Using Ventusky: The Most Effective Online Tool for Planning Spearfishing Trips

Ventusky allows users to check both historical data and forecasts for upcoming days, including wind strength, water temperature, current strength and direction, and a multitude of other parameters.

Basic Settings of the Ventusky Online Application:

Utilize the Search Function to Locate Your Spearfishing Spot

In the Ventusky application, the search function can be used to find your location, which you can add to your favorites via the sidebar (by clicking the star). Your favorite spots will be highlighted on the map, allowing for quick retrieval. In the search function, you can enter the name of your city or specific GPS coordinates (for example, in the format: 50.2, 40.3).

Timeline

Using the timeline at the bottom of the page, you can control the data displayed on the map. On this timeline, you can select the forecast period for which you want the data to be displayed. Use the buttons to play the animation or move the data forward or backward in the forecast period. The time is displayed in the time zone configured on your computer.

Altitude

Generally, you will be more interested in what is happening in the atmospheric layer closest to the Earth’s surface. However, if you are a pilot or have a keen interest in meteorology, you will likely appreciate the ability to view data from different levels above the Earth’s surface. To display this data, you can use the contextual form titled Altitude. This setting is only available for temperature and wind measurements.

Units

To modify the units of measurement (for example, from km/h to m/s or from °C to °F), click on the scale in the bottom right corner.

Select a Model

In the bottom left corner, you can select your numerical model. You can choose data from the ICON, GFS, and GEM models. The Automatic option allows for automatic switching between the ICON and GFS models to always provide data in the highest possible resolution. The ICON model is calculated at a higher resolution than the GFS but is only available for the next 72 hours and only for certain values. For longer periods or to display certain values (such as CAPE, Snow Cover), you need to switch to GFS, and selecting Automatic mode ensures automatic switching between models. The models offered are among the most accurate in the world, and it is recommended to follow and compare the calculations of all models. Below is more detailed information on the differences between the models.

Cumulative Precipitation

Precipitation is always displayed for a specific time period. For example, if you choose to display precipitation for 12:00, the value shown is the total precipitation for either the previous hour or the last three hours (or since a specific date). You can use the toggle option to change the time period for cumulative precipitation either in hourly accumulation (only for the ICON model), over three hours, or from a specific date.

Sidebar

In the sidebar, you can display more detailed information about the location. The sidebar appears after clicking on a city or location of your choice on the map. The data in the sidebar is displayed in the local time of the location in question (unlike the data on the map, which is displayed in the time zone configured on your computer).

Keyboard Shortcuts

Ventusky supports several keyboard shortcuts. You can try the following keys:
You can easily change the time with the arrow keys (← and →).
The P key toggles the presentation mode (hiding the graphical interface). This function is very useful for presentations.
The G key shows/hides grid values on the map.
The M key allows you to change models.
The W key toggles wind animation.
The I key toggles weather map interpolation.

Ventusky Video Tutorial

How to effectively use the marine weather application Ventusky for spearfishing? For a good video tutorial, it is recommended to watch the video by Stephane Dudon, an expert in spearfishing who excels at explaining the basics of the sport. Stephane is regarded as a knowledgeable instructor in spearfishing: humble, highly experienced, and passionate about the activity.

Here is his tutorial video on the Ventusky application:

Feel free to visit his YouTube channel; his videos are a delight for any spearfishing enthusiast.

NUMERICAL MODELS

To forecast the weather, a meteorologist must understand basic variables such as temperature, pressure, humidity, and wind current. The atmosphere is a physical system whose behavior is governed by the laws of physics and can be described using mathematical equations. These equations are extremely complex, and high-performance computers are required to solve them. The solutions to these equations are obtained using numerical models that calculate the future evolution of weather (temperatures, pressure, precipitation, etc.), with input data sourced from weather station observations or satellite data.

In the Ventusky application, you will find data from the American GFS model, the Canadian GEM model, the German ICON model, and several regional models (ICON EU, COSMO, NBM, HRRR). When interpreting model data, it is important to remember that the numerical model predicts the atmosphere in a simplified form.

ICON Model

This is a global model developed by the German National Weather Service (DWD). The model’s resolution is approximately 13 km. It runs every 6 hours. The regional model, ICON-EU, uses a grid of 7 km. Additionally, it is updated every 3 hours. This makes it the most useful model, readily available and covering all of Europe.

GFS Model

This is a global model developed by the National Oceanic and Atmospheric Administration (NOAA) in the United States. The model’s resolution is approximately 22 km. Calculations are performed in three-hour intervals for 10 days. The model is updated every 6 hours.

GEM Model

This is a global model developed by the Canadian Meteorological Centre (CMC). The model’s resolution is approximately 25 km. Calculations are performed in three-hour intervals for 10 days. The model is updated every 12 hours.

HRRR Model

This is a regional model developed by the National Oceanic and Atmospheric Administration (NOAA) in the United States. The model’s resolution is approximately 2 km. Calculations are performed in one-hour intervals for 16 hours. The model is updated every hour.

EURAD and USRAD

Two models, EURAD and USRAD, are based on current radar and satellite readings. These models can accurately show current precipitation in the United States and Europe. The models are updated every 10 minutes.

