Hurricane Florence has strengthened as expected. There will likely be some more strengthening, followed by some weakening near the coast. Florence will remain a major and deadly hurricane until after landfall, and then, it will be a deadly flood causing storm with significant winds.
Timing
The best estimate for timing of events is as follows.
On Wednesday morning, Hurricane Florence will likely be looming just off the Carolina coast, with winds of about 140 mph (making it a Category 4 Hurricane).
Tropical storm strength winds will come ashore Wednesday night. Strong surf will have already developed.
The strongest part of Florence will be pounding the Carolina coast at sunup on Friday, and the storm may sit right on the coast for several hours as it winds down to a tropical storm. Landfall and this rapid weakening may happen at about the same time. It is remotely possible that the eye wall will not pass over the coast, thus causing weather reporters and climate disaster deniers to become stupified.
Storm surge
It is important to understand how storm surge warnings work. There are two kinds of estimates that can be made. One is to assume exactly where the eye will come ashore, exactly when (to include the contribution of tieds), estimate the wind speed and forward speed of the storm, and the angle of movement, then use all these variable together with the topography of the coast to estimate how high flooding will be at any given point.
The second is to look at where the storm may go, and how strong it might be, and how those other variables will pan out, but with uncertainty in location and timing being much larger, and produce a map of coastal regions indicating where there might be high flooding, and how high that might be.
The former is generally not what you are looking at when you see a storm surge map. For example, right now there are estimated storm surges of over 9 feet near Kinston and Greenfille North Carolina, but only one foot in and around Albermarle sound. This is based on a combination of the likely track and behavior of the storm but considering that we don’t know exactly where the storm is going to hit. The difference between Greenville and Albermarle sound is a combination of where we think the storm is going and what the storm might do. The two topographies are greatly different, accounting for most of the difference in possible flood height.
In other words, most of the flood levels indicated in most storm surge maps are not going to happen. Only some of them. But, we don’t know which ones.
Anyway, there are storm surges expected to be greater than 9 feet in some places. Even three foot surges are a lot if it is high tide along very low lying barrier islands. If Florence does plow into North Carolina as expected, it is quite likely that the configuration of the barrier islands along that coast will change. Some lines may become dotted lines. Some inlets may be filled, some new inlets created, many tidal channels in the estuaries will shift. Places like the town of Ocracoke may suffer very sever damage, as they lie below the maximum possible food surge.
Flooding
Aside from storm surge, flooding happens inland with hurricanes. The special feature of East Coast hurricanes, especially in “Hurricane Alley”, between Northern Georgia and southern Virginia, is that behind the coastal plain there is a mountain range. So, if tropical storm carried water dumps on that mountain range, a two or three inch rainfall over a very large area can cause significant flooding.
Rainfall of over four inches is expected to fall over most of Virginia, and about half of North Carolina. Delaware, DC, Delmarva, Maryland, southern Pennsylvania, and parts of West Virginia and South Carolina will also get lots of rain. The area of expected landfall, and a few areas in land (like in south-Central Virginia) may see rainfall totals of over 15 inches, maybe two feet right along the coast.
A lot of roads and bridges will be wiped out, immortal doods in large pickups will be obviated, and low lying villages will be flooded. Unless the storm does a zany (and very unlikely) turn to the north before coming ashore, this may be the biggest problem, since it is hard to evacuate five or six states.
Washington DC could get up to a foot of rain. Note: The White House lies on much lower terrain than the Capitol. I’m not promising you a Rose Garden flood, but it could happen.
What if
Florence is just like any other storm of the day: Enhanced by global warming. But note this. Florence will weaken from a strong Category 4 storm to a strong Category 3 storm as it gets near the coast. This will happen because the warm waters on the surface will be churned by the storm itself into the colder water at depth, weakening the storm. Over recent years, however, we’ve seen storms fail to weaken, or even strengthen when they would normally have weakened, because the deeper water is still at “hurricane-strength” temperature. Katrina, Haiyan, and some of last year’s Atlantic storms exhibited this behavior.
With increased warming of the sea, this will eventually start to happen in the US East Coast littoral. Florence ten or twenty years from now would build to Category 5 strength and keep that level of intensity, or nearly, before reaching the shore. And, in ten or twenty years from now, sea levels will be higher. And, by then, a few other hurricanes would have smashed up the barrier islands. In 20 years, North Carolina and Virginia are not likely to be very well protected by those sand features. James Hansen was right.
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I know it’s wrong of me to hope for it but if it does have to hit land then it would be much nicer if it moved to the North East and made landfall right on Washington DC as a CAT 5 with the the worst part hitting the WH directly. Mind you the evangelical preachers would just say it is Satan trying to wipe out The Donald by following the evil wishes of the alt-left or some similar crap.
