We predicted a fabulous 10 out of 10 day in D.C. Then it hailed.

Numerous showers and even some thunderstorms erupted during the afternoon — several unloading pea-sized chunks of ice. Some locations dodged the deluge and our 10 out of 10 rating was verified. But other places were blasted by the sudden cloud bursts, repeatedly.

Falls Church was one such place. Red blobs on the radar swept over the Virginia suburb in rapid succession. Lincolnia and Alexandria were also hit.

“I was promised 10/10. I’d like a refund please,” tweeted Capital Weather Gang follower @MikeHercz.

The National Weather Service had also predicted a precipitation-free afternoon.

So how did we get it so wrong?

Despite the fact a front had cleared the area 24 hours earlier, a disturbance packed with cold air at high altitudes zipped overhead. We didn’t think it would produce rain because the air was very dry near the ground.

But as the sun heated the ground and the warm air at low elevations ascended and contrasted with the chilly air aloft, clouds bubbled up. The disturbance was vigorous enough for tall, precipitating-producing clouds to mature.

And so it rained and hailed. Thursday marked the eighth day in a row with at least a trace of rain in Washington.

There were some computer models that showed a 10 percent chance of rain. That means in 9 out of 10 cases, it would have stayed dry in similar circumstances.

A better forecast would’ve called for increasing afternoon clouds and a slight chance of a shower or storm. The day’s rating probably should’ve been an 8 or so, rather than a 10.

What are the takeaways here?

1) We should include a chance of a shower in our forecasts when there’s strong sunshine and an intense high-altitude disturbance passing by.

2) Weather forecasting is humbling.