Make a folder on your desktop called imgkap and put imgkap.exe in it. This program is discussed at that link as well as in the OpenCPN Manual at this link /ocpn/imgkap. Download a copy of imgkap.exe (Windows binary, v 1.11, 3.5 MB) from /inlandwaters/imgkap. I do not know of a Mac equivalent, but there could be something.īelow is the step by step procedure, and here is a video that shows the steps in action using a later 24h surface analysis. Once the file is made, it will open in Mac or PC versions of OpenCPN. kap file format that is used in the RNC echart format, also called BSB. We will use a free utility called imgkap.exe for the PC. The explanation of the process is outlined below, followed by a video showing each step in action. The final product should in principle open in any echart viewer. Our electronic charting and weather training now use OpenCPN for the in class exercises, so the goal at hand was to develop a method for loading weather maps into OpenCPN. The procedure below makes a file that will open in any echart viewer. All of these solutions can create a weather map echart, but they would each be unique to their own viewers. In principle the free program Sea Clear can do this, but I have not yet succeeded with that. Other commercial products also offer this, including Ocens MetMapper, and Polar View. That program still has this functionality, but the demo version no longer includes this option. In that discussion we had recommended the program Memory-Map Navigator as a way to do this as it was possible with their free, demo version. We discuss this in Modern Marine Weather in Section 7.2 called Georeferencing Weather Maps. Another important application is overlaying the GFS grib forecasts on actual NWS forecasts to evaluate the GFS data-in areas where we do not have digitized NWS forecasts in the form of NDFD gribs, in which case this could be done more easily by just comparing gribs. It also facilitates reading wind and pressure from the map at places where none are shown. With the latest surface analysis and forecast maps in an echart viewer, we can see our GPS position right on the map and plan routes across the weather patterns. So best bet is go the new article unless you have specific interest in the use of georeferenced images in the kap format as used with NOAA echarts. It not only allows image display with convenient georeferencing, but also includes a direct link to many maps online that show up automatically georeferenced in OpenCPN. The "new" method is a remarkable plugin to OpenCPN called Weatherfax, which has apparently been available for some time and I just did not know about it. There will shortly be here a link to a new article. For example, in summer, a “cold front” might actually have a 90☏ (32☌) air mass behind it if the warmer air mass ahead is 95☏ (35☌).Since posting this note (and spending much time on figuring out how to do this!) we have learned from a comment that there is indeed a very much easier way. The terms "cold" and "warm", however, are relative. Phrases like "ahead of the front" and "behind of the front" refer to a front’s motion – being "behind the cold front" means being inside the cold air mass, and being "ahead of the cold front" means being in the warm air mass the cold air mass is displacing as it moves. Boundaries between these air masses are depicted with lines called "fronts".įronts are usually detectable at the surface in a number of ways: winds often "converge" or come together at the fronts, temperature differences can be quite noticeable from one side of a front to the other side, and the pressure on either side of a front can vary significantly. In the section about the Origin of Wind, we have seen the source of the "highs" and "lows". However, there are some common features typically found in all of these images. Weather maps come in a myriad of styles, each providing different levels of information.
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