Skip to main content

The Art and Science of Forecasting

On a recent Friday afternoon I received an email sent to a group of people that suggested going to a DC United game the following Saturday. The emailer wrote "weather looks like it's going to be great!" with a link to a 10-day forecast showing sun and mild temperatures with a 20% chance of rain. 8 days went by and the weather on that Saturday turned out to be less great than anticipated.

(from Jorge Quinteros on Flickr)

I'm really glad Greg Postel published this post over at Capitol Weather Gang about the accuracy of advanced forecasting. It's worth a read, but if you're not going to click through, the short-version of is that Greg uses empirical data and shows  that forecasting accuracy decreases the farther you get from the actual date in question. It's not a surprising finding, but one that's worth re-enforcing.

Capitol Weather Gang is the best weather source around. The reason it's so great is because they not only give a forecast, but explain why they think it's going to happen, what the alternatives might be, and how confident they are in the forecast. I've never seen TV forecasters go into this level of detail. I've certainly never seen it in a generic 10-day forecast.

From what I understand, weather forecasting is a specialized skill. It's not something that an untrained person can really do especially well. I'm confident that this is the reason most people misinterpret weather forecasts.

For example, what does it mean if a forecast says 30% chance of rain? Does it mean that 3 out of 10 days this forecast appears it will rain? Does it mean that 30% of the coverage area will see some rain? Does it mean that it will rain for 30% of the day? Further, how much rain is going to occur? If it rains lightly for 5 minutes and is sunny the rest of the time, does that satisfy the condition? How does this apply to percentages given in the hour-by-hour forecasts?

These are all questions that a trained meteorologist could answer but that a lay person probably could not. Still, people often look-up a forecast up to 10 days in advance and state with confidence that it's going to be correct. That's probably a mistake.

Since I bicycle a lot, weather is more important to my daily life than it is to someone who doesn't bike very much. The only thing I've found to be truly reliable is the radar. When I wake up in the morning, I check the radar, if it looks like I'm in the clear for the next hour, I ride to work. I do the same thing in the evening. A forecast could show 90% chance of rain in a given day and I might be perfectly fine to bike to and from work without getting at all wet.


Popular posts from this blog

In Praise of Southwest's 'C' Boarding Group

A few weeks ago I saw a tweet from someone complaining that their Southwest Airlines boarding pass had been assigned A20 (meaning they would be at least one of the first twenty passengers to board the plane). Apparently this person though they should have been assigned a higher number, less their flight experience be considerably spoiled.

Despite the complaints, Southwest has resisted demands to assign seats on its flights, a decision which I personally applaud. I'll admit that I was skeptical when they rolled out the newest boarding procedure, assigning both boarding groups and a line number; but in hindsight it seems like one of the best operational decisions they've ever made. If nothing else, it effectively eliminated the infamous "cattle call" whereby fliers were getting to airports hours in advance and sitting in line on the floor as if they were waiting for the midnight showing of the new Star Wars movie.

When I was an intern at Southwest Airlines last winter, I…

So You Want to be a Southwest Airlines Intern?

My personal website must have pretty decent SEO - because in the past year, I've received about two dozen emails from aspiring Southwest Airlines interns looking to draw on my experience in search of their own dream internship. In the past two weeks alone a few new emails have already started rolling in...

(from flickr user San Diego Shooter)

If you've found your way here, you might be hoping for the silver bullet; a secret tip that will propel you above the competition. Unfortunately, I do not know any inside secrets. I can only share my experience as an internship candidate about two years ago and, rather than responding individually to future emails I anticipate to receive, I hope that potential interns will find the information posted here valuable.

Understand: Southwest Airlines is a very unique company. The corporate culture at Southwest is truly unlike that of nearly every other company. But you probably already knew that, since it now seems mandatory for every management,…

Mixing Sports and Business

In the last two days I've devoured every article in the Washington Post about the Nationals painful and epic defeat on Friday night in the NLDS. It was a tough way to see the season end, there's no doubt about that.

(from wallyg on Flickr)
These articles make it clear that there are a lot of people emotionally invested in professional sports. I think they sometimes they forget that, ultimately, Major League Baseball is big business. Each team is a major corporation and the league itself is an organization governed by a bunch of executives. The television networks that show the games are under contract with the team owners and the games aren't usually available to those without cable.

This is why it can be so hard to be a fan in this game. It's the multi-millionaire and billionaire owners that call most of the shots. They get to decide how much they're willing to spend on players. They get to decide who to hire as the CEO of the company. They get to decide how much t…