The Weather Channel’s forecast as of early Wednesday, when Democrats announced their decision, called for a 30 percent chance of rain on Thursday night. (The forecast has since been revised to a 40 percent chance of rain.)
But is a 30 percent chance of rain really all that far out of the ordinary? Rain is hardly unknown in the South — especially in the humid evenings of the late summer.
Perhaps Democrats are using the weather threat as an excuse to protect against the possibility that they couldn’t fill a football stadium? Or perhaps they liked how Michelle Obama’s speech came across indoors at the Time Warner Cable Arena, preferring its intimacy to an outdoor stadium’s grandiosity?
In order to put their weather claim into context, I looked up the historical weather reports for Charlotte in September at Wunderground.com, going back 10 years.
Specifically, I looked at how often there had been rain or thunderstorms between 8 p.m. and 11 p.m. local time — the key hours for the speeches, and the logistics for getting everyone safely into the stadium.
In the Septembers since 2002, it has rained 13 percent of the time during these prime-time hours in Charlotte. Thunderstorms, however, are relatively rare during these hours, occurring just 3 percent of the time.
The Weather Channel did not provide a precise estimate of the chance of thunderstorms specifically, as opposed to any kind of rain. But if we infer that the chance of thunderstorms is 15 percent on Thursday night — half the chance of there being any type of precipitation — it is considerably greater than Charlotte’s long-term average.
Still, the threat of thunderstorms hasn’t stopped the Democrats before. Denver, where Mr. Obama made an outdoor address at the convention in August 2008, is a city prone to storms.
Thunderstorms are a little different in Denver. They tend to formulate quickly over the turbulent air of the Front Range, but also pass through the town quickly rather than linger. Fairly often in Denver, in fact, there is thunder and lightning that is not accompanied by rainfall.
Nevertheless, scheduling an outdoor speech in Denver is not something you do if you are extremely skittish about a severe weather event and its impact on optics, logistics and security.
Obviously, this is a close call — both in terms of the decision by the Democrats, and in interpreting their motivation for it. But some skepticism is warranted that the weather is the only thing they were thinking about.