Double Your Hurricanes, Double Your Fun

In a first, the Gulf of Mexico basin has two active hurricanes simultaneously. Unfortunately, they are both likely to strikes somewhere along the Louisiana coastline within approximately 36 hours of each other. Fortunately, neither is strong as a storm named Katrina that caused a mess of things several years ago now.

Over the last few weeks I have been trying to start the week with my Covid datagraphics, but I figured we could skip those today and instead run with this piece from the Washington Post. It tracks the forecast path and forecast impact of tropical storm force winds for both storms.

The forecast path above is straight forward. The dotted line represents the forecast path. The coloured area represents the probability of that area receiving tropical storm force winds. Unsurprisingly the present locations of both storms have the greatest possibilities.

Now compare that to the standard National Weather Service graphic, below. They produce one per storm and I cannot find one of the combined threat. So I chose Laura, the one likely to strike mid-week and not the one likely to strike later today.

The first and most notable difference here is the use of colour. The ocean here is represented in blue compared to the colourless water of the Post version. The colour draws attention to the bodies of water, when the attention should be more focused on the forecast path of the storm. But, since there needs to be a clear delineation between land and water, the Post uses a light grey to ground the user in the map (pun intended).

The biggest difference is what the coloured forecast areas mean. In the Post’s versions, it is the probability of tropical force winds. But, in the National Weather Service version, the white area actually is the “cone”, or the envelope or range of potential forecast paths. The Post shows one forecast path, but the NWS shows the full range and so for Laura that means really anywhere from central Louisiana to eastern Texas. A storm that impacts eastern Texas, for example, could have tropical storm force winds far from the centre and into the Galveston area.

Of course every year the discussion is about how people misinterpret the NWS version as the cone of impact, when that is so clearly not the case. But then we see the Post version and it might reinforce that misconception. Though, it’s also not the Post’s responsibility to make the NWS graphic clearer. The Post clearly prioritised displaying a single forecast track instead of a range along with the areas of probabilities for tropical storm force winds.

I would personally prefer a hybrid sort of approach.

But I also wanted to touch briefly on a separate graphic in the Post version, the forecast arrival times.

This projects when tropical storm force winds will begin to impact particular areas. Notably, the areas of probability of tropical storm force winds does not change. Instead the dotted line projections for the paths of the storms are replaced by lines relatively perpendicular to those paths. These lines show when the tropical storm winds are forecast to begin. It’s also another updated design of the National Weather Service offering below.

Again, we only see one storm per graphic here and this is only for Laura, not Marco. But this also probably most analogous to what we see in the Post version. Here, the black outline represents the light pink area on the Post map, the area with at least a 5% forecast to receive tropical storm force winds. The NWS version, however, does not provide any further forecast probabilities.

The Post’s version is also design improved, as the blue, while not as dark the heavy black lines, still draws unnecessary attention to itself. Would even a very pale blue be an improvement? Almost certainly.

In one sense, I prefer the Post’s version. It’s more direct, and the information presented is more clearly presented. But, I find it severely lack in one key detail: the forecast cone. Even yesterday, the forecast cone had Laura moving in a range both north and south of the island of Cuba from its position west of Puerto Rico. 24 hours later, we now know it’s on the southern track and that has massive impact on future forecast tracks.

Being east of west of landfall can mean dramatically different impacts in terms of winds, storm surge, and rainfall. And the Post’s version, while clear about one forecast track, obscures the very real possibilities the range of impacts can shift dramatically in just the course of one day.

I think the Post does a better job of the tropical storm force wind forecast probabilities. In an ideal world, they would take that approach to the forecast paths. Maybe not showing the full spaghetti-like approach of all the storm models, but a percentage likelihood of the storm taking one particular track over another.

Credit for the Post pieces goes to the Washington Post graphics department.

Credit for the National Weather Service graphics goes to the National Weather Service.

The Map

I mean come on, guys, did you really expect me to not touch this one?

Well we made it to Friday, and naturally in the not so serious we have to cover the sharpie map. Because, if the data does not agree with your opinions, clearly the correct response is to just make shit up.

