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WeatherGraphix Interactive Weather Analysis System User's Manual Edition 3 May 1993 Software and Documentation 1992, 1993 Tim Vasquez ============================================================================ WeatherGraphix Interactive Weather Analysis System Tim Vasquez, P.O. Box 9808, Abilene, TX 79607 CompuServe 71611,2267 -- Internet 71611.2267@COMPUSERVE.COM -- Genie T.VASQUEZ1 Table of Contents (page numbers are for desktop published version only) REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 TERMS OF USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 REGISTERING A COPY . . . . . . . . . . . . . . . . . . . . . . . . . 2 OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Capture the data. . . . . . . . . . . . . . . . . . . . . . . . . 3 Access the data . . . . . . . . . . . . . . . . . . . . . . . . . 3 Run WeatherGraphix. . . . . . . . . . . . . . . . . . . . . . . . 3 INSIDE THE PROGRAM . . . . . . . . . . . . . . . . . . . . . . . . . 4 Active Level Commands . . . . . . . . . . . . . . . . . . . . . . 4 Radar Commands. . . . . . . . . . . . . . . . . . . . . . . . . . 5 Analysis Commands . . . . . . . . . . . . . . . . . . . . . . . . 5 Map Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Other Commands. . . . . . . . . . . . . . . . . . . . . . . . . . 7 SURFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 UPPER AIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 RADAR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Radar Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Echo Intensity. . . . . . . . . . . . . . . . . . . . . . . . . . 10 Radar Heights . . . . . . . . . . . . . . . . . . . . . . . . . . 10 CONFIGURATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 CUSTOMIZING THE PROGRAM. . . . . . . . . . . . . . . . . . . . . . . 12 Batch Files . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Station Database. . . . . . . . . . . . . . . . . . . . . . . . . 12 Cities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Geography . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . 13 IN THE WORKS?. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 WEATHER DATA SOURCES . . . . . . . . . . . . . . . . . . . . . . . . 16 THUNDERSTORM STRUCTURE (registered version only) . . . . . . . . . . 17 Unicell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Squall Line . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Multicell Cluster . . . . . . . . . . . . . . . . . . . . . . . . 17 Multicell Line. . . . . . . . . . . . . . . . . . . . . . . . . . 17 Supercell . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 WEATHER FORECASTING (registered version only). . . . . . . . . . . . 18 Wind. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Coriolis Force. . . . . . . . . . . . . . . . . . . . . . . . . . 19 Air Masses. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Dynamic Effects . . . . . . . . . . . . . . . . . . . . . . . . . 19 Rising Motion . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Troughs and Ridges. . . . . . . . . . . . . . . . . . . . . . . . 19 Long Waves. . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Short Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Subgradient Winds . . . . . . . . . . . . . . . . . . . . . . . . 20 Forecast Discussions. . . . . . . . . . . . . . . . . . . . . . . 20 Numerical Forecasts . . . . . . . . . . . . . . . . . . . . . . . 20 Technical Lingo . . . . . . . . . . . . . . . . . . . . . . . . . 21 ============================================================================ Welcome to the world of advanced forecasting! WeatherGraphix (formerly Weather Pro and RadarScan) is a full color EGA/VGA-graphics program which plots high-resolution weather graphic charts. It gets its information from National Weather Service data that you capture on any database you prefer -- no longer are you tied to a specific system (with extra costs) just to get maps. You use the program offline, at your leisure, saving you time and money. WeatherGraphix is -not- a cute toy. It's a slick tool, and it's about the best one in existence for pilots, amateur weather persons, storm spotters, storm chasers, and just about anyone who wants to have the upper hand on the Weather Channel. It offers some features that are comparable to those seen in weather forecasting centers and on weather briefing terminals used by the major airlines. The high-resolution base map of North America is the big plus. It's plotted in the polar stereographic projection, and on it, you have complete control over zooming and panning! You can even get into the geography database and modify it, say to enhance the coastline, or add highways, county lines, and air routes. Weather Pro offers complete coverage and support for the United States, Canada, and Alaska -- it is guaranteed to work for users living in each of these regions. There is another file, too, which contains modifiable cities and towns you can overlay with a keystroke -- perfect to determine whether Northville Municipal Airfield is getting hit by a storm or just to see if it's raining over at Grandma's place. The radar plotting ability is the major strength of the program. It produces charts that are strikingly similar in form to those received by National Weather Service forecasters over AFOS circuits. You don't get a dinky, vague CGA chart -- you get a full-color, almost broadcast-quality radar composite for the contiguous United States (Canadian radar data is not supported). At your option, WeatherGraphix will overlay maximum tops, bow echoes, hook echoes, line-echo wave patterns, BWERs, WERs, and other significant storm features. It will even outline the exact coordinates of severe squall lines! As you can imagine, it does away with those warped "teletype"-style radar dot maps available on many databases. If you've used one of them, you know how difficult it is to locate a city accurately or plot straight-line routes. WeatherGraphix masters surface analysis on the PC. It adds sky condition, temperature, dewpoint, sea level pressure, and wind data from hourly surface reports in the form of standard plots. You don't get large, oversized plots, which plague many specialized weather graphics maps seen on professional databases. You get a small, meteorologically useful density of data, perfect for examing small-scale (mesoscale) conditions, along with the option to either plot ALL reports or let the computer reduce clutter. You can also instruct WeatherGraphix to plot the surface wind only, without the other data, to get an idea of the surface wind field. You can't beat it for planning a flight or a trip. Fronts and disturbances will stand out perfectly. Rawinsonde data can be imported into WeatherGraphix. From this information you can plot constant pressure charts with raw data, create height contours, make your own customized 500-millibar vorticity maps, and even evaluate shear over a storm threat region! WeatherGraphix decodes FDHI/FDLO upper-air reports, widely used by pilots, to plot upper air wind charts. You choose which level and valid time you want, and WeatherGraphix selects the correct data set. Like the surface chart, it draws a network of standard station plots. The results are sharp. And users who don't have access to rawinsonde data can analyze the FD maps just as if it was rawinsonde data (with some obvious limitations). Compositing is a state-of-the-art word in many forecast offices today. It means being able to overlay radically different types of data on one another, and it's a key concept in the National Weather Service's new AWIPS (Advanced Weather Interactive Processing) computer system. WeatherGraphix brings this power to your desk, and adds ADAP-type diagnostic analysis of all levels. For example, you can plot the color radar chart and then overlay surface data on it, perhaps to find out if that front is driving the storms or not, or what the winds in a rain area are. Then you might want to zoom in really close for a better look at the mesoscale composite, and allow WeatherGraphix to fill in more data in that area. Or you can overlay the upper-level winds on the squall line to see how the storms will be steered. Or check the moisture convergence at the surface to see just how the storms are being fueled. And it's fast. On my Gateway 386/25, the North American base map plots in four seconds. Take a huge 150,000-byte weather data file. Sifting through this mountain of information, WeatherGraphix plots surface observations in 12 seconds. Upper-level wind data takes about 7 seconds. Radar height data plots in 8 to 17 seconds. Radar decoding takes anywhere from 8 to 30 seconds. The catch? You have to get the data yourself. To save time and effort, many terminal programs will let you design a script to automate the process. Where do you get the data? YOU decide! For example, on CompuServe, aviation weather is part of the basic services -- $8 a month, with no connect charges. Pilots can use DUAT and Weathermation, which are free. WeatherGraphix will sink its teeth into almost ANY raw data from ANY database -- if it can't, I'll try to adapt it for that system. Without a doubt, WeatherGraphix is one of the most powerful, flexible tools available to amateur forecasters, pilots, and students. 