Weather Outlook for the Melbourne to Osaka race.

Robin Hewitt is keeping an eagle eye on the weather conditions for the Osaka fleet. We can all learn from his observations!

As the fleet moves into the more tropical latitudes, the atmospheric pressure differences become so small that recognizing wind features from the standard weather map becomes very difficult. The example weather map gives very little concept of winds on the Queensland coast.

31/03/2013 MSLP

Hence we can utilize the ‘Gradient Wind Analysis’ chart published by the Bureau of Meteorology. Click the maps symbol on the front page of the BOM site and select it from the products listed. It is necessary to select the chart according to UTC (Universal Co-ordinated Time). Australian Eastern Standard Time is 10 hours ahead of UTC, thus 0000 UTC is 10am AEST and another hour is required for daylight saving. Note the colour coding for areas with given wind strength.

31/3/2013 Gradient Wind analysis.

This chart is produced for a level in the atmosphere that has no friction effect at the earth surface. Thus winds will be about 20% less at yacht level and some 20% difference in direction. Interested students may care to read the explanation link at the top of the chart on the Bureau site. Note also that the South-East trade winds are currently much weaker due to a weak high of 1015mb while there is a large area with good winds (green) for the North-East trades. The notations have been inserted.-Robin Hewitt.