This is a day late, but yesterday was a busy one with lots of errands, which we capped with a viewing of “Thor: The Dark World.” (Short review: Fun if you turn off your brain — not that you should even bring your brain to a movie like this — and more enjoyable than the first Thor. We laughed quite a bit, oohed at the overall spectacle, and totally loved that the Convergence of the Nine Realms takes place directly over Greenwich. Because where else would it be? However, no amount of brain suppression will enable me to believe Natalie Portman as an astrophysicist. Sorry, but no.)
Given the almost unbelievable images of destruction now coming out of the Philippines, and Tacloban City specifically, today’s wallpaper had to be this one:
(Copyright 2013 JMA/EUMETSAT)
It’s a composite image, using NASA’s “Black Marble” image as a base, and overlaying satellite data from both the Japanese and the European meteorological agencies. From space, Super Typhoon Haiyan looks serene and beautiful — and also gigantic.
The mainstream media is making a lot of noise about how strong this typhoon was, but seems oddly unaware of how that claim was actually made. There is real data backing it up.
First, a little explanation:
In the Atlantic and the Gulf of Mexico, the National Oceanic and Atmospheric Administration (NOAA) sends planes into tropical storms and hurricanes to measure wind speed and barometric pressure. These measurements become the basis of the Saffir-Simpson classification system, which rates storms on a scale of 1–5.
In the Pacific, there is no equivalent agency with the resources to fling aircraft and scientists into these storms (which are called typhoons in this ocean, but hurricanes one ocean over. In case you ever wondered, yes, they’re exactly the same thing). So the data must be collected in a different manner — namely, by weather satellites. Since these data are a product of observation and estimation, rather than on-site measurements (you can learn the specifics here), a different rating scale is used. It’s called the Dvorak scale, and rates storms from 1–8. You can see what those numbers translate to in wind speeds and pressures in this NOAA chart, which also provides the Saffir-Simpson numbers for comparison.
Dvorak ratings are not cast in stone until they are confirmed (or altered) by real-time data measurements in the storm itself. Thus, the final Dvorak rating of Super Typhoon Haiyan is still waiting for data to come in from the areas that were in the storm’s path. Given how utterly destroyed many of those areas are, we may never be able to confirm Haiyan’s true strength.
With that in mind, here is why so many stories about Haiyan are saying it was the strongest storm to make landfall in recorded history. On the Dvorak scale of 1–8, Haiyan was so ferocious that it reached a rating of 8.1. It broke the scale.
Given the strength of this typhoon, the storm surge was bound to be high. And it was, estimated to reach 5.2 meters (17 feet) in Leyte, where Haiyan first came ashore. At water levels like this, there’s little difference between a storm surge and a tsunami. The waters rise rapidly and push inland to distances of a kilometer or more, with such force that humans have little hope of withstanding it.
Haiyan’s sustained 315 kph winds (195 mph) were bad enough, but it was the storm surge that seems to have caused most of the fatalities. Filipinos are used to typhoons, since their nation gets hammered on a regular basis. Thus, many people in the coastal areas either did not evacuate, or only partially evacuated, leaving someone behind to guard the property and prevent looting. The storm surge took them by surprise, in some places flooding both the first and the second floors of homes and buildings. It is likely that the death toll will never be known, with many bodies being swept out to sea.
They were expecting a big typhoon. They just weren’t expecting one of the biggest, if not the biggest, in recorded history.
(Click the image to embiggen. For more photos of Super Typhoon Haiyan’s impact on the Philippines, go to The Atlantic’s In Focus.)