Human versus weather app – which is more accurate in the TCI?

By Paul Wilkerson

Why are weather apps wrong so often in the Caribbean?

I have been forecasting the weather for the Turks & Caicos Islands for the better part of eight years now. The number one comment/question I get? “My app shows it raining the entire time I am there, will it really be a washout for our trip?” Of the thousands of questions I have answered over the years, this one comprises probably 95% of everything asked. And this is a very valid question because it can alter how we go about our trip planning. It can range from anything as simple as adjusting attire to something as drastic as cancelling or delaying a trip.

With that question in mind, let’s discuss the origins of weather forecasting in the Western Hemisphere, and discuss why you see such a difference between a forecast a meteorologist puts out versus what that app on your phone shows. 

Weather predicting has been around for several thousand years. In the earliest times, humans didn’t have access to weather radar, satellite images, or the plethora of other data we have at our disposal today. Early forecasts were made simply by watching for recurring meteorological events throughout the year during each season. By surmising what was occurring in a particular season, the earliest forecasters could then watch for those same cues during the following corresponding season to build a library of potential weather forecasts.

In the United States, weather forecasting really came into being with the development of the first large-scale weather observation network in 1849. One hundred fifty stations comprised this first-of-its-kind network that reported weather conditions at regular intervals each day. By 1860, that network had ballooned to 500 stations across the U.S.

During that day and age, the human weather observer was the defacto “super-computer.” The information these stations provided lent greater abilities to begin forecasting weather into the future. By 1869, a telegraph service was creating weather charts based off the data provided by these weather observers. These charts were the catalyst of the modern weather forecast provided by people.

In early 1870, the U.S. Weather Bureau was created as part of the U.S. Army Signal Service. In 1890, the Weather Bureau was brought out from under the U.S. Army Signal Service and became a fully civilian-run agency under the Department of Agriculture. In July 1970, the name of the Weather Bureau was changed to the National Weather Service. At the same time, the National Weather Service was placed under the National Oceanic and Atmospheric Administration (NOAA) within the Department of Commerce where it remains. It comprises 122 stations across the United States and Puerto Rico. Each station is responsible for forecasting services for a pre-determined area that may encompass parts of several states and millions of people.

So why is there such a disparity in forecasts between meteorologists and the weather apps most people use on their phones? In particular, why is the forecast for the Turks & Caicos Islands so vastly different between the two entities? Why are weather apps wrong so often in the Caribbean? In general, this is due to the lack of actual weather data from reporting stations throughout the Caribbean. The apps that your phones utilize are pulling data from weather models.

For the Caribbean, the most often used models in forecasting are the American Global Forecast System (GFS), and the European Model (EURO). These models ingest real-time data from a Global Upper Air Network. In the United States, there are at least 92 stations providing this data, while only 10 stations stretched out across the Caribbean are providing data.

Globally, more than 800 stations are active. These stations send up balloons every morning and evening, collecting data between the surface and 80,000 feet or so, sometimes higher. When this data is transmitted back to the stations, it heads to super-computers in the U.S. and Europe, where the data is converted into weather forecast models that predict forecasts out 10 to 15 days in advance.

In the United States, weather apps tend to have more accuracy because they are utilizing this model data that is derived from at least 92 different points across the country. These 92 stations enable a really good picture of our atmosphere to be fed into computers that then work their algorithmic magic to produce forecasts for locations across the country.

Sunset at South Side Marina in Providenciales.

In the Turks & Caicos, unfortunately, there are no stations on the Islands. There also are no stations to the east and very few stations to the south or west. (Remember there are only 10 total in all of the Caribbean.) This means very little valuable data is available, and with that, error increases dramatically. Now imagine starting with this error/lack of data, and then trying to forecast it out into the future. The error generally grows, and as a result, you end up with highly erroneous model data for some parts of the Caribbean, which in turn is presented to you in your weather app on your phone. The forecasts on nearly all weather apps are produced by model weather data.

The flip side to these weather apps is found in a true meteorologist, and in some cases, weather enthusiasts who have studied a long time and have learned how the tropics react over the years. As meteorologists, we have access to the same data the weather apps are using to create those highly erroneous forecasts. As expected though, we have a significant advantage. We have access to satellite data, current weather observations, weather radars, aircraft weather reports, and so on. Many of us have been through college to learn about the atmosphere and how it behaves, and for many, in particular, the Tropics.

We are able to do what no computer can do. We can take our experience during our careers, lessons we have learned, our training, and consultation with colleagues, to provide forecasts for a location like the Turks & Caicos that are far superior to what a weather app will provide.  The weather knowledge we are able to apply is an invaluable tool in weather forecasting, and it really shines in locations where real-time weather data is sparse. Will we get the forecast wrong? At times, of course! The atmosphere is fluid, and Mother Nature doesn’t always cooperate.

Next time you take a look at your weather app and it calls for “gloom and doom,” try to remember how that information is developed. If you are ever concerned about the forecast for your trip, you are welcome to send me a message on the Turks and Caicos Weather Info page on Facebook. I would be happy to help ease your concerns.

As well, the TCI is in the early stages of developing its own National Meteorological Services through the Turks & Caicos Islands Airport Authority, led by Director of Meteorology Dr. Holly Hamilton. Its aim is to provide weather forecasts, warnings of hazardous weather, and other weather-related products for the purposes of protection, safety, and general information.

The government realizes that the country cannot continue to rely on other countries to provide data. As hurricanes and climate change make weather events more disastrous and dangerous, the TCI needs real time information provided by state-of-the-art equipment so that we know what is going to happen. This will allow for early warning and early action.

Paul Wilkerson is an American meteorologist and tourist who frequents the Turks & Caicos Islands. Along with his wife and two daughters, the Wilkersons stay actively engaged with Islanders throughout the year with his Facebook page Turks and Caicos Islands Weather Info.