Do You Need a Map?

Introduction to nowCOAST Worksheet

nowCOAST is a map-based gateway to real-time observations and forecasts of marine weather and oceanographic conditions. Using nowCOAST, you can quickly link to information about specific locations from many different sources. This exercise introduces the nowCOAST tool and provides some examples of how it can be used to retrieve various kinds of data for locations of interest.
  1. Link to the nowCOAST Web site at This opens the “Map Viewer,” which is one of the two main components of nowCOAST. You should see a satellite image of the continental U.S. with a superimposed map of the U.S. and an introductory message containing basic instructions. To get started, disable popup blockers for the nowCOAST Web site (if you aren’t sure how to do this, click on “More Information” in the upper right corner of the nowCOAST window, then click on “Help/Frequently Asked Questions”, and then select “Turning Off Popup Blockers” from the list on the left side of the screen). Now hide the introductory window by clicking “Instructions On/Off” in the upper right corner of the nowCOAST window.

  2. The image of the continental U.S. will probably have some colored areas, and may also have some light gray areas. The colored areas represent “Weather Radar Mosaic” data. A radar is an instrument that transmits a pulse of electrical energy in a particular direction and then measures the amount of energy that is returned to the transmitter location. The intensity of the returned energy is called “reflectivity,” and is related to the distance and composition of objects that reflect the transmitted energy pulse. The Weather Radar Mosaic shows combined information from many pulses transmitted at various angles, and provides an indication of precipitation, storms, and other atmospheric features.

    The gray areas on the map represent visible images obtained from geostationary operational environmental satellites (GOES) that sense radiant energy and reflected solar energy from the Earth’s surface and atmosphere. The images show the location of clouds and storms, and also can be used to estimate temperature at various points in the atmosphere (for more information about GOES, visit

  3. Notice the two boxes at the right and bottom of the map. The “Map Layers” box on the right contains a catalog of the various kinds of data that can be accessed through nowCOAST. Using the square boxes, you can control which data set locations are displayed on the map. Notice that the boxes next to “Weather Radar Mosaic” and “GOES Visible Image” contain check marks. This means that these data are visible. If you click on one or both of these boxes, the check mark will disappear, the map will be redrawn, and the data will no longer be visible.

    The “Map Tools” box at the bottom of the page can be used to manipulate the map display and select data in locations of interest. Let’s suppose that you are interested in oceanographic data near the island of Puerto Rico. Click on the “Zoom In” tool at the bottom left, then place your cursor near Puerto Rico and click once. The map will redraw, zoomed in toward Puerto Rico. Notice that the scale bar near the bottom left of the map reads about 515 mi. Zoom in again so the scale is about 256 mi. If your cursor wasn’t close enough to Puerto Rico, you can use the “Pan” tool to move the map around, or use the “Zoom Out” tool to go back and try again.

    Now let’s find what oceanographic data are available for this area. In the “Map Layers Box,” scroll down to “Geo-Referenced Links:” and click in the square box next to “Oceanographic” under the heading “Observations – In-Situ Stations.” The map should redraw, with little blue triangles scattered around. the coast. Notice that the round box next to “Oceanographic” now contains a black dot. This means that the Oceanographic Stations boxes are now the “Active Layer,” which means that you can use the “Link to Data” map tool to click on one of these triangles to link directly to a Web page containing data for that location.

    Select the “Link to Data” map tool (the lightning bolt) and click on the triangle near the southwest coast of Puerto Rico. A new window should open titled “9759110 Magueyes Island, PR” that contains graphs of water level, winds, barometric pressure, and air/water temperature. Below these graphs is a link to a table containing the numeric data for these parameters. You are now in the “Data Browser,” which is the other main component of nowCOAST. As you link to different data sources from the Map Viewer, the Data Browser keeps track of what you’ve seen so that you can browse backward and forward through the various pages of data.

