Preliminary Report on
Meteorological Aspects
of the 1998 Sydney to
HobartYacht Race

February 1999

CONTENTS

				Page
PREFACE				i

EXECUTIVE SUMMARY				iii

1.	INTRODUCTION			1

1.1.	Background			1
1.2.	Purpose and Scope of this Report			1
1.3.	Units of Measurement, Terminology and Definitions			3

2.	THE METEOROLOGICAL SITUATION 23 to 29 DECEMBER 1998			5
2.1.	Detailed Evolution of the Surface Synoptic Pattern			5
	2.1.1.	The Surface Synoptic Pattern Leading up to the Race		5
	2.1.2.	The Surface Synoptic Pattern at the Start of the Race		5
	2.1.3.	Major Developments in the Surface Synoptic Pattern on 26/27 December		11
	2.1.4.	The Surface Synoptic Pattern on 27 December		11
	2.1.5.	Summary of Surface Synoptic Pattern Developments		14
2.2.	Satellite Pictures			14
	2.2.1.	Features on Satellite Pictures prior to the Race		14
	2.2.2.	Satellite Pictures on 26 and 27 December		14
	2.2.3.	Satellite Pictures as Surface Winds Peaked and Abated		17
2.3.	General Weather Conditions			17
2.4.	Surface Wind Field			17
	2.4.1.	The Most Dependable Wind Observations		18
	2.4.2.	Surface Wind Behaviour Derived from Post Analysis		18
	2.4.3.	Notable Wind Reports on 27 December		18
	2.4.4.	The Likely Highest Mean Winds		20
2.5.	Sea and Swell Conditions			20
	2.5.1.	Swell, Sea and Current Interactions		20
	2.5.2.	Sea State Reports		21
	2.5.3.	Indirect Estimates of the Sea State		21

3.	SERVICES PROVIDED BY THE BUREAU OF METEOROLOGY 15 to 29 DECEMBER 1998			24
3.1.	The Bureau’s Role in Maritime Weather			24
3.2.	Services provided to the Cruising Yacht Club of Australia			24
	3.2.1.	Meteorological Services Leading up to the Sydney to Hobart Yacht Race		25
	3.2.2.	Outlooks for the Sydney to Hobart Yacht Race		25
	3.2.3.	Pre-race Briefing for the 1998 Sydney to Hobart Yacht Race		26
	3.2.4.	Forecasts and Warnings for the 1998 Sydney to Hobart Yacht Race.		27
		3.2.4.1.	Issue of First Storm Warnings	27
	3.2.5.	Services to AMSA for Search Planning and Rescue		30

4.	ASSESSMENT OF THE PERFORMANCE OF THE FORECAST AND WARNING SERVICES			31
4.1.	Description of the Forecast and Warning Process			31
4.2.	Performance of the Numerical Weather Prediction System			33
	4.2.1.	Computer Models used by Bureau Forecasters		34
	4.2.2.	Outputs from Operational Computer Forecast Models		34
		4.2.2.1	Key Computer Model Forecasts	35
		4.2.2.2.	Additional Computer Model Forecasts	35
4.3.	Storm Warnings Issued by the Bureau			37
	4.3.1.	Contents of Storm Warnings Issued		37
	4.3.2.	Other Surveys and Post-Event Investigations		37

5.	SUMMARY			38

ATTACHMENTS

Executive Summary:
Attachment
E1	The first storm warnings issued.
E2	Definitions of meteorological terms used in this report.

Main body of Report:
Attachment
1	The first storm warning issued by the New South Wales Regional Forecasting Centre.
2	The first storm warning issued by the Victorian Regional Forecasting Centre.
3	Summary of weather forecast model output operationally available in the lead-up to the Race.

APPENDICES

Appendix
1	The formation of waves.
2	Marine Weather Services information sheet.
3	Observations from selected coastal observation sites.
4	Gale and storm warnings issued for the race area.
5	Special race outlooks and forecasts prepared and issued for the 1998 Sydney to Hobart Yacht Race.
6	List of publications provided to competitors prior to the Telstra Cup and Sydney to Hobart Yacht Races.
7	Special race briefing pack made available to competitors on the morning of 26 December 1998 at the Bureau’s weather briefing stand at the Cruising Yacht Club of Australia.
8	Search and rescue forecasts issued by the Victorian Regional Forecasting Centre and the Canberra Meteorological Office.

Preliminary Report on Meteorological Aspects of the 1998 Sydney to HobartYacht Race

February 1999

Preliminary Report on
Meteorological Aspects
of the 1998 Sydney to
HobartYacht Race