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Nooly weather app claims to-the-minute forecast accuracy

Custom algorithms are designed to tell you when rain will start or turn into a thunderstorm. But don't get your hopes up for predicting the future.


Can weather forecasting do better than "30 percent chance of showers"? What if it could tell you the minute it will start raining?

"Nowcasting" app Nooly claims it can tell you when precipitation will start and end with an accuracy of five minutes. It can also tell you when storms will intensify.

Nooly coverage, currently limited to the U.S. and Canada, can focus on an area within 0.4 square miles of your location.

It delivers 240 million predictions every five minutes based on a custom-designed algorithm that crunches satellite and radar data from NASA and NOAA. After a year of beta testing with some 50,000 users, it's now available for free to iOS and Android users.

"Being so hyperlocal brings with it wide range of challenges," Nooly CEO Yaron Reich said in a release. "We had to adjust our algorithm for different cities, like Seattle, which experiences shallow, constant rain, and New York, which often sees bursts of rain lasting a few minutes and impacting only a cluster of city blocks.

"San Francisco is also a tricky city, with a mostly calm climate, though the weather can change in very specific streets and neighborhoods. Hyperlocal is challenging, but obviously key."

This rather barebones app offers local forecasts in a variety of formats -- with Google maps, graphs, and tables with times in 5-minute, 15-minute, or hourly predictions for the weather, which includes temperature, precipitation, humidity, wind speed, and direction.

You can also search by location and add places to a favorites list. But there are no fancy graphics or video forecasts.

When I tried the app, Nooly gave me a fairly accurate picture of conditions outside, but snow flurries began more than 20 minutes before the estimated time.

Nonetheless, I was about to declare that better than The Weather Channel or AccuWeather until I noticed that Nooly got the local temperature in Montreal wrong, repeatedly listing it at minus 16 C (3 F) instead of the actual reading of minus 9 C (16 F), which I confirmed with a thermometer.

That's a big discrepancy -- a long-johns false alarm. Maybe the local version of the algorithm needs tuning.

Nooly's minimalist user interface on a Samsung Galaxy tab running Android also left a few things to be desired. I couldn't get it to display in landscape mode, menu buttons are small and hard to select, and the "home" button may not always give you the conditions at your default location. Performance was sluggish.

Still, with these kinks ironed out, Nooly could deliver on the promise of a to-the-minute forecasting service. Just don't make plans around it for now.