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Create Your Own Custom Weather Map Using WeatherScope

Andrea Dawn Melvin, Billy McPherson, Michael Wolfinbarger, and Renee McPherson, Oklahoma Climatological Survey
March 07, 2008 | Science News

To aid state agencies, public safety officials, K–12 teachers and students, and other decision makers in viewing weather information in a timely fashion on their personal computers, the Oklahoma Climatological Survey (OCS) develops easy-to-use visualization software and provides it free of charge for non-commercial use. OCS’s most recent weather data display tool is called WeatherScope.

This software is a powerful tool that provides the possibility of using real-time data with several investigations in the Weather and Water Course or as enrichment for students who would like to learn more about weather systems. As each new weather variable is introduced in the course, WeatherScope can help students visualize the relationship of the new variable with other weather factors. Some examples on using WeatherScope to the Weather and Water Course are included at the end of this article.

WeatherScope was created in the early to mid-1990s as a tool to visualize data from the Oklahoma Mesonet, a weather monitoring network that spans the state of Oklahoma. This tool can display weather and geographical information from sources both within and outside of Oklahoma. As a result, decision makers can view weather conditions “upstream”—that is, weather that has yet to enter the state—and make necessary preparations ahead of time.

The present WeatherScope application is a stand-alone web-based display and analysis system. It is available for Windows 2000, Windows XP, and Apple Mac OS X operating systems. For best performance, the computer should have 1 GB of RAM and an accelerated graphics card with 128 MB of VRAM. The software can be downloaded from Mesonet.

WeatherScope is an Internet application, so your computer must be connected to the Internet for the application to retrieve the data files used to build the maps. WeatherScope has the ability to update data in real-time, but also allows the user to specify the date and time of the map. This feature allows users to view the data as they become available without being concerned with manually downloading the most recent data.

Instead of generating static images on a server, the visual displays are generated on the customer’s machine. Once “raw” data are located on the user’s personal computer, images are created on the fly. The images can be zoomed and panned, and data levels can be turned on or off. In addition, decision makers can customize their weather maps, allowing them to determine what information is pertinent to their needs.

WeatherScope can be used for many applications in meteorology, geosciences, and geography. This tool allows the customer to produce weather maps according to individual needs, which may range from tracking severe weather using standard station plots and a loop of radar images to tracking the freezing line during a winter weather event.

Weather data can be displayed as maps or as time-series graphs in WeatherScope. The maps can include wind vectors (directional arrows with the length representing the wind speed), a color gradient, line contours, or simply the data themselves. Radar data can be displayed on the same map as other data, such as rainfall, wind, and air temperature.

Map overlays can be displayed as lines (e.g., highways, county boundaries) or points (e.g., cities, weather station locations) to provide a geographical context for the weather data. Overlays and data layers can be arranged in the legend such that a layer can be above or below another layer. Also, the user can change the translucency (or opacity) of layers. For example, radar data may cover up point data (e.g., air temperatures), but if opacity is set to less than 100%, then the point data are allowed to show through.

While it may be instructive to read a description of a cool piece of software, how about if we build a sample map together. (Editor's Note: You may want to open the WeatherScope application in a separate window, so you can follow these instructions as you work with weather map.) After you have downloaded and installed WeatherScope to your computer, launch the program either by selecting it from your Start Menu (Windows) or double-clicking on its icon (in the Applications Folder on your Mac). For the most part the labels used in the software are the same whether you are using the Windows or Mac version. But in a few cases there may be slight differences (e.g., one may use the term Loop while the other uses Animate). To minimize confusion, the following example will use the text provided in the Mac version.

Building Your Map

WeatherScope will begin with a default map that includes the county borders of Oklahoma. While that might work perfectly for an Oklahoma teacher, the software does work beyond the borders of Oklahoma.

Changing Geography

We will begin by deleting the Oklahoma map. Select Oklahoma County Borders in the legend. Press the Delete key. To add the U.S. State borders, select New Shape from the Product menu. A dialog box will appear with elements to customize your selection. Make the following selections: Data Set – United States Geography, Region – Continental U.S., and Feature – State Borders. You can increase the thickness of the line or change the line color. When you have completed your selections, click the OK button. You should see a map of the state outlines. If you don’t see the whole U.S. on your screen, then select Continental U.S. in the legend and choose Zoom to Fit from the Map menu.