By now you have probably all heard the story about how President Trump tweeted an incorrect forecast about the path of Hurricane Dorian, warning how Alabama could be “hit (much) harder than anticipated”. Except that the forecast at the time was that Alabama wasn’t going to be hit. Cue this map, days later. As in days. As in this news story continued for days.

Note the sharpie weirdly extending the cone (in black, not the usual white) into Florida and onward into Alabama.
Note the sharpie weirdly extending the cone (in black, not the usual white) into Florida and onward into Alabama.

So to be fair, I went to the NOAA website and pulled down from their archive the cone maps from the date of the graphic Trump edited, and the one from the day when he tweeted about Alabama being hit by the hurricane.

Important to note that this forecast dates from 29 August. This press conference was on 4 September. He tweeted on 1 September. So in other words, two days after he used the wrong forecast, he had printed a big version of a contemporaneously two-day old forecast to show that if he drew a sharpie line on it, it would be correct.

Here is the original, from the National Hurricane Centre, for 29 August. Note, no Alabama.

No Alabama in this forecast, the OG, if you will (and if I'm using that term correctly).
No Alabama in this forecast, the OG, if you will (and if I’m using that term correctly).

And then Trump tweeted on 1 September. So let’s take the 02.00 Eastern time 1 September forecast from NOAA.

By 30 August the forecast was already tracking northward, not westward. So by 1 September the idea that the hurricane would hit Alabama was just nonsense.
By 30 August the forecast was already tracking northward, not westward. So by 1 September the idea that the hurricane would hit Alabama was just nonsense.

Definitely no Alabama in that forecast.

This could have all gone away if he had just admitted he looked at the wrong forecast and tweeted an incorrect warning. Instead, we had the White House pressuring NOAA to “fix” their tweet.

Now we can all chalk  this up as funny. But it does have some serious consequences. Instead of people in the actual path of Dorian preparing, because of the falsely wide range of impacts the president suggested, people in Alabama needlessly prepared for a nonevent.

But more widely, as someone who works with data on a daily basis, we need to agree that data is real. We cannot simply change the data because it does not fit the story we want to tell. If I could take a screenshot of every forecast and string them together in an animated clip, you would see there was never any forecast like the sharpie forecast. We cannot simply create our own realities and choose to live within them, because that means we have no common basis on which to disagree policy decisions that will have real world impacts.

Credit for the photo goes to Evan Vucci of the AP.

Credit for the National Hurricane Centre maps goes to its graphic team.

We’re All Just Palm Trees and Patio Furniture in the Wind

For all my American readers, I hope you all enjoyed their Labour Day holiday. For the rest of you, today is just a Tuesday. Unless you live in the Bahamas, then today is just another nightmarish day as Hurricane Dorian continues his assault on the islands.

The storm will be one for the record books when all is said and done, and not just because of the damage likely to be catastrophic when people can finally emerge and examine what remains. The storm, by several metrics, is one of the most powerful in the Atlantic since we started recording data on hurricanes. If we look at pressure and sustained wind speeds, i.e. not wind gusts, Sam Lillo has plotted the path of Dorian through those metrics and found it sitting scarily in the lower-right corner of this plot.

How low can it go? Probably not much, thankfully.
How low can it go? Probably not much, thankfully.

The graphic does a couple of nice things here. I like the use of colour to indicate the total number of observations in that area. Clearly, we see a lot more of the weaker, higher pressure storms. Hence the dark blue in the upper-left. But then against that we have the star of the graphic, and my favourite part of the plot: the plot over time of Dorian’s progress and intensification as a storm. The final green dot indicates the point of the last observation when the graphic was made.

Overall this is a simple and solid piece that shows in the available historical context just how powerful Dorian is. Unfortunately that correlates with likely heavy damage to the Bahamas.

Credit for the piece I presume goes to Sam Lillo, though with the Twitter one can never be entirely certain.

New Orleans Dodges a Bullet

Hurricane/tropical storm Barry has been dumping rain along the Gulf Coast for a few days now. But prior to this weekend, the biggest concern had been for the city of New Orleans, which sits besides the swollen Mississippi River. The river was running already high at 17 feet above normal, and with storm surges and tropical rain levels forecast, planners were concerned not with the integrity of the city’s levee system, rebuilt in the aftermath of Hurricane Katrina, but simply whether they would be tall enough.