1. REQUIREMENTS WeatherGraphix requires a PC or 100% compatible with at least EGA (640 x 350 x 16) graphics. VGA (640 x 480 x 16) is preferred, however. A 286 (AT) or higher grade computer is highly recommended for optimal performance. A hard drive will also speed things up somewhat. You will also need 1 meg of empty space, minimum, to install the program in your WeatherGraphix directory, so a hard drive is recommended. The final requirement is a source of weather reports. You wil need either FDHI/FDLO reports, surface aviation reports, SD radar data, and/or rawinsonde (TTAA/TTBB/PPBB) data. The data source should NOT modify the original reports in any way (no "decoded" reports, for example!). CompuServe, AccuWeather, Contel DUAT, and Weathermation are examples of data sources which have been successfully tested with WeatherGraphix. 2. TERMS OF USE There are two versions of WeatherGraphix, a demo version and a registered version. Each have different terms of use. 2.1. Demo Version. If you're on any BBSs, feel free to upload and freely distribute the demo version, WEATHER.ZIP, which is available on CompuServe as WEATHE.ZIP. It is also enclosed on the registered program disk as "WXDEMO.ZIP", and may be uploaded intact. My only restrictions -- you may not tamper with the content of that file in any way, nor can you sell the file for profit or include it as part of another package. 2.2. Registered Version. You may not upload or distribute any portion of the registered version whatsoever. It is protected under Title 17, USC and international copyright laws. Unauthorized distribution of any part of it constitutes copyright infringement. I am involved extensively in meteorology and will quickly be able to track down unauthorized copies of this program. With countless hours invested in this system I will not hesistate to follow up on and take action if I suspect copyright infringement. 2.3. Liability. THE WEATHERGRAPHIX SYSTEM IS PROVIDED WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED. The author makes no claims or representation as to its accuracy, reliability, or fitness for a particular purpose. The author disavows any liability connected with this program and documentation, and the user assumes all risks from the application and use of it. In other words, you use it at your own risk! It would be great if I could guarantee this program to work 100%, but this would quickly make it a full- time project for me. Instead of doing that, I'd rather provide a program that works 99% of the time, for a lower price. If you need guaranteed precision and reliability, I will gladly point you toward the thousand-dollar-plus packages and systems produced for the weather industry by companies such as Kavouras and Alden. Their data invariably goes through highly specialized human and computerized quality control checks that assure you of top-notch accuracy. Although I will try to snuff out all errors and release corrected updates, you should use WeatherGraphix with caution and common sense. This especially goes for you pilots, whose lives depend on the weather -- you already know that you're required to get a formal weather briefing before takeoff. WeatherGraphix, unfortunately, doesn't constitute one. Unformatted weather reports severely test the limitations of any processing method, and since this is a spare-time project for me, I haven't had the time to explore every last data error that could cause this program to malfunction. 2.4. Improvements. If you have any comments, suggestions, or questions, you may send them to the address listed above. For a quicker response, write to me at the computer addresses shown. 3. REGISTERING A COPY (unregistered users only) A registered copy of WeatherGraphix is $45. "Forty five dollars?!" you say. "For that much, I'd better get something good!" Well, here's what you get. 3.1. The Program. You get the full-fledged program, of course. It allows you to zoom and roam around in different regions, giving you a tremendous leap in the number of stations and analysis resolution available to you. See the enclosed file, SAMPLE.GIF, using a graphics viewing program to get a look at what you'll be in for! 3.2. Documentation. You get this documentation file in the form of a desktop published manual. AND you get a guide to weather forecasting and thunderstorms, just in case you're wondering what drives the jet streams or what "short waves" are. 3.3. Improvements. You get a say in what you'd like to see in future updates. This program has constantly been improving due to the suggestions of many die-hard users. 3.4. How to Register. To register, just send a check or money order for $45 to Tim Vasquez at the address listed at the beginning of this manual. Your package will be sent to you first-class U.S. mail (postage is included). 4. OPERATION Here's a brief outline of what it takes to use WeatherGraphix. Once you get familiar with the process, you can build batch and script files which automate the entire process to your own specifications. And with the right software, you can even let your PC dial up and display a new chart every hour -- automatically! 4.1. Capture the data. Before you get the data, turn on your "capture" or "disk log" function to capture the raw radar reports. Reports are stored in two seperate files. Store surface data (surface observations, radar, forecasts, plain language, etc) in DATA.SFC in the WeatherGraphix directory. This name can be changed as will be shown later. You must store rawinsonde and winds aloft information (FDLO/FDHI) in a separate file -- DATA.UPR, which is stored in the WeatherGraphix directory. This filename may also be renamed. The reason this information is stored separately is because upper-air data only changes once every 12 hours, as opposed to hourly for surface and radar data. This will save you time and effort when making multiple captures in the same day. Important! Make sure existing files are deleted first (unless you plan to use old data, for example, the latest upper air file, and you don't plan to add anything to it). Some terminal programs may append data to the end of a file if it already exists, and this WILL eventually cause you problems. So make sure that your "disk log" or "capture" command is configured to destroy or overwrite any existing file. 4.2. Access the data. Using any quality terminal communications program log into your database and capture one or all of the following. It doesn't matter what order the reports are in, as long as they aren't modified. WeatherGraphix will ignore all extraneous text, so you don't need to edit the captured file. Retrieve one or all of the following: 4.2.1. Current radar observations (SD reports). This may take about 1 to 2 minutes at 2400 baud. You can select certain regions only, but your map may be incomplete as a result. On CompuServe, use the command "SD @ALL". On Accu-Data, use the command "RADU * 1". See the data vendor's guide for further help. 4.2.2. Current surface observations (the common airways format). There are over 2000 stations in the United States and Canada, and this amount of data may take 6 minutes at 2400 baud to download. If this is too long, you may just want to select certain states, and a handful of representative stations elsewhere. On CompuServe, use the command "SA @ALL", or "SA @TX,@OK,@LA", etc, to get specific areas. On Accu-Data, use the command "HRU * 1". See the data vendor's guide for further help. Be sure that you get, at the minimum, the latest hourly reports, not just "special" observations. WeatherGraphix does not plot special observations. Weathermation, for example, will ignore a station's hourly if a special observation has been taken recently; you can correct this by specifying a parameter of one-hour's worth of data. 4.2.3. The latest FDLO/FDHI winds aloft data for the United States. This may take about 3 minutes. 