Caveats
All that can be expected of any decision maker is that he take good information and apply it wisely to the problem at hand. Long-range weather prediction is inherently difficult. The best that an event organizer can do is to take a careful look at past weather and assume that the future will reasonably resemble that which has gone before. Event organizers must pay careful attention to local weather forecasts as the event time approaches. It is always possible that freakish conditions will occur at the time of the competition, and action may need to be taken emergently to protect the athletes. With proper planning, such re-scheduling of events will rarely be needed.
How these charts were made
.The Heat Index charts provided by the Zunis Foundation are custom-built using the best available weather data and modeling techniques.
Weather data has been obtained from the Solar and Meteorological Surface Observation Network 1961-1990 (SAMSON), a database published in 1993 by the US Federal Agencies NOAA and NREL. It is based on hourly observations from 241 weather stations in the US, Puerto Rico and Guam and contains more than 100 million weather observations.
Information for an individual city is extracted from the SAMSON database and downloaded to an Excel spreadsheet as a 162,960 cell data set. (Each cell contains one piece of information.) This information undergoes a number of extraction and calculation processes through a series of arrays containing a total of 35,280 cells. Heat Index calculations are performed using a 16-element multiple regression analysis equation which models the table published by R.G. Steadman in 1979, the table which has been used for nearly 20 years by the US National Weather Service as the basis for its heat advisories.(The Heat Index is a number derived from the air temperature and the relative humidity to reflect how hot a given set of conditions "feel" to a person who is in them.)
Finally, the information is converted into Excel charts. Each chart displays the heat index values for a single city for a single hour for an entire year, with sampling at 2-week intervals. An entire "set" of charts for a single city is made up of 8 separate charts, one chart each for 6 a.m., 8 a.m., 10 a.m., 12 noon, 2 p.m., 4 p.m., 6 p.m. and 8 p.m.
Due to space limitations imposed by the cost of Internet publishing, charts for just 101 US cities are available at this Web site. We at the Zunis Foundation have charts for an additional 140 cities, 8 hours per city, available for a small fee upon request. These Chart Store charts are larger than those published at this Web site, and they also contain a third measure, "Lowest Heat Index," which was omitted in the Web site charts due to space limits.
We are very proud of the quality of these Heat Index Charts, and we hope that visitors to this site will inspect the chart of a city near home.