The National Weather Service has developed a powerful tool that allows users to create custom weather maps that show everything from temperatures to snow totals. The tool's most excellent feature, by far, is the ability to track future weather along the path of one's road trip.
The tool, called the Enhanced Data Display (or EDD), is still in its experimental stages, so the application will occasionally go offline while meteorologists and technicians tinker with it. When it's online and in good working order, though, the application is perhaps the most powerful tool available on the agency's website.
The EDD allows you to map out everything from radar and satellite imagery to forecasts, current weather observations, and even upper-air soundings taken from rawinsondes attached to weather balloons. Of all of the EDD's excellent features is a nifty tool hidden behind a traffic sign up on the top-right portion of the application, called the travel hazard forecast.
When you click the traffic sign, a window pops up that allows you to enter the beginning and endpoint along your planned drive. Much like Google or Bing, the feature automatically takes the shortest route possible—if you plan driving from Washington to St. Louis, for example, and you'd like to visit Aunt Edna in Cleveland, you'll have to add Cleveland as a waypoint.
In the above example, I chose a to take a trip from Sault Saint Marie, Michigan to Caribou, Maine (two super popular destinations), with stops in Detroit and Cleveland along the way so I don't have to cross into Canada and void my American street cred. The resulting map shows you three different features—an icon, a data point, and travel conditions between cities on your route.
The application uses the distance and time of your trip—1,695 miles and 25 hours, in this example—to calculate the weather at certain points along your route. These points are plotted out every dozen miles or so, and they show you the weather conditions expected at that point (wind, snow, rain, storms, fog), a data point of your choosing (forecast temperature, forecast snowfall amount, wind speed, etc.), and the impacts you'll encounter between cities.
The roads are shaded in colors much like a traffic map on a news website—the colors range from green to red depending on how severe the hazards. If you're driving under clear skies and calm winds, the road will be green, while roads will gradually fade to red as you drive headfirst into a blizzard.
When you hover over one of the waypoints along your trip, it will show you the time you should arrive at that point (note: this assumes you don't make any stops and don't hit traffic), and gives you the weather for that time. For example, if we leave Green Bay at 2:36 PM, the application estimates that we'll arrive in Chicago around 7:00 PM; we'll arrive in the aptly-named Windy City to find a temperature of 40°F with winds of 25 MPH gusting to 35 MPH. If you were to keep driving, you'd hit Benton Harbor around 8:30 local time to find rain/snow showers with stiff winds.
All of the features offered by the EDD are impressive—and come with the quality of a National Weather Service forecast, rather than a shady "forecast" culled by a third-party app—but the travel hazards forecast takes the prize for what could become one of the most useful weather tools on the internet. It takes away the guessing game that can come from looking at twice-daily weather maps and extrapolating weather between here and there.