4.2.4. The latest rawinsonde reports for North America. These are NOT available on CompuServe, DUAT, Weathermation, etc. They must be RAW reports, not processed or "decoded". An example of usable reports is "UPU 72,74,71" on Accu-Data. Blocks 72xxx and 74xxx are the contiguous United States, 70xxx is Alaska, 71xxx is Canada. You can select whichever blocks are must useful for your needs. Capturing all of North America will take about 10 minutes at 2400 baud. Rawinsonde reports must be stored only in the file "DATA.UPR" in the WeatherGraphix directory. One factor that will affect your data gathering activities is the time. Radar and surface reports are filed at opposite times of the hour, and are stored in "batches". This means that if you're not careful, you could get a potpourri of data times which will reduce the number of usable reports for WeatherGraphix. Radar reports are filed at :25 past the hour and surface observations at :55 past the hour. Accordingly, you should allow for the data to come in. WeatherGraphix checks report times carefully, and will throw out observations that don't conform to a single time. 4.3. Run WeatherGraphix. Exit the telecommunications program, change the current directory to the WeatherGraphix directory, and enter WEATHER to run WeatherGraphix. If you did not save your surface data to DATA.SFC, append the desired filename to the command, for example, WEATHER 08JUN92.22Z . You may also append an upper air file to the surface file if data was not saved to "DATA.UPR", for example "WEATHER 08JUN92.22Z 08JUN92.RAW". But if you specify an upper air file, you must also specify a surface file, even if it's the default file. If you do not have a VGA card (only EGA), or desire an EGA map, append /E to the end of the startup command (for example, enter WEATHER 08JUN92.22Z /E). Normally, WeatherGraphix will be able to sense whether you have EGA, but the /E can be used as a last resort. 5. INSIDE THE PROGRAM Once you run the program, you will see a map of the United States, Mexico, and Canada. Then the program accesses weather data. When it's done, it does not magically display a map. You must tell the computer what you want to see, using the commands listed below. To access the menu, use the cursor keys and the enter key. You can also use hotkeys. You'll notice that each menu selection has a certain letter underlined. If you press this underlined letter on your keyboard, the menu selection will be activated. The bottom title bar contains some useful information. The active surface filename is shown after the "S:", while the active upper-air filename is shown under "U:". WeatherGraphix uses these two separate files since the surface data changes hourly, while the upper-air data is usually current for 12 hours, thus saving headaches in capturing data. The figure after the "M" tells you how much memory is free, in bytes. Anything over 50,000 is more than enough for WeatherGraphix. Always look at the very bottom line when you run the program, because it tells you what the program is doing. WeatherGraphix will never "leave you hanging". Check out this line before you start trying to activate menus. 5.1. Active Level Commands. The leftmost title on the top bar shows the active level in the atmosphere. It is preceded by an "S:", because the hotkey for this menu is always "S" no matter which level is loaded. When you start the program, it shows "SFC", which means any data you plot or analyze will be surface data. If you access rawinsonde data, you can change the level so that it reads "500 MB", "700 MB", etc, which are different atmospheric heights. 5.1.1. DATA PLOT (FILTERED) Plots raw station reports on the map, using standard meteorological "station plots". It shows the conditions at various observing sites across the map. The "filter" feature option checks if two stations are too close together -- if so, only one of the stations will be plotted. This process is called "anti-crowding", and gives you an easy-to-read map at any zoom setting. 5.1.2. DATA PLOT (ALL SITES) Again, this plots raw reports on the map using standard meteorological "station plots". The only difference is that ALL sites are plotted, regardless of how close they are to each other. It could cause your map to become cluttered unless you zoom in closer. However, if you're already zoomed close on a state, you may prefer having the additional stations plotted by using this command. 5.1.3. TEMPERATURES This is a quick option to display the temperatures across the map region. It makes it easy for "non-weather" viewers to see what is happening. 5.1.4. WIND FIELD Plots the surface wind field, as observed at the various meteorological stations. Note that this does not use anti-crowding to reduce clutter. ALL stations will be plotted regardless of settings. You can also get a detailed, gridded wind field by selecting "Analyze, Wind Grid" from the top bar. 5.1.5. CHANGE LEVELS If you have any upper-air data stored in DATA.UPR (or equivalent filename), you can access this information by changing levels. You will be prompted for whether you want to see SFC, 925, 850, 700, 500, 400, 300, 250, 200, 150, or 100 millibar data, which require rawinsonde data to be stored in DATA.UPR. The 925 mb level is approximately 3,000 feet; the 850 mb level is approximately 5,000 feet; the 700 mb level is approximately 10,000 feet; the 500 mb level is approximately 18,000 feet; the 300 mb level is approximately 30,000 feet; and the 200 mb level is approximately 39,000 feet. You may also select FD to access the FDLO/FDHI reports stored in DATA.UPR or its equivalent filename (follow the instructions to select the desired data). Any further data plots or analysis you do will be ONLY for that level -- to get surface analysis again, you will need to "change levels" back to SFC. 5.2. Radar Commands. Radar information is stored in the hourly surface file (DATA.SFC or its equivalent). This data must consist of unformatted SD alphanumeric radar reports. 5.2.1. ECHO COMPOSITE Overlays radar echoes. The echoes are plotted in either squares or bubbles according to the program configuration; bubbles are slightly faster and use less disk space, but squares are more precise. 5.2.2. RADAR HEIGHTS Overlays maximum echo heights, bounded weak echo regions (BWERs), weak echo regions (WERs), line echo wave patterns (LEWPs), bow echoes, hook echoes, and hail indications. LEWP coordinates will be plotted on the map using the color specified for the city overlay. If minimum height criteria is specified in the configuration, then all storm tops below that height will not be plotted. Important! If the map is too cluttered or has too many radar echoes, some radar height data will not be plotted. This is to avoid making the map illegible. 5.2.3. ECHO MOVEMENT Plots movement of various cells. The movement is shown as a feather -- much as with wind barbs, each one represents 10 knots, while a half one represents 5 knots. The feather points toward where the cell is travelling. At this time, only cell movement is plotted -- not area movements. 5.2.4. ERASE RADAR ECHOES This command will remove the radar echoes without disturbing other information on the map. This is done on a color slot basis, so if you configure the color settings so that any text or graphics have the same color as a radar echo, it will be erased, too. Radar height data is not erased. 5.3. Analysis Commands (All Levels) Analysis -- what is it? It is the process of allowing the computer to interpret the data, by plotting lines, gridded data, or outlines. This information is not definitive -- in some cases, you may be able to do a more accurate analysis if you do it by hand. The computer has to contend with bad reports, unusual mathematical fields, and its inherent inability to make inferences from the data, all of which limit its accuracy. You should always overlay the raw data when possible so that you can compare what the computer is seeing to the real atmosphere. WeatherGraphix requires you to have at least several reporting stations in your selected area, since an analysis can't be generated magically. Remember that the fewer the stations, the more unreliable the analysis. Also, the further away from the weather stations you are (such as over the ocean), the more unreliable the analysis. Offshore lows will usually appear to be right on the coast for this reason (since there are no data points in the ocean to place a low). With tighter zooms, the increase in data resolution will give you improved analysis detail in the region selected. 5.3.1. SEA LEVEL PRESSURE (Surface Only) Plots isopleths of sea-level pressure (isobars) in tens and units of a millibar. It is most accurate for tracking highs, lows, and weather systems. Sea-level pressure contains corrections for temperatures at each station, so it is very useful when looking at the big picture. 5.3.2. HEIGHT (Rawinsonde Only) Isopleths lines of equal geopotential height (height contours) of the constant pressure level which is active. This is similar to a "pressure" map of the atmosphere aloft -- low heights are similar to low pressure at that level, while high heights are like high pressure. At 700 mb and above (500 mb, etc), the wind tends to parallel the contours. At the 500 mb level, contours are labelled in hundreds and tens of meters, plus 5000 (e.g. 76 equals 5760 geopotential meters). At 700 mb, contours are in hundreds and tens of meters, plus whatever puts it in the 2500- 3500 range (e.g. 94 equals 2940 meters). At 850 mb, contours are in hundreds and tens of meters, plus 1000 meters (.e.g. 46 equals 1460 meters). At 925 mb, contours are in hundreds and tens of meters (e.g. 76 equals 760 meters). At 1000 mb, contours are in hundreds and tens of meters (e.g. 12 equals 120 meters). 