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6/24/75 AC 150/5300-4B Appendix 3 APPENDIX 3. WEATHER DATA SOURCE AND ANALYSIS 1. PROCEDURE. When an airport is needed in a particular locale, one of the first steps the airport designer must take is to analyze recorded wind observations for the location. Existing National Oceanic and Atmospheric Administration (NOAA) publications should be researched to determine if a satisfactory wind data summary has been published. Assistance can be obtained from any NOAA Weather Bureau Office or from the NOAA State Climatologist. 0f those now available, the 10-year summary (Climatography of the United States, Series No. 82, Summary of Hourly Observations) is the most useful in airport planning and design since it gives the best indication of expected wind conditions at a given site. The most complete information regarding the availability of wind data can be obtained by contacting the National Weather Records Center, Environmental Data Service, Federal Building, Asheville, North Carolina 28801. a. Where wind data for a specific location are not available, the data from two or more of the nearest recording stations should be ex- amined. It must be kept in mind that terrain (lakes, river basins, and hills) surrounding a site can considerably influence the wind direction and speed. The advice of a meteorological consultant should be sought in selecting these surrounding stations. b. If a 10-year summary cannot be obtained, then some lesser period of record can be used; however, 3 years of record of hourly observa- tions should be considered as the minimum upon which runway orientation is based. This recommendation is made as a result of a study of wind records across the country, which showed that a significant difference can exist between the wind coverages obtained from a 10-year summary and from a 3-year summary. c. Where no recorded data are available either for the specific location or from recording stations near enough to be significant, an evaluation should be made of the best local information. If local information does not firmly establish a wind pattern, it is desirable to collect wind data at the site. Data collected for a period of even 1 year can be useful in conjunction with local information in the determination of runway orientation. However, great care must be taken not to allow such limited data to over- ride other influencing factors. Where only 1 year of wind data is available and local judgment is the basis on which orientation is determined, only one runway should be constructed until at least 3 years of observational data can be obtained. d. Figure 1 is an example of an NOAA Environmental Data Service tabula- tion of wind direction versus wind speed. When the summary to be used in the wind analysis has been obtained, transfer the appro- priate data expressed in percentage to the wind rose diagram. Figure 2 is an explanation of the format and its related codes. Par 1 Page 1