  4. The “Jump Bar” at the top of the nowCOAST map page provides an alternative way to locate data. Using the same Puerto Rico example:

    1. Open a new nowCOAST page (repeat Step 1), turn the instructions off, and uncheck the square boxes next to “Weather Radar Mosaic” and “GOES Visible Image.”
    2. From the pull-down menu near the top of the page under “1) Location” select “Southeast” under “---Coastal Regions ---” (this is closest to Puerto Rico)
    3. From the pull-down menu under “2) Information” find the heading “GEO-REFERENCED LINKS”, and select “-Oceanographic” under “Observations - In-Situ Stations:”
    4. From the pull-down menu under “3) Variable,” select “Sea Surface Temp.”
    5. Since there is only one choice (“Real Time”) under “4) Time” click on the “GO” button next to “5).”

You should now have a zoomed in map of the southeastern U.S. coast with lots of yellow dots that correspond to stations that collect data on sea surface temperature. You should also see some blue triangles in locations of in-situ oceanographic observation stations. If you scroll down the “Map Layers” box, you’ll see that the boxes next to “Oceanographic” under “Observations - In-Situ Stations” are selected, making these stations visible and active.

Use the “Pan” tool to move the map to make Puerto Rico visible. Click on the triangle near the southwest coast of Puerto Rico with the “Link to Data” tool to link to the Web page containing data for this location. Again, you should see the window titled “9759110 Magueyes Island, PR.”

  1. Suppose that you are about to deliver a 55 ft-long power yacht from Puerto Rico to Bar Harbor, Maine, and want to know about weather conditions along the way. The big decision is whether to take an offshore route (which is most direct), or go via the Intracoastal Waterway (which is more protected). To check out the conditions and forecasts for the offshore option, use the “Zoom Out” and “Pan” tools to make the coast of eastern North America visible (the scale should be about 926 mi). Scroll down the “Map Layers” box and click in the square and round boxes next to “High Seas” (under “Surface Forecasts:”) to make this visible and active. Now you should see two polygons extending from the east coast of North America to about half-way across the Atlantic Ocean (alternatively, you could simply select “- High Seas” under “Surface Forecasts” in the “2) Information” pull-down menu and click “GO” to display the two polygons).

If you click inside the lower polygon with the “Link to Data” tool, a window will open containing the High Seas Forecast for the portion of the Atlantic Ocean west of longitude 35°W between latitude 3°N and 31°N, including the Caribbean Sea and the Gulf of Mexico. Clicking inside the upper polygon with the “Link to Data” tool will open a window that contains the High Seas Forecast for the portion of the Atlantic Ocean west of longitude 35°W between latitude 31°N and 67°N. Considering the 48-hour forecast high seas forecasts, would you recommend an offshore route or the Intracoastal Waterway?

  1. Use nowCOAST to find:
    1. The maximum winds forecast for the next 48 hours at a location approximately 150 miles east of Washington DC [HINT: Try the “Forecast Model Guidance: Meteorological” layer. Abbreviations are: DT = Date; HR = Time (24-hour clock); TMP = Temperature (°F); WD = Wind Direction (tens of degrees); WS = Wind Speed (knots); WS10 = Wind Speed at a height of 30 meters.]

    2. The maximum significant wave height forecast for the next 48 hours at approximately the same location as (a) [HINT: Try the “Forecast Model Guidance: Oceanographic” layer.]

    3. The highest water level predicted during the next week at station 8761724, Grand Isle, LA. [HINTS: Make the “Station ID” layer visible and zoom in so you can read the numbers. Use “Astronomical Tidal” predictions. Data are given in meters above mean lower low water (MLLW)]

    4. The five-day weather forecast for Curry County, OR. [HINT: Be sure the “Coastal Labels” layer (under “Map Background”) is visible, then zoom in until the county labels are visible; Curry County is the southernmost county on the Oregon coast.]

    5. The coastal waters forecast for San Diego, CA

    6. The offshore waters forecast for California waters from 60 nautical miles to 250 nautical miles offshore (Point Conception to Guadelupe Island).

    7. Most recent water temperature measured at NOMAD buoy (station 41002) located 250 nautical miles east of Charleston, SC.

    8. The particulate matter concentration at the webcam located at Point Reyes National Seashore (near San Francisco, CA). [HINT: The station ID for this camera is PNTRE-CAM]


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