Monday, November 24, 2014
Inquirer Daily News

Atmosphere's secrets safe

That AccuWeather 45-day outlook: How it's going.

Atmosphere's secrets safe

The weather community howled like the March wind when AccuWeather announced in August that it was issuing 45-day daily forecasts.

By our own scoring system, the first forecast we saw actually fared a tad better than we expected, with the caveat that our expectations were about as low as the December sun at 4 p.m.

And we can assure our readers that in any event, beyond 10 to 14 days the atmosphere’s secrets are still safe from AccuWeather, and everyone else as far as we know.

We looked at the first 40 days of the 45-day outlook starting with Aug. 8, and to summarize, the forecasts performed respectably the first two weeks, and then deteriorated.

First, an overview of  all 40 days: In terms of average temperature, AccuWeather was within 3 degrees Fahrenheit – which we considered a reasonable margin of error -- on half the days.

Granted we used a liberal grading system, but on only 12 of the days did AccuWeather either mention rain when it wasn’t measured officially in Philadelphia or fail to mention it when it was measured.

We also scored the temperature forecasts against climatology – the average temperature for the each of days. In other words, how did AccuWeather perform against “expected” weather.

Climatology got the slight edge – 20 to 19, with one dead heat.

After Day 13, the results aren’t real stellar. On 18 of the last 27 days, climatology was better than AccuWeather.

On 14 of those 27 days, the AccuWeather outlook failed to get within 3 degrees of the actual average temperature.

Looking back, the forecast we were most impressed with was the one for Aug. 28. AccuWeather called for 0.9 inches of rain that day; 1.04 fell.

The most impressive temperature forecast was for Sept. 5. It called for a high of 82 and low of 64. The actual official high was 82, and the low was 64.

The worst temperature forecast: The call was for 80 on Sept. 11; the actual, 94 at Philadelphia International Airport.

The current forecast goes all the way into November. We see no snow in it, nor any Sandys. In case you were wondering, Halloween night looks decent.

We’ll keep watching.

Tony Wood Inquirer Weather Columnist
About this blog

Tony Wood Inquirer Weather Columnist
Also on Philly.com
Stay Connected