AVIATION WEATHER OBSERVATIONS for …

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

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 Effective

No.

Date

Initials

Date Entered

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.

ii

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

iii

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.................................................................................................................................... 4-1 4.2.1 Prevailing Visibility ............................................................................................................ 4-1 4.2.2 Sector Visibility .................................................................................................................. 4-1 4.2.3 Surface Visibility ................................................................................................................ 4-1 4.2.4 Variable Prevailing Visibility ............................................................................................. 4-1 4.2.5 Visibility ............................................................................................................................. 4-1 4.2.6 Visibility Markers ............................................................................................................... 4-1

4.3 Observing, Determining, and Reporting Procedures ................................................................... 4-1 4.3.1 Unit of Measure .................................................................................................................. 4-1 4.3.2 Observing Aids for Visibility.............................................................................................. 4-2 4.3.3 Observation Sites ................................................................................................................ 4-2

iv

4.3.4 Selection of Visibility Markers........................................................................................... 4-2

4.3.5 Dark Adaptation.................................................................................................................. 4-2

4.3.6 Determining Visibility ........................................................................................................ 4-2

4.3.7 Determining Prevailing Visibility....................................................................................... 4-2

4.3.8 Variable Prevailing Visibility ............................................................................................. 4-3

4.3.9 Sector Visibility .................................................................................................................. 4-3

4.3.10

Reportable Visibility Values................................................................................... 4-3

CHAPTER 5 - PRESENT WEATHER ......................................................................................... 5-1

5.1 Introduction.................................................................................................................................. 5-1

5.2 Definitions.................................................................................................................................... 5-1 5.2.1 Precipitation ........................................................................................................................ 5-1 5.2.2 Obscurations ....................................................................................................................... 5-2 5.2.3 Other Weather Phenomena ................................................................................................. 5-2

5.3 Weather Observing Standards...................................................................................................... 5-3

5.4 Present Weather Reporting Procedures ....................................................................................... 5-5 5.4.1 Precipitation ........................................................................................................................ 5-6 5.4.1.1 Determining and Reporting Precipitation ............................................................... 5-6 5.4.1.2 Determining the Character of Precipitation ............................................................ 5-6 5.4.1.3 Determining and Reporting the Intensity of Precipitation...................................... 5-7 5.4.2 Obscurations ....................................................................................................................... 5-7 5.4.3 Other Weather Phenomena ................................................................................................. 5-7 5.4.4 Thunderstorm...................................................................................................................... 5-7 5.4.5 Tornadic Activity ................................................................................................................ 5-8

5.5 Other Significant Weather Phenomena........................................................................................ 5-8

CHAPTER 6 - SKY CONDITION................................................................................................. 6-1

6.1 Introduction.................................................................................................................................. 6-1

6.2 Definitions.................................................................................................................................... 6-1 6.2.1 Sky Cover............................................................................................................................ 6-1 6.2.2 Summation Layer Amount.................................................................................................. 6-1 6.2.3 Layer Height ....................................................................................................................... 6-1 6.2.4 Ceiling................................................................................................................................. 6-1 6.2.5 Type of Clouds.................................................................................................................... 6-1

6.3 Observing Standards .................................................................................................................... 6-1 6.3.1 Layer Opacity...................................................................................................................... 6-1 6.3.2 Surface ................................................................................................................................ 6-1 6.3.3 Sky Cover............................................................................................................................ 6-2 6.3.3.1 Clear Skies .............................................................................................................. 6-2 6.3.3.2 Layer Amounts........................................................................................................ 6-2 6.3.3.3 Summation Layer Amount...................................................................................... 6-2 6.3.3.4 Variable Amounts of Sky Cover............................................................................. 6-2 6.3.4 Stratification of Sky Cover ................................................................................................. 6-2 6.3.5 Evaluation of Multiple Layers ............................................................................................ 6-2

v

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download