laid down in classical physics about tropical cyclone development. Despite all the satellite imagery and sophisticated NWP models we don’t seem to have that firm a grasp about why cyclones rapidly intensify as Matthew has done. Forecasting the track of a tropical cyclone, although good with Matthew and Nicole up to now, is far from perfect, and I’m sure that you’ll remember the “left hook” that hurricane Sandy gave to New York in 2012. 

But thanks to George Bernard Shaw there is one thing I do know about hurricanes, and that is that in Hertford, Hereford and Hampshire hurricanes hardly ever happen!

[MartinR]

Does a hurricane over shallow water (such as the Bahamas, Florida Keys and barrier islands stand a better chance of intensifying due to lack of cold water being churned up from the depths?

MartinR

[xmetman]

Interesting point but I bet the models probably just require a simple SST value which is not adjusted for the surface layer being agitated - but that's only my guess.

[Alastair B. McDonald]

I was surprised that they were saying Matthew was going to lessen as it went north. The route seemed to follow the warm Gulf  Stream. I note that it is intensifying now.

[Richard Dixon]

On Thursday, 6 October 2016 19:41:37 UTC+1, Alastair B. McDonald wrote:

I was surprised that they were saying Matthew was going to lessen as it went north. The route seemed to follow the warm Gulf  Stream. I note that it is intensifying now.

The high resolution models aren't weakening it (the HWRF isn't at least). The interaction with land as it scrape along the post will likely weaken it by dint of part of the structure of the storm being over land and not over warm sea.

This has the potential to be quite an event given that it's not your typical hurricane that makes landfall perpendicular to the coast and fizzles quickly inland. Many kilometres of the coastline are in the firing line as it drags along the coast. A great test of Florida's building codes that went under review in 2005 after the 2004 hurricane season.

Richard

[Stephen Davenport]

Matthew has concentric eyewalls and looks like a textbook mature hurricane per Houze (2010).

(h/t Anthony Sagliani).

By the way, given that it has killed at least 136 people at time of writing, I wouldn't say that Matthew has been "hyped"! 

Stephen

Indianapolis IN

[xmetman]

Stephen

Yes, you're quite right I over stepped the mark with the hyped bit, but I'm afraid all the warnings in the world wouldn't have stopped the deaths of these people. The poor are always the going to be the first casualties when a hurricane strikes in situations like this, dying trying to protect what few possessions they have rather than fleeing. It's just a shame that the situation in Aleppo doesn't get the attention that Hurricane Matthew has received in the last week, but that's a reflection of how crazy our world is when viewed on the internet or on our TV screens. One unnecessary death anywhere for whatever reason is one death too many.

Bruce.

[Stephen Davenport]

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Aye, it's a tragedy in places like Haiti. It's just as you say; plus there just isn't the warning dissemination system in place, the infrastructure to move so many people or the means for many of those people to move out even if they wanted to. Over 400 fatalities now.   

In Florida it looks not as bad as it could have been at the moment with the eye about 10 miles farther east - but the eye-wall just scraping the coast. Tiny margins can make quite a difference, and these three small wobbles helped:

Of course, remaining parallel with the coast will likely mean (although weakening a little) keeping a little more strength than otherwise farther north off the coast of Georgia / S Carolina.

Of slight interest, here is absence of flights over eastern Florida this morning - except for the one circled which is a NASA plane.

Agreed about Aleppo. It's indescribably awful.

Stephen. 

[Steve Jackson]

I see the death toll in Haiti is now over 800; this is a tragic loss of life, but so avoidable in the 20th century surely?

Hurricanes travel slowly enough to predict within a few days' timeframe, just where landfall will be, give or take a hundred miles or so.

Governments, including Haiti's, issue evacuation warnings for those living near the coast, so just as in New Orleans with Katrina, the majority of those killed chose to ignore warnings and stay at home in abuilding that is totally inadequate to survive landslides, storm surge and strong winds - all forecast well in advance. Surely all the people have to do is climb a hill and sit it out in a field? They would be wet windswept frightened but alive as the hurricane passes; huddled together, they would survive to live another day, even if looters threatened their possessions.

To make matters worse, today I read on Twitter that this horrific loss of life  has been dubbed "environmental racism" with a hashtag #blacklivesmatter ! Surely all lives matter in a natural disaster?

Just a few thoughts on an eminently avoidable disaster!

Steve J

[Richard Dixon]

On Friday, 7 October 2016 19:20:42 UTC+1, Steve Jackson wrote:

give or take a hundred miles or so.

It's a matter of 50 miles or so (or less) that has spared the E Coast of Florida the strongest of winds but damage that is emerging right at the coast seems commensurate with peak gusts of 80-90 mph.

Forecasts in the last 2 days or so have been excellent in terms of track - Matthew looked like it was always going to flirt with the coastline after the models made their westward shift on Tue/Wed. It's almost hugged the coastline at times and does make me wonder whether there is some form of land/sea roughness gradient mesoscale effect on the hurricane, although this could be folly.

The one remaining concern for me is the surge as it moves north into the bend into Georgia and maybe Charleston. The bathymetry further south in Florida is less conducive to surge and as the forecasts have well suggested, the higher surge values are likely further north not too dissimilar to those seen in Sandy.

Richard

[Stephen Davenport]

On Friday, October 7, 2016 at 2:20:42 PM UTC-4, Steve Jackson wrote:

 

Surely all the people have to do is climb a hill and sit it out in a field? They would be wet windswept frightened but alive as the hurricane passes; huddled together, they would survive to live another day, even if looters threatened their possessions.

========

I don't think that hunkering down in a field on a hill during a Cat 4-5 hurricane is necessarily survivable.

Stephen. 

[Steve Jackson]

So what would kill people in a field in a hurricane Stephen?

Not pleasant for sure, but surely survivable in a group huddle with blankets?

Wouldn't want to go through it myself, but better than staying put in ramshackle housing with flying debris and a storm surge surely?

Just asking!

It was the 'environmental racism bit that really concerned me however! So we in the white west are responsible are we? #alllivesmatter IMHO

Steve J

[Stephen Davenport]

=========

What would kill people up a hill in a field? You mentioned "landslides" yourself. And although you wouldn't be directly in danger from flooding or a collapsing building, why would a field necessarily be free from flying debris in 100mph+ winds? Even if you could find a field in Haiti far from trees. Furthermore, a soaking blanket is not going to be sufficient to shield you from risks of hypothermia. 

Let's not get diverted off topic down the path of those hashtags. Personally the bit that really concerns me is more than 800 dead people.

Stephen.

Indianapolis IN  

 

[Graham Easterling]

I can't imagine it being possible to walk across a field in a category 4 hurricane.

 I've been out in a F9 (possibly 10) on a few occasions to get pictures like this http://www.turnstone-cottage.co.uk/StormImogen2016.pdf  F8 by the harbour, more on the cliff top, where you had to cling on to have any hope of staying stay upright. I doubt if I'd have made it across the clifftop car park, it would certainly be impossible in a F10-11. Even in that basically tree free landscape there was plenty of debris flying. I felt very cold, wet & battered after a few minutes.

I think the media use of 'gale force gusts' & 'hurricane force gusts' have devalued the real terms to the point where the real thing can be grossly underestimated.

Graham

Penzance