Adding Observation Data

Let’s start by adding air temperature values to our map. Select New Observation from the Product menu. Again, a dialog box will appear with elements to customize. Make the following selections: Data Set – NWS Surface Observations, Variable – Air temperature, and Units – degrees Fahrenheit. Between the Data Set and Variable fields you will see a text box called Variable Filter. Sometimes the number of variables listed in the Variable menu can be very high. The Variable Filter box lets you type in part of the variable name to decrease the number of choices in the Variable Menu. So for instance, you could type in “temp”. The Variable menu will display Air temperature, Dew point temperature, Wet-bulb temperature and a few other calculated temperatures, but will not list rainfall or pressure. In the dialog, you will notice an element called Position with nine radio buttons. This allows you to select where you want the observation value to be displayed at the station. In this example, click the top left position. You can choose a color for this data by clicking on the colored box and making your color choice. When the Outline box is checked, either a white or black outline will surround the text of your observation. This makes it easier to view the numbers when you have several data layers on your map. Precision refers to the number of decimal points to be displayed. Normally, to avoid clutter on your map, you would set this to zero. The major exception to this rule is when your variable is Rainfall. Rainfall is such a small quantity that viewing the data in decimal form can be beneficial. When you have completed your custom selections, click the OK button. In a few seconds, you will see values of air temperature displayed across your U.S. map. If you want to see additional data values, you can repeat these steps, but change the variable displayed.

Color Gradient

WeatherScope helps with data analysis by giving you the option of viewing the data as a color gradient. Any variable can be viewed as a color gradient by selecting New Gradient from the Product menu. A dialog box will appear with elements to customize. Make the following selections: Data Set – NWS Surface Observations, Variable – Air temperature, and Units – degrees Fahrenheit. You can set minimum and maximum values for the gradient by deselecting the Auto box and entering your values. But for this example we will use the Auto feature. Setting min and max values are important if you want the data values to always be a particular color. This is helpful when animating the data. You have the option of making a custom color scale by clicking on a triangle on the color scale then clicking the Color box and choosing a new color. Opacity refers to how intense the colors will be displayed. The lower the percent value you select, the more muted the colors will become. When you have made all your selections, click the OK button.

You will notice that the colored data have hidden your temperature values. WeatherScope works with layers of data. Your last addition to the map is always displayed as the top layer. A good rule to use is to place your color gradient layer below your geographic layer. For our example, click and drag the color gradient icon for air temperature in the legend and place it below the State Borders layer. You should now be able to see both the air temperature values and the state borders.

The color gradient “bleeds” over the edge of the state borders. This can be cleaned up with a simple modification to the State Borders properties. Double click on the State Borders icon in the legend and the properties dialog will appear. Click the Mask Borders box and click the OK button. The color gradient data now stay within the boundaries of the State Borders.

Wind Vectors/Wind Barbs
Wind data can be viewed in two ways, either as vectors or as wind barbs. Vectors are displayed as arrows pointing in the direction the winds are blowing. The length of the vectors indicate the wind speed, with a long arrow representing faster winds. We can add wind vectors to our map by choosing New Vector from the Product menu. A dialog box will appear with elements to customize. Make the following selections: Data Set – NWS Surface Observations, Variable – Winds at 10 meters, and Units – miles per hour. Move the Size slider to Large. Click the OK button to display the wind data. If the winds are light, you may have to zoom in on a portion of the map to see the arrows. Click on your state to see the winds. Use Zoom To Fit from the Map menu to see the whole map again.

Wind barbs are the traditional method that meteorologists use to view wind data. Double click on the Winds icon in the legend. Uncheck the Draw As Arrows box. Click the OK button. You will see a mess of wind data. To see the actual wind barbs you will need to zoom in on a section of the map.

Before we move on, let’s remove the wind data to make the map less cluttered. Click on the Wind icon in the legend, then press your Delete key.

Radar Data

The most important information needed for tracking storms is radar data. In WeatherScope you can add radar data to any other data you may have on your map. Select New Radar from the Product menu. You will see the familiar dialog box of properties. Make the following selections: Data Set – NEXRAD Level III and Product – Base reflectivity 1. Because no one radar covers the entire U.S., we will need to select a specific radar to view. Let’s use the Filter box to help narrow down our choices. You can type in a state’s abbreviation or a few letters of the radar name if you know it. Let’s type in MO for Missouri. Click on the pull-down menu for Site. You will see a list of all radars that have MO in their names. The listed is sorted by state abbreviation. Select MO-St. Louis from the list. Click the OK button. Zoom in on the state of Missouri. If there are no storms out today, you may only see some speckled dots of yellow and orange near the location of the radar.

