2009 Audi Hamilton Island Race Week Day 3 Weather

Just after Sunrise Day 3 - 2009 Audi Hamilton Island Race Week Day 3 Sail-World.com /AUS http://www.sail-world.com

Day 3 4am - 2009 Audi Hamilton Island Race Week © Bureau of Meteorology http://www.bom.gov.au

Synoptic Discussion:

The aerodrome forecast or TAF for Hamilton Island sums up today very nicely – variable in direction averaging 7knots ! Just like yesterday you say!


A ridge of high pressure still lies over the race area.

Observations:

At 0600hr the surface wind at Hamilton Island was calm, (temp 20C, pressure 1016hPa) indicative of the very weak gradient. At Hardy Reef (further offshore at 19.7S 149.2E) the wind was NE at 7kn.

Forecast Winds for open water 4nm East of Surprise Rock (i.e. east of Hamilton Island) (Read Discussion below)

1000:MD100 DR(040-150) MS05 SR00-09kn chance glass-out?
1200:MD090 DR(040-130) MS05 SR00-10kn chance glass-out?
1400:MD080 DR(040-120) MS06 SR02-11kn
1600:MD070 DR(040-120) MS05 SR02-10kn
1800:MD070 DR(030-110) MS05 SR02-10kn

Note 1: First column is mean wind direction in deg Magnetic (MD). It is the
10min average (mean) value at a height of 10m above the water leading up to the hour quoted. The second column is the directional range (DR) of the wind direction in deg Mag. This takes into account the natural oscillation of the wind and is a function of the atmospheric stability, etc. The third column is the mean speed (MS) in knots (kn) and is the average 10min value leading up to the hour quoted at a height of 10m above the water. The last column is the wind speed range (SR) in knots and is the lowest wind speed to highest wind speed in the 10min leading up to forecast hour.

Day 3 prognosis copy - 2009 Audi Hamilton Island Race Week © Bureau of Meteorology http://www.bom.gov.au

Discussion

This forecast has again been extremely difficult to construct with model guidance everywhere due to the light nature of the synoptic situation.

Again like yesterday, it won’t be a good day from a wind vs tide perspective.

With the very loose ridge axis still over the area, the winds will be light and flicky again today. There will be an overall tendency for the wind direction to draw onshore due to the sea breeze component. Like yesterday there is the potential for pockets of stronger wind to occur so be prepared for another Great Race Course Relocation Armada.

The sea breeze potential is expected to be greatest within 0.5 to 1nm of the eastern side of Whitsunday Island and within a 1nm or so of the mainland due to greater land/sea temperature difference.

Wind will be lighter and very flicky close in the lee of any landmass e.g. Whitsunday Island, etc.

Be extra, extra careful again today with the light wind coupled with strong ebb and flood tides.

Natural oscillations today around 50 to 180 deg!

Weather

Some early low cloud then dry and partly cloudy. Take plenty of sunscreen and warm clothes in case?
Maximum land temperature at Hamilton Island: 25-26 degrees. Sea Temperature: about 23-24 degrees.

Wind Waves:
0.0 to 0.2metres, less in lee of land, more when wind wave opposes tidal current.(Wave heights quoted are Significant wave heights).

Current: A strong flood this morning followed by a moderate ebb later this afternoon. Be extremely careful in channels, etc.
Remember: Tide floods to the south and ebbs to the north in the Whitsundays.

Tide at Shute Harbour: Low of 0.53m at 0709hr and High of 2.97 at 1333hr and Low 1.00m at 1932hr.

Outlook

Tuesday: Lay Day – have a break you deserve it.

Thursday to Saturday are still shaping as fresher Trade Wind days. Bring it on you say?