So far, they have been.

The Washington Post tracked Barry’s course with the usual graphics showing forecast rainfall amounts and projected tracks. However, the real stunner for me was this cross section illustration of New Orleans that shows just how much of the central city sits below sea level. The cross section sits above a map of the city that shows elevation above/below sea level as well as key flood prevention infrastructure, i.e. levees and pumping stations.

A lot floodable space
A lot floodable space

The unmentioned elephant remains however. The National Oceanic and Atmosphere Administration’s extreme climate change impact forecast says the water around New Orleans might rise by nearly 13 feet by 2100. Clearly, that is still well below the 20 feet levees of today. But what if there were to be a 17 feet high Mississippi River atop the additional 13 feet? 30 feet would flood the city.

Credit for the piece goes to John Muyskens, Armand Emamdjomeh, Aaron Steckelberg, Lauren Tierney, and Laris Karklis.

First Florence, Now Michael

You may recall a few weeks ago there was a hurricane named Florence that slammed into the Carolina before stalling and dumping voluminous amounts of rain that inundated inland communities in addition to the damage by the storm surge in the coastal communities. At the time I wrote about a New York Times piece that explored housing density in coastal areas, specifically around the Florence impact area.

Well today the New York Times has a print graphic about something similar. It uses the same colours and styles, but swaps in a different data set and then uses a small multiple setup to include the Florida Panhandle. Of course the Florida Panhandle was just struck by Hurricane Michael, a Category 4 storm when it made landfall.

Of course that track for Michael also brought significant rainfall to the areas recovering from Florence for a double whammy
Of course that track for Michael also brought significant rainfall to the areas recovering from Florence for a double whammy

This one instead looks at median income per zip code to highlight the disparity between those living directly on the coast and those inland. In these two most recent landfall areas, the reader can clearly see that the zip codes along the coast have far greater incomes and, by proxy, wealth than those just a few zip codes further inland.

The problem is that rebuilding lives, communities, and infrastructure not only takes time, but also money. And with lower incomes, some of the hardest hit areas over the past several weeks could have a very difficult time recovering.

Regardless, the recoveries on the continental mainlands of the Carolinas and Florida will likely be far quicker and more comprehensive than they have been thus far for Puerto Rico.

The only downside with this graphic is the registration shift, which is why the graphic appears fuzzy as colours are ever so slightly offset whereas the single ink black text in the upper right looks clear and crisp.

Credit for the piece goes to the New York Times graphics department.

All the Crazy Models

Over the last several weeks we dealt with the impact of a few hurricanes from H to K, i.e. Harvey, Irma, Jose, and Katia. Now that the Atlantic basin has quieted a wee bit, it is time we get back to the lighter side of things.

So we turn to xkcd and its look at ensemble models, often used to try and predict the paths of hurricanes.

I like to swap the victor of the colonial revolt in North America ca. 1776…
I like to swap the victor of the colonial revolt in North America ca. 1776…

Happy Friday, everyone.

Credit for the piece goes to Randall Munroe.

How Big Was Irma?

Like many Americans I followed the story of Hurricane Irma over the weekend. One of my favourite pieces of reporting was this article from the Washington Post. It did a really nice job of visually comparing Irma to some recent and more historic storms, such as 1992’s Hurricane Andrew.

It can be difficult to truly compare hurricanes, sometimes they are small and compact, other times more dispersed. Irma was just big with lots of potentially destructive power spread out across a wide area, almost the width of the Floridian peninsula. The article uses several graphics—I am also quite partial to the satellite image comparison so check out the article—but this one is perhaps my favourite.

A look at four big storms
A look at four big storms

It uses a colour palette that deepens in redness nearer the storm’s centre. This allows the user to compare the geographic area or footprint of the storms destructive winds.

I wonder, however, what would happen if the designers had superimposed each graphic atop the other. It might have allowed for an even better comparison of size instead of having to have the user mentally transpose each hurricane.

Still, a really nice graphic and visual article.