5.3.3. TEMPERATURE Plots isotherms (lines of equal temperature) in degrees Fahrenheit at the surface, or Celsius aloft. 5.3.4. DEWPOINT Plots isodrosotherms (lines of equal surface dewpoint) in degrees Fahrenheit at the surface, or Celsius aloft. Dewpoint temperatures show you most accurately the true amount of water vapor available to weather and storm systems. 5.3.5. DEWPOINT DEPRESSION Analyzes the spread between the surface temperature and surface dewpoint, in degrees Fahrenheit (surface) or degrees Celsius (aloft). This shows you the amount of saturation of the air mass, similar to relative humidity, and can be useful for locating potential fog and cloud areas. 5.3.6. RELATIVE HUMIDITY Analyzes the relative humidity, in percent. Areas of 90 percent or greater are generally prone to fog and stratus clouds. 5.3.7. CONVERGENCE Analyzes the vector convergence of the wind field, using arbitrary units. Blue regions indicate divergent areas, where surface air is spreading apart, and red regions indicate convergent areas, where air is coming together. Convergent areas at the surface often result in upward vertical motion, and are favorable to the development of low cloud decks and precipitation. Divergent areas at 500 mb may sometimes indicate divergence at higher levels (300 mb, etc), which in turn indicates that surface pressure falls and cyclogenesis are possible. 5.3.8. VORTICITY Analyzes the relative horizontal vorticity of the wind field, using arbitrary units. Blue regions indicate negative vorticity (anticyclonic) areas, and red regions indicate positive vorticity (cyclonic) areas. Surface vorticity has some use in finding surface lows -- to determine vertical motion through vorticity advection, you may NOT use surface vorticity. Instead, you need to get rawinsonde data, and analyze the vorticity at 500 mb. You MAY use FDLO/HI data for 18,000 feet, but remember that FD reports are not observed data -- the results may be excessively smoothed over or distorted by the numerical forecast models which create the FD reports. 5.3.9. WIND GRID Displays a uniform gridded wind field across the region, determined by breaking all the wind reports into their X and Y components, filtering the results, and mapping the information to a grid. This is very helpful in visualizing the winds across the area of interest, and can be highly accurate in locating lows and highs (often more accurate than computer-generated isobars). The wind shaft is pointed upwind, i.e. the wind arrow as a whole "points" downwind. Gridpoints with dots and no wind shaft indicate winds are calm or less than 3 knots. A dense grid is provided at the surface, since the resolution can support a detailed grid fiend. However, a light grid is used at levels aloft. The use of dense and light grids is automatic and cannot be changed. 5.4. Analysis Commands (Surface Only) There are more analysis options provided for surface data. Some of these include: 5.4.1. SURFACE MOISTURE CONVERGENCE Analyzes the product of the vector convergence of the wind field and the surface mixing ratio (extracted from dewpoint). In other words, it tells you where "moisture is piling up". Blue areas indicate regions of moisture divergence, and red areas outline moisture convergence zones. It is a very helpful tool in locating regions where severe thunderstorms are favorable, especially when the area moves very slowly. Tornadic storms have often been observed to have a moisture convergence center to their southeast. 5.4.2. ALTIMETER SETTING Analyzes the altimeter setting in tenths and hundredths of an inch. It gives isobars, however they are skewed due to temperature deviations at various stations. Pilots can use it to see the QNH pressures along the route of flight. 5.4.3. WIND CHILL Analyzes the wind chill in degrees Fahrenheit. 5.4.4. HEAT INDEX Analyzes the heat index in degrees Fahrenheit. 5.4.5. WEATHER DEPICTION A weather depiction will give you a chart outlining areas of MVFR (marginal visual flight rules) and IFR (instrument flight rules). MVFR encompasses conditions of ceilings less than 3000 feet and/or visibility less than 5 miles. If a ceiling of less than 1000 feet and/or a visibility of less than 3 miles is present, the spot is considered to be in IFR conditions. A ceiling of less than 500 feet and/or 1 mile is considered LIFR (low instrument flight rules). The floodfill shading of the IFR areas will erase any data underneath. This occurs due to programming limitations. It is suggested that you call up a weather depiction before you add other information. For the non-aviation people, MVFR can be considered low overcast weather, IFR very low overcast, and LIFR bad weather. 5.4.6. PRECIPITATION Outlines areas of rain and snow, based solely on surface weather reports. You can use this to refine the radar display, or substitute for it if it is not available. It also shows the delineation between rain and snow -- where they overlap, a mixed bag of weather is occurring. 5.5. Map Commands. These commands have nothing to do with the data. They are solely for the purpose of moving the map, adjusting the window, and showing you information such as the location of weather stations and cities. Note that unregistered copies of the program are unable to zoom or pan -- they are permanently locked onto the wide- screen United States map. 5.5.1. ZOOM CENTER Centers the map on any station in the WEATHER.STN database. You will be asked for the 3-letter identifier of the station that you want to center on, and then you will be prompted for a map width in miles. 5.5.2. CLEAN MAP Plots a clean basemap without moving or rezooming the image. Cleans the slate, so to speak. This is useful when you have accidentally overlaid an unwanted field on the map. It also cleans the auto-composite slate (to be discussed shortly), erasing memorized dataset choices. 5.5.3. OVERLAY CITIES Overlays cities and towns contained within WEATHER.CTY. The overlay always uses an automatic anti-crowding algorithm to prevent the cities from cluttering each other, so some towns might temporarily disappear on wide zooms. 5.5.4. STATION ID OVERLAY Overlays on the map station identifiers. You will be asked to select whether you want weather stations, upper air stations, airports, or aviation navaids. 5.5.5. CENTER ON UNITED STATES Deselects any zoom settings and starts you out with a national map of the United States. 5.5.6. MANUAL ZOOM Manually zooms in and out of the map. This will help adjust your zoom. 5.5.7. MANUAL PAN Moves east, west, north, or south around the region. It will help adjust your map frame. 5.5.8. OVERLAY BASE MAP Simply overlays the base map without clearing the screen. This is helpful if you can't see state borders for some reason. 5.5.9. OVERLAY HIGHWAYS Overlays highway data on the map, extracted from the WEATHER.PLT or WEATHER.PLX file. 5.5.10. OVERLAY LAT/LONG GRID Overlays the latitude/longitude grid, which is available for offshore locations only. Due to programming limitations, this features is only available to registered copies of V3.2 or later (not to upgrades). 5.5.11. ERASE SCREEN Clears the screen, erasing all map and weather data. 5.6. Other Commands. There are a number of miscellaneous commands available for your use. These include: 5.6.1. REQUEST OBSERVATION This is a powerful tool which lets you request the full surface weather observation from any site in your DATA.SFC (or equivalent) file. You need not have the SFC level active. Just type in the 3-letter identifier (such as "DEN", "BOS", etc), and the bottom window will show you a small clip of the file, containing the requested report. Type in another identifier to see other stations. If you don't have a list of identifiers, simply print the WEATHER.STN file, or overlay Station ID's in the Map menu. When you're done, just hit return and the windows will disappear. 5.6.2. READ RAW DATA Lets you scan through the raw data, in order to read bulletins, raw reports, forecasts, etc. You can also search by keywords (proper upper or lower case is important). 5.6.3. PROGRAM CONFIGURATION This will place you in a menu where you can specify your desired program preferences. They will automatically take effect every time you run WeatherGraphix. Certain options may require you to restart WeatherGraphix before they take effect. Hit the space bar to flip between the various pages in the configuration module. 5.6.4. NEW DATA SET Press this to switch to a different observation time in your data file. For example, if you are currently looking at 1355Z observations and want to see 1755Z reports, enter 18 for a surface time (1755 is actually the 18Z observation). If you leave it blank, the computer will determine the best time to use. You will then be prompted for a radar report time. Use an entry of 22 to get 2235Z reports, or leave blank to let the computer figure it out. You cannot switch data files within the program. 