Antigua and Barbuda Meteorological Services Guide to Surface Weather Observations First Edition August 2018 First Edition, August 2018 Forward The contents of this guide prescribes the standard procedures of the Antigua and Barbuda Meteorological Services (ABMS) for observing, recording and reporting weather conditions. It has been prepared in accordance with internationally recommended procedures as established by the World Meteorological Organization (WMO) and the International Civil Aviation Organization (ICAO). The practices and procedures in this document apply to all ABMS observering personnel who provide weather observation services. Weather observer personnel are required to apply the provision of this guide as it pertains to their observational responsibilities. Observers are expected to exercise experienced judgment when encountering situations not covered by this guide. This is a living document and will be revised at intervals to take account of changes in regulations, feedback from the industry and recognised best practices. Inquiries on the content of this guide should be directed to the management of the ABMS through appropriate channels. Guide to Surface Weather Observations Page | 1 First Edition, August 2018 Record of Revisions Section Revision description Guide to Surface Weather Observations Page | 2 First Edition, August 2018 Record of Amendments This document will be kept under continual review to ensure its relevance to the Quality Management System Amendments No. Date Entered Entered by Approved August 2018, initial release S. Brown D. Destin Guide to Surface Weather Observations Page | 3 First Edition, August 2018 Table of Contents Forward .............................................................................................................................................1 Record of Revisions ............................................................................................................................2 Record of Amendments......................................................................................................................3 Table of Contents ...............................................................................................................................4 Introduction – Meteorological Observations ..................................................................................... 10 Part A .............................................................................................................................................. 14 General Observing Procedures ......................................................................................................... 14 Chapter 1: Accreditation and Competence of Observers ................................................................ 15 1.1 General ............................................................................................................................... 15 1.2 Certification ........................................................................................................................ 15 1.3 On the Job Training ............................................................................................................. 15 1.4 Duties ................................................................................................................................. 16 1.5 Priority of Duties ................................................................................................................. 16 Chapter 2: Observing Practices ..................................................................................................... 18 2.1 General ............................................................................................................................... 18 2.2 Types of Observations ......................................................................................................... 18 2.3 Methods of Observations .................................................................................................... 18 2.4 Order of Observing .............................................................................................................. 19 2.5 Recency of Observed Elements ............................................................................................ 19 2.6 Dark Adaptation.................................................................................................................. 19 2.7 Weather Not Observed ....................................................................................................... 19 2.8 Standard Time of Observation ............................................................................................. 19 2.9 Surface Observations .......................................................................................................... 19 2.10 Local Standard Time .......................................................................................................... 20 2.11 Quality Control of Observations ......................................................................................... 20 2.12 Distribution of Reports ...................................................................................................... 21 2.13 Record Retention .............................................................................................................. 21 2.14 Meteorological Instruments .............................................................................................. 21 2.15 Basic Forms of Instruments ................................................................................................ 21 2.16 Quality Control of Instruments and Sensors ....................................................................... 22 2.17 Sensor Evaluations ............................................................................................................ 22 Guide to Surface Weather Observations Page | 4 First Edition, August 2018 Chapter 3: Observing Weather Elements ....................................................................................... 23 3.1 General ............................................................................................................................... 23 3.2 Wind................................................................................................................................... 23 3.3 Direction ............................................................................................................................. 23 3.4 Speed ................................................................................................................................. 23 3.5 Character ............................................................................................................................ 23 3.6 Gusts .................................................................................................................................. 23 3.7 Squall ................................................................................................................................. 24 3.8 Estimation of Wind ............................................................................................................. 24 Chapter: 4 Sky .............................................................................................................................. 25 4.1 Sky Condition ...................................................................................................................... 25 4.2 Definitions .......................................................................................................................... 25 4.3 Layer Determination ........................................................................................................... 25 4.4 Layer Identification ............................................................................................................. 26 4.5 Height ................................................................................................................................. 27 4.6 Methods of Determining Heights of Layers .......................................................................... 27 Chapter 5: Visibility ...................................................................................................................... 29 5.1 General ............................................................................................................................... 29 5.2 Guides to Determining Visibility .......................................................................................... 29 Chapter 6: Atmospheric Phenomena ............................................................................................. 30 6.1 General ............................................................................................................................... 30 6.2 Precipitation ....................................................................................................................... 30 6.3 Liquid Precipitation ............................................................................................................. 30 6.4 Other Hydro-meteorological Deposits .................................................................................. 32 6.5 Thunderstorm (TS) .............................................................................................................. 32 6.6 Funnel Cloud (FC) (Tornadoes or Waterspouts) .................................................................... 33 6.7 Obstructions