"Will it rain?" This might be one of the most frequently asked questions in daily life. As a result, most people have looked at a precipitation radar at some point. On Weeronline and Weerplaza, the radar page is among the most visited, and the popular Buienalarm app is specifically designed to answer this question.
In winter, knowing the type of precipitation—rain, snow, or freezing rain—becomes even more crucial. To address this, Infoplaza's WeatherTech department has developed a module that adds precipitation types to radar images. Let’s take a closer look at how it works.
For current precipitation imagery, Infoplaza uses radar images from the KNMI. These images contain echoes that can be interpreted as precipitation. But how are these echoes formed?
A radar emits radio waves, which bounce back when they hit a water droplet, ice particle, or snowflake. By measuring the time between the emission and the return of the radar wave, along with the signal strength, information about the precipitation’s intensity and location can be determined. By displaying all these echoes on a map, a radar image is created, where colors indicate the intensity of the precipitation.
At this stage, no information about the type of precipitation is available, which is a missed opportunity. Knowing the form of precipitation can be incredibly useful. Fortunately, Infoplaza adds an extra layer to the radar image, making the precipitation type visible as well.
In a standard atmosphere, temperature decreases as altitude increases. However, in reality, the atmosphere often deviates from this standard. Air masses can overlap, creating temperature profiles that vary significantly.
Air layers can exist above warm layers or vice versa. This layering has a direct impact on the type of precipitation that falls through them.
Hail is also a type of precipitation but typically occurs in combination with rain or snow. Infoplaza uses a separate model to analyze hail.
Infoplaza uses the energy method to determine precipitation types. In this method, a virtual snowflake is tracked as it falls through the atmosphere. Depending on the temperature and humidity in each layer, the snowflake may remain intact, melt, or evaporate in dry conditions. In cases of multiple atmospheric layers, a melted snowflake can refreeze in sub-zero temperatures or continue falling as supercooled water, leading to freezing rain or ice.
The final precipitation type is determined by analyzing the thickness of these layers and the temperature differences between them.
The precipitation type model relies on data from Infoplaza’s unique Optimal Model. Special attention is given to the lowest 200 meters of the atmosphere, as this is where the final precipitation type is defined.
The model’s results are cross-checked with real-time data, such as temperature and wet-bulb temperature, to make adjustments.
Or more accurately, this is the second-to-last adjustment. In the final step, KNMI weather station data is checked to ensure it matches the model’s outcome. If discrepancies are found, real-time observations override the model.
Once all checks are complete, the precipitation type is overlaid on the raw radar image. This enriches the standard radar visuals with additional information. These enhanced images are available via Weeronline, Weerplaza, Imweather, and specific Infoplaza client dashboards, such as those tailored for road maintenance during icy conditions.
Adding the precipitation type is not only beneficial for users but also invaluable for Infoplaza meteorologists. For example, it provides road maintenance meteorologists with extra insights during winter, enabling them to deliver better-informed advice.
While the Infoplaza precipitation type model is highly reliable, it is not flawless. A common challenge occurs with winter showers over the North Sea, where temperatures are well above freezing, but wet snow still falls.
Noud Brasjen, who developed the precipitation type model, continues to fine-tune it to achieve maximum accuracy. He predicts that artificial intelligence (AI) could help resolve the North Sea issue. AI excels at pattern recognition, which could prove invaluable here.
The precipitation type radar has repeatedly demonstrated its value in winter scenarios. Knowing whether it will rain, snow, or sleet is crucial, as it directly impacts safety, decision-making, and preparation in situations like traffic, events, and infrastructure management.
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