James Hansen was indeed correct. In fact, he was and remains pretty much bang on the money for his estimations of response to particular emissions scenarios.
Those without expertise should have ceded to Hansen’s (and others’) decades ago.
My question is will we count the number of people killed by the storm itself, or do we just count everybody in the area who died during the storm and call that the death count?
Inquiring minds want to know.
What do you think Einstein?
You don’t have an inquiring mind. I’ll hand over to SteveP, who beat me to it:
We’ll count the number of people who died but would not have had the storm not caused them to die!
Thanks Greg:
That sounds exactly right to me.
I like a good “but for” test.
Hopefully the number will be zero or very low!
“Of course, many readers are going to say that now is not the right time to mix weather and politics — because hurricanes and wildfires are becoming the mass shootings of the climate-change debate, where saying anything in a moment of crisis beyond offering our thoughts and prayers to the afflicted is crass and inappropriate. But thoughts and prayers won’t help the mostly underprivileged residents of the low-lying Carolinas any more than they saved gunshot victims in Parkland. The reality is there’s no better time to talk about our failure to take climate politics seriously than on the eve of a natural disaster that global warming is making worse.”
http://www2.philly.com/philly/columnists/will_bunch/hurricane-florence-north-carolina-climate-change-politicians-20180911.html
Trump is preparing for Florence by boasting about his response to Maria:
“I actually think it’s one of the best jobs that’s ever been done.”
The coverage of an event that hits the American mainland will be far more intense and will subject the government’s response to far greater scrutiny. And the midterms are two months off.
“underprivileged residents”
I’m curious about these people, and how they live.
Images I have seen of the region suggest a very high standard of living so your statement is a bit confusing.
Looking at food prices converted to AUD.
https://www.numbeo.com/food-prices/in/Charleston?displayCurrency=AUD
Hmmmm Food is outrageously expensive. 8 bucks for a kilo of rice!!!
Someone’s making a lot of money out a rice in this place.
Still, if someone works for an hour they can get a kilo of it and feed their family for a couple meals so that’s pretty good.
This may turn out to be a really edifying moment regarding conservative principles in general. Conservative N.C. legislator Pat McElraft’s “ignore the sea level rise” bill paints the conservatives pretty close to the way they really are IMO; as money ruled pricks, willing to blind themselves and others to physical realities in order to make a buck. Pat Robertson has pulled out his Jesus the Wizard wand to ward off what the evil scientists predict could be a real disaster. If the storm does take a premature turn to sea, he can bill himself as the second coming, and if it crashes into NC as predicted, well, people will be too busy looking for their loved ones, the remnants of their possessions, and food, water, and shelter to remember his grandiosity. What if it stalls off shore, but the surge kills hundred? Will he take responsibility for stopping the storm? Fucking idiots.
BTW, belittling the deaths of 3,000 people is immature and inappropriate at best, sick and dehumanizing at worst. Rather than come across as a witty inquiring mind, RickA, you have come across as a stupid, needling, annoying, sociopathic, conservative prick. Conservatives have been raping Puerto Rico economically and psychologically since before the 1890’s, and RickA, you apparently felt compelled to join into the latest remnants of that cluster fuck. What a typical, heartless, brainless, conservative political pervert you are. You should seriously consider growing up and not doing your dehumanizing shit here any more. It will be better for you if you do.
What can I add to this that Steve hasn’t already elegantly captured?
+1.
It is interesting that you think accurate death attribution is belittling the deaths of 3000 people.
When I look at this graph I eyeball about 1300 excess deaths:
http://econbrowser.com/archives/2018/06/excess-deaths-inferred-from-puerto-rican-administrative-data
I wonder if incorrectly attributing 1700 deaths to a hurricane is belittling?
Oh well – you are certainly entitled to your opinion.
Remember, ricka is not only intentionally dishonest in everything he says and does, he’s incapable of understanding anything relating to science, mathematics, or statistics, so his habit of rejecting studies that have results he doesn’t like isn’t a flaw, it’s a feature central to his person
On the PR death rates. The figure referred to by RickA is from an earlier study, which was the first indication that the number of dead from that hurricane was not 64, but much larger, owing to destruction of infrastructure including hospital power sources, etc.
That was early August.
More recently, the Milken Institute of Public Health released its study, which uses different methodology that is arguably better, and the result of that study is a much higher rate, close to double of the earlier study.
I’m not sure if 64 being actually 1400 or actuall 3000 makes much difference when we look at Maria, Trump, FEMA, Puerto Rico, and climate change.
But, if anyone wants to look into it further, he’s the latest report:
https://prstudy.publichealth.gwu.edu/sites/prstudy.publichealth.gwu.edu/files/reports/Acertainment%20of%20the%20Estimated%20Excess%20Mortality%20from%20Hurricane%20Maria%20in%20Puerto%20Rico.pdf