DESCRIPTION OF VARIABLES

Temperature

For these output data, the temperature is indicated for 2 meters above the ground (or for another altitude, depending on the settings). The calculations take into account the terrain (altitude), but with a lower resolution than reality. Therefore, models cannot differentiate, for example, the temperature at the top of a mountain or in a sun-baked city square. The general rule is that city centers are 1 °C to 3 °C warmer than surrounding areas or natural landscapes. Significant temperature differences over a small area are primarily caused in winter by inversions. A brief but noticeable cooling can also occur after a local summer storm.

Precipitation

This output data shows total precipitation in mm for the previous 1 or 3 hours, or for a specific date (accumulated amount). Models do not differentiate between higher precipitation totals in certain mountainous areas or, conversely, light drizzles due to fog and low cloud cover. Forecasting precipitation totals for local storms is challenging. The numerical model cannot accurately calculate the formation of local thunderstorm cells. In conversions to snowfall, 1 mm of precipitation is approximately equivalent to 1 cm of snowfall.

Radar

The radar layer shows current precipitation intensities based on real or predicted datasets. This output utilizes not only radars but also numerical models and satellite imagery to enhance coverage over oceans and certain land areas. Precipitation intensities are described by colors ranging from blue for low precipitation rates to red for very high rates. Strong colors (red) should be interpreted with caution as they may indicate not only heavy rain or snow but also thunderstorms, hail, strong winds, or tornadoes.

Cloud Cover

This output data shows cloud cover in percentages. Cloud models are very difficult to predict. The calculations also include forecasts of high cloud cover. A cloud cover of 100% means an overcast sky. However, if the sky is covered by a thin layer of clouds and the sun shines through, the sky is still considered overcast, even if it appears sunny at first glance.

Wind

The map illustrates the average wind speed or the maximum wind speed (called “gusts”) at 10 meters above the ground. Models operated by NOAA (GFS, HRRR) calculate with a 1-minute average. However, other models (ICON, GEM) calculate with a 10-minute average. This can cause differences between each model. The highest sustained wind value over 1 minute is approximately 14% higher than the sustained wind over 10 minutes for the same period. The calculation does not account for exposed areas (hilltops, open fields) where wind speed will be higher than in a city or valley. Localized increases in wind speed during storms are also not factored into the model calculations.

The direction and average wind speed are illustrated on the map by current lines.

Pressure

The calculations illustrate atmospheric pressure values at sea level. The output data differentiates between anticyclones and depressions as well as pressure gradients, which influence wind speed.

CAPE

When there is a possibility of storm formation, it is advisable to monitor CAPE values. It represents the potential energy in the atmosphere. It helps establish the level of atmospheric instability. The higher the values reached, the greater the likelihood of storm formation. Values below 300 are low, between 300 and 1000 are moderate, 1000 to 2000 are high, and over 2000 are very high, indicating a strong probability of severe storms. Storm formation is influenced by several other factors, but CAPE is an important indicator.

Freezing Level

The altitude in meters at which the temperature drops below freezing is illustrated on the map. This altitude greatly influences the state of precipitation. At altitudes above this level, precipitation generally occurs in solid form (snowflakes, ice crystals). Conversely, at lower altitudes, precipitation occurs in liquid form. However, this is not always the case. In some instances, snowfall can also occur at lower altitudes. This is because snow does not immediately melt at temperatures above freezing but does so gradually. Therefore, primarily in cases of low humidity, it can snow up to 400 m below this altitude. During temperature inversions, freezing rain can fall at this altitude.

Snow Cover

This data illustrates the expected height of snow cover. Forecasting the evolution of snow cover is very complex, and the indicated values may differ from the actual values achieved (even by several centimeters). The calculations take into account the terrain (altitude), but with a lower resolution than reality. Therefore, the model cannot display the exact height of snow cover in mountainous areas, where it varies significantly.

Waves

The application displays two types of waves: swells and wind waves. Waves that move away from their origin and are not caused by local winds are called swells. Waves caused by winds at that specific location are called wind waves. In the application, wind waves are marked in white and swells in black. This feature allows you to quickly find areas where significant wind waves are moving in a different direction than swells. The significant wave height is the average height (from trough to crest) of the highest third of the waves. Given the variability in wave height, it is likely that the largest individual waves will be slightly less than double the significant wave height reported for a given day. The wave period is the time interval between the arrival of consecutive crests at a stationary point.

Humidity

Relative humidity is indicated at 2 m above the ground. Humidity is the amount of water vapor present in the air. Relative humidity is expressed as a percentage (a higher percentage means that the air-water mixture is more humid).

Air Quality

Air quality is indicated at 10 m above the ground. Several compounds are available (PM2.5, PM10, NO2, SO2, O3, CO, and dust). Air quality is primarily influenced by particles (PM2.5 and PM10) during winter or by tropospheric ozone (O3) during summer. The model’s resolution is lower than reality. Therefore, the model cannot differentiate, for example, pollution near a highway or in a city center. Localized air degradation is also due to homes equipped with wood or coal-burning stoves. However, the model is unaware of these extremely localized sources of pollution.