5.6.5. PLOT WATCHES This unique command allows you to see tornado and severe thunderstorm watch boxes that have been issued by the National Severe Storms Forecast Center in Kansas City, Missouri (soon to be Norman, Oklahoma). The program must be able to read the unaltered publicly disseminated watch bulletin, stored in the surface data file, DATA.SFC, or its equivalent. About 99% of watches can be plotted. But WeatherGraphix may be unable to plot the other 1%. This is due to the shortfalls in forcing the computer to "read" the bulletin like a human. For instance, WeatherGraphix looks for keywords such as "HAS ISSUED", "EITHER SIDE", "EAST AND WEST", "FROM", "TO", etc, to find its way around. If the bulletin for some reason is not written correctly, then WeatherGraphix will have trouble processing it. The more important error comes from WeatherGraphix trying to match up the station location names to the listings contained in the WEATHER.LOC master file. As you can imagine, the program is completely at the mercy of whatever the NSSFC forecaster uses for a station location! For instance, if the bulletin says "70 MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTH OF MEMPHIS TENNESSEE", WeatherGraphix will search WEATHER.LOC for any station with "TN" and "Memphis". If WeatherGraphix cannot successfully match a certain city, the box will not be plotted and you will be notified which city can't be located. In many cases, you can remedy this simply by making changes in the WEATHER.LOC file so that the program can read it. Never take the watch box location for granted! If it's important, always verify that the box was plotted correctly by overlaying station identifiers, and viewing the actual text bulletin using the Read Raw Data command. 5.6.6. PLOT CONVECTIVE OUTLOOK If there is a NSSFC (National Severe Storms Forecast Center) convective outlook, WeatherGraphix will plot its coordinates. The bulletin header for this product is ACUS1 KMKC and ACUS2 KMKC. Plotting is done using the data from WEATHER.LOC. 5.6.7. PLOT SIGMET Much in the same way as the convective outlook, WeatherGraphix will look at SIGMETs and plot their locations. Again, plotting stations are referenced against the listing in WEATHER.LOC. 5.6.8. SPECIFY OPTIONAL CHART TITLE This merely lets you specify a title which is plotted in the lower screen box, anytime a map is generated. This is helpful if you are making printouts or displays. WeatherGraphix ignores this information; it is for your use only. 5.7. Quit. Exits the program and returns you to MS-DOS. 6. SURFACE WeatherGraphix plots surface data in internationally standardized station plots. The circle or square over the station is shaded according to the amount of cloud cover. If you see a square, this indicates that the station is a computerized site, and the observation should be taken with a grain of salt. A cross indicates a computerized weather station that doesn't take sky condition reports. A wind shaft extends away INTO the wind, and has feathers -- each long feather indicates 10 knots (11.5 mph), and each short feather indicates 5 knots (6 mph). If there is no feather, a circle is plotted around the station, indicating calm winds. Above and to the left of the circle is the temperature in degrees Fahrenheit. Below the temperature is the dewpoint in degrees Fahrenheit -- this is a direct indicator of the amount of moisture in the air. If you subtract the dewpoint from the temperature, this gives you the dewpoint depression, which is indicative of the relative humidity of the air (the less the dewpoint depression, the greater the relative humidity). Dewpoint per se is an accurate measure of how much energy is available to a weather system, while the dewpoint depression and relative humidity tells how humid the air is and whether fog or low clouds are possible. If weather is occurring, a special data group is inserted between the temperature and dewpoint. It starts out with a number describing the visibility in statute miles (10 = ten miles, 21/2 = two and a half miles, etc). The letters indicate the type of weather that is occurring. They can be decoded as follows: T thunder, R rain, W shower, S snow, A hail, IP ice pellets (sleet), L drizzle, Z freezing precipitation, F fog, H haze, K smoke, BD blowing dust, BN blowing sand, IC ice crystals. If a + is present, this indicates that the preceding weather type is intense, a - indicates it is weak, and nothing indicates moderate. V may be appended to the visibility number, indicating that the visibility is fluctuating (variable). Pressure is located above and to the right of the station circle. What it means depends on whether SLP (sea level pressure) or ALSTG (altimeter setting) is selected. Sea-level pressure is usually the best parameter for general weather browsing. If the configuration file specifies that pressures will be plotted in sea-level pressure, then it will be plotted in tens, hundreds, and units of a millibar. If the group is above "500", stick a 9 before it; if below, stick a 10 before it. Then move the decimal place between the last and second-to-last digit. For example, 983 is 998.3 mb, 046 is 1004.6 mb, and 423 is 1042.3 mb. Sea-level pressure filters out extremes in pressure due to temperature swings and is more accurate for large-scale analysis, but it's only available at 90% of weather stations. If the configuration specifies that altimeter setting will be plotted, pressure will appear in units, tenths, and hundredths of an inch. If the group is above "500", stick a 2 before it; if below, stick a 3 before it. Then move the decimal place to the middle. For example, 983 equals 29.83 inches, 844 is 28.84 inches, and 043 is 30.43 inches. Altimeter setting is a true barometer reading, is available at almost every weather station, and is used by pilots to set altimeters. It fluctuates markedly with temperature. Finally, if a ceiling is present at a station, its height and method of measurement are plotted in the lower right corner of the station. A ceiling is the lowest layer of cloud which occupies 6/10ths or more of the sky (assuming it is visually present behind lower layers). The alphabetical prefix indicates the method of measurement (E-Estimated, M-Measured, B-Balloon, A-Aircraft, W-Vertical Visibility). The remaining digits are the height in hundreds of feet (M31 = measured ceiling 3100 feet, etc). If the station shows broken or overcast skies yet there is no ceiling shown, this means that the layers are thin and no ceiling is present. 7. UPPER AIR Once you select winds aloft from the main menu and enter appropriate data, WeatherGraphix will search the data files for FDLO/FDHI reports. The more reports there are, the more complete the map will be. Similar to the surface wind plots, the shaft points INTO the wind. Each triangular feather means 50 knots (56 mph), each long feather means 10 knots (11.5 mph), and each short one indicates 5 knots (6 mph). This data is not only useful to pilots. The amateur forecaster can look at the patterns to find jet streams (which are closely associated with frontal activity), along with waves in the upper-level winds. When the flow between 20 and 30 thousand feet is predominantly west-to-east, this is called a zonal flow, meaning that systems tend to be dry and move rapidly. However, a flow with numerous dips and rises north and south is called meridional, or low-zonal. Such a pattern suggests considerable transport of energy and moisture northward and destabilizing cold air southward, meaning systems across the country tend to be slow and intense. 8. RADAR When WeatherGraphix plots a radar depiction is plotted, it sifts through the U.S. weather radar network reports and squeezes out all possible data. Its main source of information is from MDR (manually digitized radar) code and polar-coordinate cell reports in the report. Outlined echo areas in the report are not used since they are chunky and often duplicate the MDR data. The decoding process does take a little time; it is this process, not the graphics, that makes it so slow. MDR data is a numerical code which describes intensity levels within a 20-mile Cartesian grid (variable with latitude) overlaid on the radar sweep area. Using MDR data, WeatherGraphix builds the best possible image by painting a "base map" of light precipitation, then discretely painting higher intensities on top. The FAA (Federal Aviation Administration) operates a network of long range air-traffic control radars across the western United States. WeatherGraphix is capable of decoding this data, too. Since a single, small radar echo can straddle a grid border, the MDR code may take more grid boxes than neccessary to define it. This makes radar echoes somewhat larger than they really are, an effect known as "blooming". Although radar operators try to reduce this, it is an inherent drawback of gridding radar echoes and may be reflected by WeatherGraphix. 