Meridien Marinas Airlie Beach Race Week Day 6 Weather

by Kenn Batt on 20 Aug 2009 Synoptic Discussion:

Weaker Trades today but it’s still paradise.

A weakening ridge of high pressure currently resides over the race area.

Observations:

At 0600hr surface winds over the Airlie Beach area were out of the SSW averaging around 5-8kn (land breeze plus synoptic wind) and the temperature was around 15 deg. At Hamilton Island the wind was SE’ly at 14kn gusting 15n, (temp 20C, pressure 1020hPa) indicative of the synoptic flow.

Forecast Winds for Middle of Pioneer Bay (Read Discussion below)

1000:MD120 DR(100-150) MS12 SR08-17kn

1200:MD110 DR(090-140) MS13 SR09-18kn

1400:MD100 DR(080-130) MS12 SR08-17kn

1600:MD100 DR(080-130) MS11 SR07-16kn

1800:MD120 DR(110-140) MS10 SR05-15kn

Note : 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.

Discussion

The BIG questions today are:

1. How far left will the wind direction go? Around 080-100deg by mid to late afternoon. Closer inshore in Pioneer Bay, the direction has a better chance of achieving this.

2. Maximum wind speed? There is a 60% chance that the speed will be about 2 knots lighter than forecast.

Remember: Wind will be lighter close in the lee of any landmass and stronger between islands (in channels due to acceleration).

Natural oscillations today around 15 to 20 deg away from effects of topography, tending around 30 to 50 deg closer to the effects of any land mass.

Weather
Fine though partly cloudy . Take plenty of sunscreen and warm clothes today.
Maximum land temperature at Airlie Beach: 25 but degrees. Sea Temperature: about 22 degrees. Cooler on the water though!

Wind Waves :
0.3 to 1.0metres, less in lee of land, more when wind wave opposes tidal current.
(Wave heights quoted are significant wave heights).

Current : A strong ebb for your racing today. Be very careful particularly in the Passage, Channel, etc.

Remember: Tide floods to the south and ebbs to the north in the Whitsundays.
Tide at Shute Harbour: High of 3.00 at 1029hr , Low of 0.03m at 1615hr