Hamilton Island Weather Day One

by Kenn Batt, sponsored by North Sails on 20 Aug 2005 Weather Forecast for Day One 2005 Hahn Premium

'North Sails proudly assisting the Premium Tropical Regatta'

For Saturday 20th August 2005 Issued at 0530hr

Synoptic Discussion:

A weakening ridge of high pressure is currently situated over race area. A cold front is moving through southern parts.

Observations at 0530hr:

There were nil precipitation echoes near the Islands.
Surface wind at Hamilton Island was 153deg Magnetic at 11kt, gusting 13kt. At Hardy Reef (19:44.04S/149:10.85E)it was 160deg mag at 14kt, both observations indicative of the general synoptic flow.

Forecast Winds for Hamilton/Lindeman Island Area in Open Water

0900:140/10 gust 14kt

1100:130/12 gust 15kt

1300:120/12 gust 16kt

1500: 110/13 gust 17kt could see 090-070 deg?

1700: 130/10 gust 14kt

Natural oscillations today around 10 to 15 deg away from effects of topography, tending around 20 to 60 deg closer to the effects of any land mass. Wind speed can be stronger due to effects of channeling between islands, etc and lighter in lee of headlands, etc.

NOTE 1: Wind directions MAGNETIC, first speed is 10 min average and last speed is
maximum one minute gust during the 10min period leading up to the forecast hour. All at a height of 10m.

NOTE 2: The trend in both wind direction and speed is the most important aspect of any marine forecast. Forecast values will differ from observed values from time to time for a number of reasons including yacht’s position within race area, compass calibration, instrument calibration, land mass in the flow, etc


Forecast confidence level: 85%, based on state of art forecast models and grey matter.
Other Possibilities

40% chance that wind speed will be +/-2 knots than forecast above.

40% chance that wind direction reaches 090-070deg mag later this afternoon.

30% chance that direction goes left faster than forecast above

Weather

Cloudy with an early clearing shower or two. Take plenty of sunscreen, warm clothes and wet weather gear.

Maximum land temperature at Hamilton Is: 24 degrees Sea Temp: 20 degrees

Wind Waves: 0.5 to 1.2 metre. Less near land. Note that wind opposing tide can create higher than forecast wave heights Swell: E around 1.5m. (Wave heights quoted are Significant wave heights). Current: A very strong tidal influence. Tide floods to the south and ebbs to the north in the Whitsundays. Marked localised variations are possible.

Outlook

Sunday: Dry. Wind: SW 5/8kt at first, tending SE/NE 8/14 kt.

Monday: Dry. Wind: S/SE winds 8/14 kt.

Tuesday: Chance of shower. Wind: S/SE winds increasing to 18/20 kt during afternoon.


Tides for Shute Harbour

Sat 20 Sun 21 Mon 22 Tue 23 Wed 24 Thu 25 Fri 26

Time Ht Time Ht Time Ht Time Ht Time Ht Time Ht Time Ht

0507 0.32 0548 0.31 0007 3.83 0049 3.49 0131 3.07 0221 2.63 0340 2.27

1100 2.92 1147 2.97 0630 0.36 0713 0.46 0759 0.60 0854 0.76 1006 0.88

1645 0.02 1732 0.18 1235 2.97 1326 2.92 1424 2.85 1538 2.82 1703 2.88

2325 4.06 1821 0.45 1914 0.79 2020 1.13 2159 1.34 2350 1.29