8.1. Radar Sites. Reporting locations which have contributed data to the echo chart are identified in WeatherGraphix (depending on the configuration setting) using a mark or an abbreviation, precisely centered on the radar site. It will appear as follows: + -- The site is reporting echoes, which have been plotted (the National Meteorological Center doesn't do THIS for you!). NE -- PPINE, Plan Position Indicator No Echoes. The radar is not detecting any echoes. NA -- PPINA, Plan Position Indicator Not Available. The radar is off, but is otherwise working fine. The radar operator may be out doing lunch. OM -- PPIOM, Plan Position Indicator Out for Maintenance. The Maytag man is probably on call. NS -- PPINS, Plan Position Indicator No Significant echoes. Echoes are very small (cover only 20% or less of the grid box) and do not exceed VIP level 1. Sort of a "why bother" code. DE -- PPIDE, Plan Position Indicator Duplicate Echo. Although the site is detecting echoes, a sister radar is reporting them, so no report will be made. Used by the FAA air traffic control centers where the meteorologist sees several radar displays at once and can spot potential duplication of data. 8.2. Echo Intensity. All radars contain VIP (intensity) circuitry which shows the reflective strength of different parts of the echo pattern. Weather pro extracts this from the observation and assigns different colors to the spot. It's important to remember that most radar dishes are elevated about half a degree to eliminate ground clutter, so the depictions always show precipitation at about 1 mile high -- not neccessarily what's occurring at the surface. If a surface station is reporting no weather under a strong intensity level, you can bet it's a matter of time before they get clobbered. Radar intensities are directly proportional to the amount of rainwater contained within the cloud (radar does not detect cloud droplets). At high intensity levels, it can be inferred that a strong convective process is occurring, which often means hail. However, the presence of hail means that less rainfall is occurring than otherwise might be indicated, and it's not even known if the hail is in fact reaching the ground, so you can never really tell exactly what's going on with such intense readings. 8.3. Radar Heights. If heights are desired, WeatherGraphix will sort through the radar reports. It will find significant cloud top heights and plot these on top of the image. It also looks for important radar signatures such as hail, line-echo wave patterns (LEWPs, a dangerous squall line pattern), bounded weak echo regions (BWERs, also known as "vaults" which indicate tornadogenesis), bow echoes, and tornadic hook echoes. It plots the precise location of these features on top of the color map. Where does this data come from? By tilting the radar antenna, the radar operator can construct a cross section of the thunderstorm on a special display (which is never seen outside the radar station). From this, the height of the storm can be determined. The operator encodes the information on the outgoing report. On raw reports and in WeatherGraphix, echo tops are indicated in hundreds of feet MSL (above mean sea level). The tops have a direct relation to the amount of energy available to the storm, but this does not imply that the storm releases it destructively. For example, we might think a 70,000 foot storm would create death and destruction, but weak "popcorn" storms seen in the southern U.S. during the middle of summer sometimes reach these heights without any significant severe weather. As a general guide, this table will indicate the usual content of storms based on echo height, but it's not a book of rules: HEIGHT (ft) TYPICAL DESCRIPTION 20,000 Normal minimum for a rainshower to become a thunderstorm 30,000 Normal height of summertime popcorn thunderstorms 40,000 Strong thunderstorm with heavy rain and isolated severe wx 50,000 Storm often contains hail, heavy rains, high wind 60,000 Normal height of springtime tornadic storms, Great Plains 9. CONFIGURATION The program's configuration values can be modified by selecting the appropriate keystroke from the main menu. This section will list only some selections that will be of interest to you if you're evaluating the program. Data Default File (Surface and Upper Air) Indicates where the program will get data if you type WEATHER to run the program, without a filename. This is normally DATA.SFC and DATA.UPR, but can be modified. You may path out of the WeatherGraphix directory to access the datafile (e.g. C:\DATA\14JUN92.04Z). Startup Zoom Location When you run WeatherGraphix, this indicates on which station the opening map will initially be centered on. This is normally the center of the United States. Startup Zoom Width Specifies the size of the opening map when you initially start WeatherGraphix. Minimum Height to Plot a Height Specifies a cutoff point for plotting Radar Heights. If a value is specified here, no height indicators will be plotted for heights below that level. This can help reduce clutter on your maps. Plot All Surface Weather Stations Leave this set to NO. Plot Radar Echoes During Startup Tells WeatherGraphix whether to auto-plot radar echoes when you execute the program. If you have a slow computer, setting this to "no" will start the program up faster. Plot Radar Heights During Startup Indicates whether the user wants radar heights to be plotted when the program starts up. Again, if you have a slow computer, setting this to "no" will start the program up faster. Plot Echo Squares or Bubbles Bubbles are faster, but squares are more precise. Try both to see what you prefer. Plot Basemap On Startup Slower users may prefer to select "no". This simply determines whether a map is plotted once the program is started. Always Plot User-Defined Geography If "yes" is selected, WeatherGraphix will include customized geography patterns (highways, roads, airways, county lines, etc) on all images. Always Plot User-Defined Cities If "yes" is selected, the program will always include cities and towns from WEATHER.CTY on the map. Plot ALSTG Instead of SLP Tells WeatherGraphix whether to plot altimeter setting or sea-level pressure on the surface data plot. Always Plot Severe Weather From Radar (Temporarily disabled) Overlay Basemap After Plotting Radar This option will force WeatherGraphixfessional to overlay the base map after plotting radar echoes. If you don't like having state borders hidden, this option is for you. If the base map plots slow on your system, this option may not be for you. Auto-Composite Mode If auto-composite mode is activated, whenever you build a weather map (from echoes, heights, surface data, etc), WeatherGraphix will memorize your choices. Whenever you move or zoom the map, the selected data will automatically be plotted on the new map, saving you keystrokes. To erase memorized settings, use the Replot command. The only way to disable auto-composite mode is to revert the configuration setting. Auto-composite mode is not recommended for slower computers, especially for radar echo plots. Auto-composite will not memorize winds-aloft settings or contours. Radar: Plot NE/NA/DE/OM/NS Specifies whether you want radar sites plotted whenever Radar Echo maps are generated. Setting this to "NO" will indicate only radar echoes, suitable for public display. Setting this to "YES" will show the status of all radar sites at the time, indicating how accurate the display is from region to region. Analysis Filter Type The analysis module smooths the mathematical grid before contouring data. Setting this to "MEDIUM" or "HEAVY" gives you smooth contours, but may smooth out important features. Setting this to "OVERRIDDEN" or "LIGHT" will give you ragged contours which are more indicative of conditions in the map area. Temperatures With Winds Aloft Indicates whether you want temperatures plotted with FD winds aloft data. Radar: Plot Distant Echoes Some users prefer not to look at distant echoes, which may be misrepresentative in a national composite. Normally this is set to "YES". Use Detailed Sea-Level Pressure Contours Changes the sea-level pressure contour interval from 4 mb to 2 mb, if "YES". Always Plot Lat/Long Grids on Map If you own a registered copy of WeatherGraphix V3.1A or later, you can activate the lat/long grid by selecting this function. For other users, it has no function. Color Palette Pages Customize the program's colors in these menu pages. You can indicate the color for the background, the base map, city geography, highway geography, the status line, surface plots, etc. The next page lets you customize colors for the radar echo subsystem. 10. CUSTOMIZING THE PROGRAM With a little experience with MS-DOS and a bit of spare time, you can configure WeatherGraphix for your own setup. Whether you run an amateur weather station, fly cross-country, or monitor weather for a company, WeatherGraphix's small details can be tailored to your specifications. 