AVIATION WEATHER OBSERVATIONS for Supplementary Aviation

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  • NATIONAL WEATHER SERVICE OBSERVING HANDBOOK NO. 8

    AVIATION WEATHER OBSERVATIONS for Supplementary Aviation Weather

    Reporting Stations (SAWRS)

    MANUAL OBSERVATIONS OCTOBER 1996

    U.S. DEPARTMENT OF COMMERCE Mickey Kantor, Secretary

    National Oceanic and Atmospheric Administration

    Dr. D. James Baker, Under Secretary and Administrator

    National Weather Service Dr. Elbert W. Friday, Jr., Assistant Administrator

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    PREFACE

    This handbook was prepared by the the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service, to complement the instructions in Federal Meteorological Handbook No. 1 (FMH-1), Surface Weather Observations and Reports. This handbook is intended for use at Supplementary Aviation Weather Reporting Stations (SAWRS). No other stations are authorized to use this handbook.

    RECORD OF CHANGES

    Change No.

    Effective Date Initials

    DateEntered Remarks

    When you enter a change in this handbook, make a notation on this page. Changes are indicated by a vertical line ( ) in the outside margin adjacent to the data affected. See the example to the right of this paragraph.

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    TABLE OF CONTENTS CHAPTER 1 - INTRODUCTION.................................................................................................. 1-1 1.1 Purpose......................................................................................................................................... 1-1 1.2 Observational Procedures ............................................................................................................ 1-1 1.3 Designated Stations...................................................................................................................... 1-1 1.4 Applicability of Standards ........................................................................................................... 1-1 1.5 Format of Manual Observations .................................................................................................. 1-1 1.6 Changes to Manual Observations Handbook............................................................................... 1-2 1.7 Maintaining Manual Observations Handbook ............................................................................. 1-2 1.8 Unforeseen Requirements............................................................................................................ 1-2 1.9 Certification of Observers............................................................................................................ 1-2 CHAPTER 2 - GENERAL PROCEDURES ................................................................................. 2-1 2.1 Introduction.................................................................................................................................. 2-1 2.2 Surface Aviation Weather Observing Stations ............................................................................ 2-1 2.3 The Weather Observer ................................................................................................................. 2-1 2.3.1 Certification of Observers................................................................................................... 2-1 2.3.2 Observer Responsibility...................................................................................................... 2-1 2.4 Observation Form ........................................................................................................................ 2-2 2.4.1 Disposition of MF1M-10C Originals.................................................................................. 2-2 2.4.2 Retention of MF1M-10C Carbon Copies ........................................................................... 2-2 2.5 Definitions.................................................................................................................................... 2-2 2.5.1 Coordinated Universal Time (UTC) ................................................................................... 2-2 2.5.2 Local Standard Time (LST) ................................................................................................ 2-2 2.5.3 Standard Time of Observation............................................................................................ 2-2 2.5.4 Actual Time of Observation................................................................................................ 2-2 2.5.5 Aircraft Mishap................................................................................................................... 2-2 2.5.6 Surface Observation............................................................................................................ 2-2 2.5.7 Unofficial Weather Reports ................................................................................................ 2-3 2.6 Time ............................................................................................................................................. 2-3 2.6.1 Time Standards ................................................................................................................... 2-3 2.6.2 Accuracy of Time in Observations ..................................................................................... 2-3 2.7 Observing Practices ..................................................................................................................... 2-3 2.7.1 Order of Observing ............................................................................................................. 2-3

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    2.7.2 Recency of Observed Elements .......................................................................................... 2-3 2.7.3 Brightness Adaption............................................................................................................ 2-4 2.7.4 Rounding Figures................................................................................................................ 2-4 2.8 Aviation Weather Observations................................................................................................... 2-4 2.8.1 Aviation Routine Weather Report ...................................................................................... 2-4 2.8.2 Routine (METAR) Weather Observations.......................................................................... 2-4 2.8.3 Special Observations........................................................................................................... 2-4 2.8.3.1 SPECI Observations Upon Resumption of Observing Function ............................ 2-6 2.8.3.2 Single-element SPECI Observations ...................................................................... 2-6 CHAPTER 3 - WIND ...................................................................................................................... 3-1 3.1 Introduction.................................................................................................................................. 3-1 3.2 Definitions.................................................................................................................................... 3-1 3.2.1 Wind Direction.................................................................................................................... 3-1 3.2.2 Wind Speed......................................................................................................................... 3-1 3.2.3 Gusts ................................................................................................................................... 3-1 3.2.4 Variable Wind Direction..................................................................................................... 3-1 3.2.5 Wind Shift ........................................................................................................................... 3-1 3.3 Observing, Determining, and Reporting Procedures ................................................................... 3-1 3.3.1 Wind Direction.................................................................................................................... 3-1 3.3.2 Variable Wind Direction..................................................................................................... 3-2 3.3.3 Estimating Wind Direction ................................................................................................. 3-2 3.3.4 Wind Speed......................................................................................................................... 3-2 3.3.5 Estimating Wind Speed....................................................................................................... 3-3 3.3.6 Wind Gust ........................................................................................................................... 3-3 3.3.7 Wind Shifts ......................................................................................................................... 3-4 3.3.8 Calm Wind .......................................................................................................................... 3-4 3.4 Conversion of True and Magnetic Winds.................................................................................... 3-4 3.5 Priority of Instruments ................................................................................................................. 3-5 CHAPTER 4 - VISIBILITY ........................................................................................................... 4-1 4.1 Introduction.................................................................................................................................. 4-1 4.2 Definitions.....................