Inspector

You may be wondering, “How do you know what value the colors represent on the color gradients or radar data?” WeatherScope provides more information about each data level in the Inspector. The Inspector can be found by choosing Show Inspector from the Window menu. Whichever data layer you have selected in the legend will be displayed in the Inspector. For example, choose the Radar icon in the legend. You will see a color scale that indicates the value of each color displayed on the radar layer. Click on the Color Gradient icon. Now as you move your mouse around the map, the value of the color under your cursor will be indicated in the Inspector.

Animation

Any data displayed in WeatherScope can be animated to see how the data change with time. Double click the date/time in the legend. The date and time displayed will be the current time provided by your computer. If your computer clock is off, then the date/time displayed in WeatherScope will be off. Set the Loop (Duration for Windows users) value to 3 hours before date. Set the Interval to 5 minutes. Click the OK button. Choose Zoom to Fit from the Map menu. Select Show Animator from the Window menu. A floating toolbar will appear to operate the animation. Press the Play button to begin the animation.

Each data set has its own update cycle. Due to the different update cycles, the data will animate at different times. For instance, National Weather Service (NWS) data are collected once an hour. Radar data are collected at different cycles. For example, during calm weather the radars update every 10 minutes. When storms are occurring, the radar can update every 4, 5, or 6 minutes, depending on which mode the radar is set. In our example we set the Interval to be 5 minutes. This interval is shorter than the update cycle for the NWS data but could be exactly the update cycle for the radar.

Double click on the date/time in the legend to get the properties dialog back. For Interval, select Sync To from the pull-down menu. The remaining text box and pull-down menu on this line disappears and is replaced by a new pull-down menu. In this menu, you will find a list of all the data layers you have added to your map. Because we don’t know if the radar is updating every 4, 5, 6, or 10 minutes, we can have WeatherScope animate based on the available files for the radar. When using the Sync To option, the data layer you select will animate more smoothly and won’t skip over a data file that doesn’t match our specified interval. Click the OK button and continue to view your animation.

Archived Data

Up to this point we have viewed only data from today. WeatherScope also displays archived data. The Oklahoma Climatological Survey has archived data stored on servers that you can access. The National Weather Service data archive is complete from 1940 to the present, the Oklahoma Mesonet data archive began on January 1994, and radar data are only available for the last week. We do have some specific events online that contain radar data. For instance, May 3, 1999 was a major tornado outbreak in the Great Plains. We have archived several radars over the area affected in this event.

Let’s look at the May 3, 1999 event. Double click on the date/time in the legend. Change the date to 5 3 1999. Set the time to 5:00 PM. Change the Loop to 6 hours after the date. Click the OK button. Double click on the Radar Icon in the legend. Type OK in the Filter box. Select OK-Oklahoma City from the pull-down menu. Zoom the map to Oklahoma. Watch the animation as the storms form in southwest Oklahoma and continue to move across the state.

FOSS Weather and Water Applications

The following are some suggestions from Terry Shaw, a FOSS developer, for integrating Weatherscope into the FOSS Weather and Water course.

  • When students study solar angle and beam spreading in Investigation 3, they can examine the relationship between latitude and air temperature (as an indirect indication of solar radiation).

  • In Investigation 6, students can study the relationship between temperature, pressure, and altitude by overlaying these three data sets on the map, using a gradient for the elevation and numerical data for the air temperature and pressure. By looking across the same latitude, students will be able to see how elevation affects the other two variables. They can also correlate relative humidity with cloud cover (radar data) and rainfall during the past hour or three hours.

  • In Investigation 7, students are able to “observe” sea breezes and land breezes at weather monitoring stations along the coasts at different times during the day.

  • Students can use a real-time air pressure map, replacing one on page 53 of the Lab Notebook (Investigation 8) and then check their predicted wind direction and speed using actual wind vectors.

    One lesson students will learn by using the WeatherScope software is that relationships between weather variables are seldom simple. For example, although students will be able to notice general patterns, they will find that wind direction and speed are not determined just by air pressure differences as indicated by pressure readings from weather stations. Winds are also influenced by many other factors including topography, circulation around high- and low-pressure areas, the Coriolis effect, and prevailing winds.

  • The animation feature in combination with radar data can be used to show weather movement as an extension of Investigation 9. Students can “see” fronts progress across the country and begin to make predictions based on the data on their computer screen. The archive feature allows information to be stored for later use, (e.g., to check predictions or save interesting weather patterns).

Conclusion

WeatherScope is a powerful tool for all weather enthusiasts. The next time interesting weather is headed your way, turn on your computer and build a WeatherScope map. This article only touched on a few of the features in WeatherScope, so it is suggested that you check out the online Help guide for more information. Choose WeatherScope Help from the Help menu to find out more about using WeatherScope to its full potential. Send questions or comments about WeatherScope or weather questions to earthstorm@mesonet.org.