Weather Server
Frequently asked questions

Images not updating (especially satellite images)?

• In most cases, it is the browser you are using.  Netscape and IE cache images so you don't have to reload them every time you access a page.  The problem is the image on the web server could change and the browser will display the cached image instead.  To update the image, hit the Reload button on the browser.  Sometimes Netscape doesn't reload even when the reload button is hit.   Try shift-Reload in these cases.
• The scripts that update the images run continuously 7 days a week, 24 hours a day.  The process is very automated but in some remote cases, data won't get updated or the script runs just as new data is coming in.  Timing can be critical.   Check again in a few minutes or an hour and see if the images have updated. If this persists, notify me.
• Even though the GIF generation process is highly automated, we have to rely on timely receipt of data from the National Weather Service. From time to time, data is not delivered on time or is incomplete.  The GIF generator will not update the images in those cases.

Image quality is poor (worse than Purdue)?

• As a part of the reconfiguration of the web server, the GIF images have been placed in HTML pages.  This is to set up the site for advertising and to allow for better navigation of the site.  On 8 bit (256 color) displays (which is the default for most systems) this causes a problem with browsers like Netscape.   Netscape will often display a GIF image with its requisite colors but when the image is embedded in an HTML page, it dithers the image making it look fuzzy or of poor quality.  There are a few ways to solve the problem:
  • Change the color depth of your display from 8 bit to 16 or 24 (16 million colors, recommended) bit.  This will eliminate the dithering and you might find the image looks even better than at Purdue.
  • View the image outside the HTML page.  I know this is an extra step but it should clear up the image problem.  In Netscape you can do this by moving the cursor over the image and hitting "view image" from the right mouse button menu.  In IE, drag the image into the "address" box and this will load the image directly from cache. 
  • AOL Users: AOL uses a compression algorithm on the satellite images which greatly reduces the image quality.  You need to set image compression to No.

Where does the data come from?

• At this time, the data used for most of the images on the site are from the National Weather Service via the NOAAPORT satellite feed.  Other data sources include Colorado State's hurricane archive and USGS elevation data.

How do I print images with a white background?

• Printing the images with black backgrounds can be rather nasty looking, not to mention consuming tons of toner.  I have included a "Inv" link on many of the pages in order to solve this problem.  This link goes to an equivalent image where the background is white.

Why don't the images print properly?

• In some cases, the large images are clipped when you print them out.   This is more of a problem with IE than Netscape.  IE does tend to clip off the right side of the image.  I have tried making the margins smaller to reveal more of the image.  Netscape tends to size the image to fit the page.  In some cases, this will distort the image.

Why doesn't the interactive forecast work?

• The problem is that the web server consumes much of  the system resources under heavy loads such as during the middle of the day. This prevents processes needed to run the interactive forecast from running.  If this happens, try again in a few minutes.   If it continues to happen, try again after peak hours (such as during the evening or early morning).

Where is the old interactive text forecast?

• The old interactive text forecast with the 24 hour listing of data plus text forecasts and sunrise/sunset data was retired from active service.  This is because it consumed too much CPU time to produce.  For most users, this page was too technical and thus the simpler forecast page was created.  For those who still wish to use the old text forecast page, enter something like the following: http://weather.unisys.com/foredat.cgi/Chicago.  

Forecast maps blank?

• The timing of when the model data arrives and the running of the scripts is critical.   If the models come in late or only a partial run is transmitted, this can result in blank frames in the forecast maps. 

Forecast maps corrupted?

• In some cases, the reception of data can be corrupted.  If this happens, the plot may be corrupted. In many cases, most of the product is good so WXP will display as much as it can before determining the rest of the grid is bad.

What does the Text Forecast script (foredat.cgi) return in terms of data?

• When you click on the interactive map, it returns the following information:
  • Sunrise and Sunset data plus twilight data.
  • The last several hours of surface observations from the city
  • The latest Nowcast.  Nowcast are only available during inclimate weather
  • The latest Zone Forecast.  Zone Forecasts are based roughly on small subsets of counties.
  • The latest State Forecast.  This is a general forecast for the entire state.   The last portion of the State Forecast is the 3-5 day extended forecast

What are the categories on the Surface Observations?

• T = Temperature in Fahrenheit
• TD = Dewpoint in Fahrenheit
• DIR = Direction the winds are coming from in degrees,
  N = 0, E = 90, S = 180, W = 270
• SPD = Wind speed in knots (roughly MPH)
• ALT = Altimeter setting in inches of mercury 002 = 30.02", 984 = 29.84"
  Altimeter setting is the correction of surface pressure to sea level using standard atmospheric temperatures and lapse rates. It is subtally different than the sea level pressure which is derived from using current temperatures and a lapse rate defined for each station.
• SLP = Sea level pressure in millibars 014 = 1001.4mb, 976 = 997.6mb
• VIS = Horizontal visibility in miles
• CEIL = Cloud ceiling in 100s of feet 15 = 1500 feet, 250 = 25,000 feet
  COV = Cloud coverage CLR = clear, SCT = scattered,
  BKN = broken, OVC = overcast, X = obscured
• WX = Present weather
  • T .. Thunder
  • Z .. Freezing
    Precip type
  • R .. Rain
  • L .. Drizzle or mist
  • S .. Snow
  • A .. Hail
  • IP .. Ice Pellets
    Obscurations
  • F .. Fog
  • H .. Haze (visibility reduced but greater than 3 miles)
    Intensity
  • W .. Showers (intermittent precipitation not continuous)
  • + .. Heavy
  • none .. Moderate
  • - .. Light
    
    Examples
    RW- .. Light Rain Showers
    TRW+ .. Heavy or Severe Thunderstorm
• EXT = Max/min temperature
• PR6 = 6 hour precipitation in inches
• PR24 = 24 hour precipitation in inches
• SC = Snow cover in inches

Surface map plots... what is all that data?

• The circle represents cloud cover. The open (black) circles represent clear skies and filled circles represent cloudy skies. Varying degrees of fill represent how much cloud cover there is. The line coming out of the circle is called a wind barb. This represents the wind direction and speed. The line points into the wind (the direction the wind is coming from) and the number of barbs determine the wind speed in 10s of knots (roughly MPH). A small barb is 5 knots. For more information, check the details on the surface map.

Black background for maps, I can't print them?

• There is a reason for the black backgrounds:

  On all displays, black is the natural background color. Until recently (with Macs and Windows machines) black was a default for all graphics backgrounds. Macs and Windows use the "I am like a piece of paper" principle.

  Here is the problem. Many displays don't have perfect color convergence. When the color convergence is bad, white backgrounds tend to bleed over and produce fuzzy displays. On the other end, using red and green as primary colors in plots on black backgrounds prevent this bleed over from occurring. This is why most of my plots use red and green.  Add to this that a white background washes out the colors on the plots so distinguishing various colors is more difficult.

  To solve the problem, I have created several inverted images which are available on the individual data pages such as the Surface Data Page.   The inverted images are marked with the following icon: or Inv link on the GIF image pages.

© Unisys 1998 
For more information on this server, contact Dan Vietor at devo@ks.unisys.com
Last modified August 13, 1998