Credit for the piece goes to Bonnie Berkowitz, Laris Karklis, Reuben Fischer-Baum, and Chiqui Esteban.

Irma’s Impending Arrival

Your author is on holiday today and is actually writing today’s post on a Thursday night train to Boston. But by the time he returns late Sunday night—a Monday morning post is not guaranteed—Hurricane Irma will have likely made landfall somewhere along the Florida coast.

Thursday the Guardian published a nice article looking at the potential tracks for Irma. And while the specific routes will certainly be amended and updated over the weekend, the article is worth looking at prior to Irma’s arrival at Florida. As of my writing the track has shifted ever slightly westward and the current predicted path looks for Irma to land south and west of Miami. Ergo this screenshot is already a little outdated.

The three little wolves will huff and puff…
The three little wolves will huff and puff…

The remarkable thing about this graphic, which is just a cleaner version of the standard meteorological maps through more a more considered palette, is that there is not just one path of winds, but three. Following quickly on the heels of Irma are Katia and Jose, the latter the one taking the nearly same path as Irma while Katia spins towards Mexico.

But the graphic I really wanted to look at is the one ending the piece.

A very wide range of countries
A very wide range of countries

This looks at the countries in Irma’s path as of Thursday morning. What I do not understand is the vertical axis of the bars. What does the height represent? To simply show the rank of countries able to cope with natural disasters, a more straight-forward table could have been used. A dot plot would also make some sense, but again, it would require an understanding of the underlying metrics driving the chart.

The graphic is saved by the annotations, in particular the more/less vulnerable directional arrows. Because I do not understand why countries are grouped into the particular buckets, I find the coloured bins out of place.

I think the concept of showing the most vulnerable countries is terribly important, however, the graphic itself needed a little more thought to be a little more clear in presenting the concept.

Credit for the piece goes to the Guardian graphics department.

Hurricane Winds

Irma swept the northern coast of Puerto Rico last night after devastating some of the Leeward Islands. What’s next? Well after the Turks and Caicos, Cuba, and the Bahamas we are probably looking at a Florida landfall. (Though in the last 24 hours the track has shifted ever eastward so Tampa Bay looks fine from a direct impact standpoint.)

Harvey was an exception in many ways because most deaths occur not from rainfall flooding, but from the storm surge. Basically a massive wave of water driven by low pressure and strong winds that is literally pushed ashore.

Now even though I just said that, I wanted to talk about the winds for a second. Why? Well it turns out that at 185mph, Irma has some of the strongest sustained winds ever recorded for an Atlantic hurricane. And 185mph winds, they can do quite a bit of damage. How much? Well for that we turn to this illustration from Vox.

You do not want to be around for a Category 5
You do not want to be around for a Category 5

Assuming the worst case scenario and Irma would strike just southwest of Miami, say Homestead or Key Largo, 185mph winds could do some damage to non-hurricane-safe buildings in a very large American city. And then there is the storm surge, which could be problematic for a city that is already struggling with rising tides. (Thanks, climate change.) The reason I say worst case is southwest of Miami is because hurricanes do most of the their damage—though certainly far from all of it—on their righthand side, which in a northward moving storm would be the eastern half.

The rest of the Vox piece does a nice job explaining Irma, its historic nature, and how it could be so dangerous. Worth a quick read, unless you live in Florida and then you should probably be packing up to evacuate.

Credit for the piece goes to Zachary Crockett.

Tampa Bay and Hurricanes Do Not Mix

About a year ago Pro Publica and the Texas Tribune published a piece that documented the calamity of a hurricane striking and flooding the city of Houston. It proved rather prescient a week or so ago.

So a little over a month ago the Washington Post published an article about the catastrophe that could await Tampa Bay if a major hurricane were to strike the area. I read it, enjoyed it, and found it informative, but opted not to share it with all of you.

Well now we have Hurricane Irma barrelling towards Florida after it struck the Leeward Islands this morning. So today felt like a decent day to share the story.

Not looking so great
Not looking so great

Credit for the piece goes to Darryl Fears, Zoeann Murphy, Kolin Pope, Denise Lu, and Danielle Rindler.