Listen to article \u2022\u00a00:00 min<\/p>\n
That puny pulse of rain Wednesday morning may have been a welcome watering for the plants and grasses and evidently didn\u2019t cause problems \u2014 except for the heavy hitters in the weather-app universe.<\/p>\n
About 6 a.m., the Weather Channel had rain ending around 7:15 a.m. in Philly \u2014 except it wasn\u2019t raining at the time in town, and the bulk of the rain was a few hours away.<\/p>\n
Just before 9 a.m., AccuWeather predicted that rain would start at Philadelphia International Airport<\/a> in 51 minutes. But it already was raining at PHL, according to the National Weather Service\u2019s official rain gauge. And the apps were at odds over the temperature. <\/p>\n At the time, the Weather Channel reported that the airport temperature was 54 degrees. AccuWeather said it was 51. The official reading was 53. <\/p>\n Such imprecisions and disagreements among apps should be \u201cexpected,\u201d said Clifford Mass, a scientist at the University of Washington whose research specialties include numerical weather prediction and who is a frequent app consulter.<\/p>\n Nor is it surprising that legions of weather apps \u2014 including major providers like the Weather Channel and AccuWeather that have human backup and access to superior computer models \u2014 would quibble about what\u2019s happening outside.<\/p>\n It\u2019s not like app developers have spotters everywhere armed with body radar and temperature sensors.<\/p>\n For whatever their flaws, the apps should be appreciated as \u201can amazing technical achievement,\u201d said Mass.<\/p>\n AccuWeather and the Weather Channel are among 35 companies registered with the National Weather Service, but the actual number of smartphone weather apps, including default apps and those maintained by media outlets in Philly and elsewhere, number in the thousands. <\/p>\n What they have in common is strong dependence on the U.S. government.<\/a> And limitations.<\/p>\n Be aware that for an app, even capturing the \u201cnow\u201d condition essentially is a forecast. Temperatures in most cases are best approximations. If you\u2019re using the apps to time a walk or run, ride a bike, or put off something you don\u2019t feel like doing outside, proceed with caution.<\/p>\n It is all the result of computing power, meteorological expertise, a dash of artificial intelligence \u2014 and the considerable contributions of the nation\u2019s taxpayers.<\/p>\n What those weather apps can do<\/p>\n Once upon a time not all that long ago, micro-local temperature readings in public spaces were the province of random, out-of-kilter public thermometers, often on bank buildings (for whatever reason). <\/p>\n These days, those smartphone apps offer readings for wherever you are, with second, third, fourth opinions, ad infinitum, literally at fingertips. Along with the winds, relative humidity, discomfort levels, barometric pressure, they offer forecasts ranging from the next few minutes to July 4 weekend.<\/p>\n No apps, nor Punxsutawney Phil, nor anyone else, have yet mastered long-term outlooks with any level of precision<\/a>, but Mass said that with short-term forecasting, \u201cit\u2019s stunning how good\u201d the apps have become. <\/p>\n For its part, the weather service says it isn\u2019t competing with the commercial services \u2014 which carry the agency\u2019s alerts and warnings. To the contrary, a spokesperson said, it is providing \u201cfoundational data\u201d that allows companies to provide \u201cspecialized services\u201d to the public. <\/p>\n The weather service issues statements and warnings for short-term threats, such as approaching heavy rain, severe thunderstorms, and tornadoes, but it\u2019s generally not in the minute-cast game and wouldn\u2019t bother with prosaic pulses of rain like Wednesday\u2019s. <\/p>\n In Mass\u2019 view, the major private companies are producing forecasts that are better than the weather service\u2019s. <\/p>\n And that would have a lot to do with the weather service, which is the No. 1 supplier of the raw material that includes short- and long-term computer model runs, quality-controlled temperature data, satellite imagery, and all-important radar. <\/p>\n How the weather apps make their forecasts <\/p>\n \u201cAll of our data is open access and free to use,\u201d the weather service spokesperson said, all formatted to make it \u201ceasily accessible for private sector companies to develop mobile apps.\u201d<\/p>\n Said Dan DePodwin, AccuWeather\u2019s vice president for forecast operations, \u201cThe weather service plays a critical role.\u201d <\/p>\n The government freebies include forecast guidance from 31 forecast models. <\/p>\n That input is \u201cjust the first step in the forecast pipeline\u201d for the major apps, said Eric Floehr, head of Intellovations Inc., a software development company that specializes in weather and climate. <\/p>\n