10.1. Batch Files. WeatherGraphix will allow you to use batch files to automate the entire process. You may even automate the system completely, having the computer dial up radar maps every hour, but this requires a memory-resident (TSR) time-delay program -- fortunately there are such programs available within CompuServe forums. Such a program will have to be able to invoke the batch file automatically and initiate appropriate keystrokes to quit the program. If you have a telecommunications program such as Procomm or QModem, you can write scripts which automatically log into your favorite weather database and retrieve the radar data. Then you can link the telecommunications program with WeatherGraphix by using a "batch" file. Batch files simulate keyboard entries at the DOS prompt, so you can use it to invoke the telecommunications program with its script, then run WeatherGraphix immediately. There are many scripts for WeatherGraphix which may be available on CompuServe in the AVSIG forum, Library 1. Unfortunately I can't act as a go-between to get them for you. If you need one, a CompuServe account is rather cheap. Here's an example of a batch file which automates WeatherGraphix using QModem. It's assumed that you already have created a script in QModem using their auto-script feature, and that you save data to C:\WEATHER\DATA.SFC. It's also helpful to go into C:\AUTOEXEC.BAT to make sure that a PATH command is specified to the directory GETWX.BAT resides in -- this way, you can call up the procedure from any directory. Filename: GETWX.BAT ====================== ECHO OFF C: CD \QMODEM QMODEM /S=SCRIPT.SCR C: CD \RADAR WEATHER It's not my purpose to give you a DOS tutorial, so for more information please consult your DOS User's Guide. 10.2. Station Database. The file WEATHER.STN contains a listing of stations used by WeatherGraphix in locating radar and observing sites. It is in a new format which is not compatible with earlier versions of Weather Graphix (Weather Pro and RadarScan). The information in this file is used to plot the observations and radar echoes. You can add or delete stations as you like to modify the density and coverage of reports in desired regions. Be sure to use only an ASCII editor such as MS-DOS EDIT to modify this file. Columns 1-3 contain the three-digit identifier of the observing station. This MUST be in uppercase and must match the exact identifier used in the surface and/or radar reports. Columns 5-9 contain the WMO (World Meteorological Organization) 5-digit identifier for the station. This is only neccessary for processing rawinsonde reports. Columns 11-12 contain the latitude of the station in degrees. Columns 13-14 contain the latitude of the station in minutes. Fill unused columns with zeroes (e.g. encode 8 minutes as "08"). Columns 16-18 contain the longitude of the station in degrees. Remember to fill any unused columns with zeros (e.g. "98" degrees should be "098". Columns 19-20 contain the longitude of the station in minutes. Encode 4 minutes as "04". Columns 22-25 contain the elevation of the station in meters. This is only neccessary for rawinsonde stations. Column 27: If a "C" is present in this column, it indicates that the temperature and dewpoint in the surface weather report will be in degrees Celsius, not Fahrenheit. This usually implies a Canadian station. Column 29: If a "S" is present in this column, it indicates that the station's surface report should be ignored. Perhaps the station's radar report is neccessary, but the surface report is not needed. Columns 31-32 contain the two-letter identifier of the state or province where the station is located. It's for informational use only. Columns 35-75 contain the name of the observing site. Again, it's only for informational use. The program doesn't care what you put here. If you use the "Data Plot, Filtered" command religiously and there is a specific station you have a preference for seeing, simply move it to the first line in the state or to the beginning of the file. Station plots are plotted on a first-in-WEATHER.STN, first-plotted basis, so if you move your station to line 1, you can rest assured it will ALWAYS get plotted. If you wish to make adjustments to a preset zoom window, you can "bogus" this file by inputting a fake weather station, determining the desired latitude and longitude, and specifying it in the configuration file. Be sure that you don't use the identifier of an existing station; QQQ would be a safe one. You may not have more than 900 stations in this file. To make sure you aren't reaching this limit, you can use the MS-DOS editor to see if the line count on the file has exceeded 900. 10.3. Cities. User-defined cities are those which don't correspond to a weather observing site. In this way, you can see precisely if radar echoes, fronts, etc. might be affecting a particular location. You can modify them in WEATHER.CTY. Use any ASCII editor such as MS-DOS EDIT to modify this file. You may not have more than 500 stations in this database. The sample file contains representative stations in the central United States. You can delete or modify this file as much as you like, but do not eliminate it, otherwise you may have problems. The leftmost three columns contain the identifier of the city to be plotted. You can do like I do -- identify towns and cities by an arbitrary two-letter system, although you may use three letters if you prefer (though it will clutter your map a little more). The cities are overlayed in the Map, City Overlay command, from the main menu. Since the program avoids overlaying two neighboring cities atop one another, not all of them will neccessarily plot. The city identifier is located in columns 1-3. The city name is located in columns 6-29 (for your own use only). Columns 30-31 contain the latitude in degrees, and columns 33-34 contain the latitude in minutes. Columns 36-38 contain the longitude in degrees, and columns 40-41 contain the longitude in minutes. If there are any unused numerical columns, fill them with zeroes (i.e. write 79 degrees longitude as '079'). 10.4. Universal Lookup Table. This table, WEATHER.LOC, is of unlimited length, and is used by WeatherGraphix to locate NSSFC watch boxes, sigmets, and convective outlooks. It also indicates navaids and smaller airports which can be overlaid on the map (see the Map ID command). 10.5. Geography. All geography can be modified by registered users. Follow the instructions contained within the file WEATHER.PLT for information on modifying the file. Load the file into an ASCII editor (such as MS-DOS EDIT) to do this. Note -- unregistered users do not have this file. 11. TROUBLESHOOTING WeatherGraphix contains many algorithms which are designed to catch human errors made by those disseminating the radar reports. While it succeeds in dodging most of them, you may find a few that slip through the cracks. So if you see an echo height of 90,000 feet or a hook echo over Idaho, you might want to browse through the raw text file and see what is happening. You can also use a true ASCII editor (such as MS-DOS EDIT) to correct any deficiencies in the data that you see. Or, of course, you can just ignore it. Q. My computer goes berserk when it runs the program. A. Do you have a VGA card? If not, enable the EGA option by appending /E to WEATHER (the startup command). This will force WeatherGraphix into 640 x 350 mode. WeatherGraphix will not run on a CGA computer. Q. The program reads the data file, but no data plots (or some of it plots strangely). What's the deal? A. Be ABSOLUTELY sure that your data source does not reformat the reports in some manner. Also check to make sure that your terminal program is in a standard configuration and does not strip characters/linefeeds or transpose character sets. If you have further trouble send me a note. Q. WeatherGraphix runs strangely and aborts. A. Make sure that you have all WeatherGraphix files residing within the same directory and that you CHANGE DIRECTORY to it before running WEATHER. WeatherGraphix will not run if called from another directory. If this isn't the problem, remove unneeded TSR (memory resident) programs as Wx Pro requires a considerable amount of the 640K memory space normally available -- look into using a memory manager program. Q. Why do the echo squares look so jagged and crooked? A. This is how they are mapped -- you're not seeing an error! When looking at the national map, the Cartesian coordinate grid that the squares use tends to be slightly rotated from the map grid. This gives it the weird appearance. Try centering the map over the east coast, and you'll see the MDR grid much more easily. Q. WeatherGraphix doesn't plot any data or some plots are clearly erroneous. A. BE SURE that your data source and capture utility does not "tamper" with the content of the raw reports. Even something as simple as stripping the equal signs (end of report markers) off the ends of the observations or