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AC 00-6A

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AVIATION" WEATH ER

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AC 00-6A

For Pil sand Flight perations Personnel

Revised 1975

DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION
FI ight Standards Service

DEPARTMENT OF COMMERCE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Weather Service

Washington, D.C. Reprinted by

asaPUBLICATIONS

Editoria 1 Note: Figures 137 through 139 and 142 on pages 160, 161, and 165 have been rearranged to align with their proper legends. Corresponding corrections have been made in the Contents, page XII.

Editorial Note:

(9/82)

Figures 137 through 139 on pages 160 and 161 have been rearranged in order to flow in proper sequence with the text. Corresponding corrections have been made inthe Contents, page XII.

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402

Preface
AVIATION WEATHER is published jointly by the FAA Flight Standards Service and the National Weather Service (NWS). The publication began in 1943 as CAA Bulletin No. 25, "Meteorology for Pilots," which at the time contained weather knowledge consideredessential for most pilots. But as aircraft flew farther, faster, and higher and as meteorological knowledge grew, the bulletin became obsolete. It was revised in 1954 as "Pilots' Weather Handbook" and again in 1965 under its present title. All these former editions suffered from one common problem. They dealt in part with weather services which change continually in keeping with current techniques andservice demands. Therefore, each edition became somewhat outdated almost as soon as published; and its obsolescence grew throughout the period it remained in print. To alleviate this problem, the new authors have completely rewritten this edition streamlining it into a clear, concise, and· readable book and omitting all reference to specific weather services. Thus, the text will remain valid andadequate for many years. A companion manual, AVIATION WEATHER SERVICES, Advisory Circular 00-45, supplements AVIATION WEATHER. This supplement (AC 00-45) periodically is updated to reflect changes brought about by latest techniques, capabilities, and service demands. It explains current weather services and the formats and uses of weather charts and printed weather messages. The two manuals are soldseparately; so at a nominal cost, a pilot can purchase a copy of the supplement (AC 00-45) periodically and keep current in aviation weather services. C. Hugh Snyder, National Weather Service Coordinator and Training Consultant at the FAA Academy, directed the preparation of AVIATION WEATHER and AVIATION WEATHER SERVICES. He and his assistant, John W. Zimmerman, Jr., did much of the writing andedited the final manuscripts. Recognition is given to these meteorologists on the NWS Coordinator's staff who helped write the original manuscript, organize the contents, and plan illustrations: Milton Lee Harrison, Edward A. Jessup, Joe L. Kendall, and Richard A. Mitchem. Beatrice Emery deserves special recognition for her relentless effort in typing, retyping, proofing, correcting, and assemblingpage after page of manuscript. Many other offices and individuals have contributed to the preparation, editing, and publication of the two volumes.

III

Contents
Page Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III Introduction ......................................................... XIII PART I....