Hamilton Island Weather Day 3

by Kenn Batt, sponsored by North Sails on 23 Aug 2005 Weather Forecast for 2005 Hahn Premium Race Week brought to you by North Sails

“North Sails proudly assisting the Premium Tropical Regatta”

For Tuesday 23rd August 2005 Issued at 0600hr

Synoptic Discussion:

A ridge of high pressure is expected to build over the region today and persist for at least the rest of the race series.

Observations at 0600hr:

There were nil precipitation echoes on the radar.
Surface wind at Hamilton Island was 170deg Magnetic at 6kt. At Hardy Reef (19:44.04S/149:10.85E)it was 110deg mag at 6kt.

Forecast Winds for Open Sea Area East of Hamilton Island

1000:150/10 gust 14kt
1200:140/13 gust 17kt
1400: 130/15 gust 20kt
1600: 120/16 gust 21kt maybe as far left as 110 degrees?
1800: 140/16 gust 20kt

Wind direction possibly 5 degrees more veered (right) over southern race area and 3-5 knots lighter closer to land.

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. Alternate bands of maximum and minimum wind speed, some 5-10 mins apart, normally characterize trade wind flow.

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: 70%, based on state of art forecast models and grey matter.
Other Possibilities
40% chance that wind speed will be 2-3 knots stronger than forecast above particularly later this afternoon.
40% chance that direction makes it as far left as 110 degrees during the afternoon and goes left faster than forecast above.
20% chance that wind direction could veer (go right) 10-15 degrees after about 3pm.

Weather

Dry and partly cloudy. Take plenty of sunscreen, warm clothes and wet weather gear.
Maximum land temperature at Hamilton Is: 24 degrees Sea Temp: 20 degrees

Wind Waves: 0.4 to 1.2 metre. Less near land. Note that wind opposing tide can create higher than forecast wave heights Swell: ESE around 0.5m. (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 generally, marked localised variations occur. Consult chart and 100 Magic Miles for further information.

Outlook

Wednesday: Chance shower. SE winds 20/25 knots.

Thursday: Showers. SE winds 20/25 knots.

Friday: Showers. SE winds 20/25 knots.

Saturday: Showers. SE winds 20/25 knots

Tides for Shute Harbour


Tue 23 Wed 24 Thu 25 Fri 26 Sat 27 Sun 28 Mon 29

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

0049 3.49 0131 3.07 0221 2.63 0340 2.27 0528 2.12 0115 1.05 0209 0.83

0713 0.46 0759 0.60 0854 0.76 1006 0.88 1124 0.90 0655 2.20 0754 2.35

1326 2.92 1424 2.85 1538 2.82 1703 2.88 1824 3.06 1237 0.83 1334 0.72

1914 0.79 2020 1.13 2159 1.34 2350 1.29 1926 3.26 2013 3.40