adding extra characters will cause problems with the program. It would be nice if the program had pure "fuzzy logic" to handle these situations, but such is not the case. Fortunately, I haven't seen any data sources yet which do this. If you do encounter problems, contact me, or write yourself a utility which will preprocess the raw data. If you have found the offending station and it is clearly not a one-time coding error, send me an exact copy of it and I will try to adjust the program to handle it. Q. My customized cities and geography doesn't plot. A. You've either not inputted the data correctly, or you're using a non-true ASCII editor. If you're in doubt, ALWAYS use the MS-DOS EDIT command. If you've already messed up your file, you will need to delete all your entries to strip out the invisible control codes and et cetera. Q. How can I send the chart to my printer? A. There are so many printer models and "printing languages" out nowadays that I decided to wait on any built-in print feature. You're much better off using a TSR (memory resident) program which you can load before running WeatherGraphix. When you press a certain key, such a program will dump the screen image to the printer. Try the MS-DOS GRAPHICS command (read about it in your user's manual), and if this doesn't work suitably, access one from many available on CompuServe. Q. The chart contains too much data! A. If you store, say, 1935Z data in a file, ensure that there is no 1935Z data there from another day. WeatherGraphix cannot tell the two reports apart, and you may get some strange looking maps. You can avoid this by setting up your telecommunications program to destroy any existing capture file before opening one with the same name. Q. Why is the "system time" printed on the chart and not the date of the data? A. WeatherGraphix has no way of knowing whether the data is current or historical since this information isn't contained in the file, and the file date can be ambiguous. So it can't really put a date on the chart for sure. But the computer's clock date is listed on the map to help you out in case you make printouts and need to refer to them later. Q. Tell me about the precision of WeatherGraphix. A. The image is only as accurate as the raw data and technical limitations of the weather radar network and of WeatherGraphix's interpretation scheme. However, WeatherGraphix uses precision in handling the data. All coordinates are transformed mathematically through the polar stereographic projection formula, so placement error is nominal and is subject to the precision of the data. Q. Are the radar echoes located accurately? A. The national MDR grid is based on the LFM-I grid, the same one used by the National Meteorological Center's Cray supercomputers. Unfortunately, I don't have their mathematical formula for translating Cartesian MDR coordinates to lat/long. I've tested some of my own formulas -- they come close but don't meet my standards of precision. Therefore, all echoes are vector-mapped from the radar site using MM as the center location without any gridbox offset. Accordingly, the vector direction is adjusted to account for the MDR-north declination across the United States. Overall, the maximum position error of all echoes relative to the real-world is subject to the limitations of the MDR grid (about 20 nautical miles), plus the deviation of vector-mapping instead of using a mathematical MDR grid (about 10 more miles). It is fairly accurate, and the method interestingly removes much of the "blockiness" from the map. Q. Do you foresee any peace in Yugoslavia? What about the Middle East? A. I thought were talking about weather here! 12. IN THE WORKS? The most immediate ideas for near-term improvements include SKEW-T soundings, hodographs, vertical cross sections, and isentropic analysis. One idea considered for WeatherGraphix includes time-lapse animation. This is very graphics-intensive and I'll probably have to obtain some machine-code routines to do this. It's going to take work. Another feature that I hope to add is automatic data-source dialing. This is something I could even use myself, but writing routines to control telecommunications ports has proven more complicated than I thought. Besides, you can imagine the complications in the different data access protocols used by the countless weather databases in existence today. The purpose of WeatherGraphix was to let you use data from ANY source -- automatic source dialing would be a step away from this goal. You might also expect improvements in the surface and upper air plotting. Maybe vectors and components, too, for you pilots. I'll be looking at compositing of satellite data (with zooms, moves, etc). The only question here is "will the typical user really access all this stuff"? Also being considered are enhancements to plot AIRMETS, SIGMETS, and watches and warnings. Thanks to CompuServe users Robert Kelsoe, Dick Zeitlin, and Scott Dyer for beta testing the basic version of WeatherGraphixfessional. Thanks to Debi Iacovelli for reviewing the documentation, and to Mark Hayes for compiling the WEATHER.LOC list. A special thanks to Patrick Rudolph for his extensive testing and suggestion for the title of "WeatherGraphix". ......................................................................... Extra WEATHER DATA SOURCES There are many ways that you can access data for WeatherGraphix. CompuServe ----- This is one of the largest consumer databases in existence. It offers news, reference services, special interest forums, software download libraries, and the list goes on. In terms of weather, it offers a respectable variety of weather information, allowing you to access all types of National Weather Service data, except for National Meteorological Center products and rawinsonde/synoptic reports. It offers raw surface reports for the United States and Canada, radar reports, FDLO/HI winds aloft, forecast discussions (not listed, but accessible if you use the FE command within the weather section), and many other products. If you subscribe to CompuServe and have the Basic Service plan (which charges you a slightly higher monthly minimum), you get the entire weather service for $9 a month, free of connect time in most larger towns and cities. It's a bargain that should be looked into, although the service has been occasionally plagued by slow response time and nonavailability during peak weather periods. You can also contact me on CompuServe through EMail 71611,2267, or better yet, chat with me on AVSIG (Aviation Forum), Section 1 (Weather), about the program. For more information, call (800) 848-8199 or obtain a Membership package at any software store. Contel DUAT ---- The DUAT weather service is a government-contracted system for pilots which is famous in aviation circles since it is free and accessable through an 800 number. It is a very good data service, but pilots and users have asked me if there are any shortcuts for downloading the entire United States. Unfortunately, there are none. You should develop a script in your telecommunications program to access the desired data, or obtain one from the AVSIG forum, Library 1, on CompuServe, or in the Genie Science-Weather Bulletin Board. As of April 1993, there have been indications that DUAT may be axed due to budget cuts. Stay tuned. Contel DUAT is accessed by modem at (800) 767-9989. DTC DUAT ------- This is another contractor's (Data Transformation Company's) version of DUAT. It can be accessed by modem at (800) 245-3828. Weathermation ------- Pilots in Wisconsin can access an open weather system at 1200 baud. This system is run by the Wisconsin Department of Transportation. Since there are only a few nodes at each site, Weathermation should not be used except by pilots. One number is (608) 326-6076. GEnie ---------- This database offers no information for WeatherPro, however, there is a large group of weather hobbyists running a bulletin board, along with WeatherGraphix support. My address on GEnie is T.VASQUEZ1. Genie costs $4.95 per month, as long as you don't download files or access during the daytime (at which time a higher rate takes effect). To subscribe, call modem (800) 638-8369, half-duplex, and upon connection, type HHH. At the U# prompt, enter XTX99410,GENIE, and hit return. Call (800) 638-9636 voice for more information. Accu-Data ------ Among the most respectable "complete" weather systems is Accu-Data, run by Accu-Weather of State College, Pennsylvania. It gives access to every weather product imaginable. The hobbyist rate runs about $16 per hour during off-peak hours (long distance call required). Call (814) 234-9601 x 400, or (814) 237-0309 for more information. Weather Network, Inc. ---- I haven't personally tried this system, so I can't say what it offers. It is a "complete weather system". Their vital stats: 568 Manzanita Ave., Suite 1, Chico, CA 95926. (916) 893-0308. WeatherGraphix has been modified to accept their surface data.