Its that time of year, when attention is frequently turned to the erratic behavior of dynamic transient airstreams of circulating moist warm air in the South China: Yes Sea. Yes its Typhoon Time.
And with Typhoon Time the thoughts of Dive Marshalls (DM) and the Diving Officer (DO) turn to the likely impact on upcoming dives and sort through the mass of sometimes conflicting data. Then to suck a deep breath and say, yea or nea to the dive going ahead. Frequently the issue is clear cut, particularly when a T3 is up, but sometime errors can be made and this article is principally being written as a "mea culpa" on a Saturday in early July, when I should be sploshing around in the waters of Sai Kung instead of studying my belly button.
On Thursday preceding the dive the T1 was hoisted, and your DO and DM for the day (originally Ron, but then it was considered it would be difficult for him to marshall from Italy, so Jason stepped in), started paying close attention to forecasts and other information regarding "Kai Tak" – was it coming home?
For a Saturday or Sunday dive the "go/don’t go" decision must be made by Friday lunchtime in order to contact everybody (particularly those whose main contact is by work email) and ensure Mr Yip does not bring the Junk from Sai Kung unnecessarily. In order to form a view there are some good sources available, principally Weather Underground http://www.underground.org.hk/, and the
HK Observatory.
Close attention had been paid to the track of the typhoon in the last couple of days and it appeared that the
US Joint Typhoon Centre which can be accessed through Weather Underground had been most accurate in the predictions with Kai Tak plotting a NW course which would result in a close hit on HK and definitely rule out diving (see 2:00pm prediction, right). The Observatory (HKO) over the initial passage of the typhoon had been consistently suggesting a more northward track.
Having cancelled a dive earlier on in the year on the advice of HKO due to a black thunderstorm warning that actually brought a day of beautiful sunshine I was less than mindful of their advice. So armed with the prediction at 2:00pm a series of call were made and the dive cancelled. Unfortunately new projections of data available at 6:00pm (see left) suggested that the storm was slowing and would track northwards. This suggested that the HKO had in fact been more accurate this time, but by then it was too late to rebook kit & boat, and heavy squalls and rain were still forecast.
As I write this we have had, apart from a torrential 1 hour squall a beautiful day and the latest report downloaded shows that Kai Tak spent most of Friday evening stationary and dawdling in circles NW of the Philippines before heading in a NE direction, an option that had been ruled out by all the experts on Friday itself.
So short of enrolling all DO’s and DM’s on an advanced meteorology course to assist in the analysis of data and projections I regret that errors will happen, for which I apologize in advance. But at least have some comfort that I am not alone, and the fickle nature of typhoons defeats the best cranial and numerical efforts of forecasters throughout the region.
Of course I should have heeded Mr Yip’s advice who said let’s move the boat to Sai Kung and wait and see. Unfortunately the logistics of equipment, and people do not permit this, and anyway, what does Mr Yip know, except for 50 years experience on boats!.
So please in the upcoming months if you are diving keep an eye on your emails on Friday afternoon/evening where the DO will hopefully get it right next time.