Watch out for winter weather!
Yesterday's training session at Maioro seemed like the first experience of 2022 'winter weather': Colder air, the sun still feels quite warm but as soon as disappears behind a cloud, it feels cold. Squalls, rain, changes of wind direction and speed. From our arrival at Kario car park at 11.30 to early afternoon, the wind went from light NW to nothing during a rain shower, to SE after the rain to light WSW too light to soar, to SW at the top limit of the the range we can fly in before it dropped to easy soaring again. The changes were significant and quite sudden.
This isn't unusual on days like yesterday. While the forecasts showed mainly relatively steady SW wind forecasted all day, the local wind was hugely affected by the squalls / rain clouds. Showers were forecasted, which is your big warning sign. The other is the dropped temperatures which make for denser air.
Typically, changes in wind around the squalls go as follows: When a squall approaches, the wind in front of it often increases in strength pushing ahead and in the direction of the squall travelling towards you. In case of bigger thunderstorm clouds, this is called a gust front. Such is caused in part by the rain falling down and pushing air along. So whether you are in front of or on the side of such cloud and shower, makes a huge difference in the wind you experience. That was clear by the fact that Reuben, who was at the Kario high side a few kilometres North, experienced noticeably different direction and strength of wind, especially when some showers went in between the Maioro training site where most of us were and his position.
Once it starts raining, you typically feel less wind and it can be any direction, but typically light from the general direction on the day. Once you reappear from your shelter right after the rain has passed, the wind again can be any direction and often very light. In our case yesterday, it was a light SE. It then takes a little while, perhaps 15 mins for the wind to go back to it's 'real' direction of the day, in our case SW. It was nice and light, great for launch and landing practice and too light to soar for an hour or so, before it quite suddenly picked up and went to the top range of flyable conditions. There was a warning to be seen in a change of colour and texture on the water, rather distance white caps which weren't that easy to see with the dramatic low light and the general patchy sunny and shady water surface. Later in the day, it dropped back to a lighter, more southerly wind.
The trick was to feel warned simply by the fact of the generally shower forecast and obvious showers around, the winter conditions, the knowledge that such conditions make for very changeable air, and then to observe very carefully during they day. The change on the water was visible, as that came closer, we could see some small low cumulus racing towards us.
Flying on the coast has the most definite advantage that you can see changes in conditions many kilometres ahead (that's miles for those hanging onto the comfort of imperial). It takes practice to read it well, so if in doubt what a colour or texture change means, make sure to be on the ground during the change, land if you have to, don't launch, even if you are all set to go. Then reassess once you are sure you are experiencing the change where you are and make a new decision carefully. If in doubt, as always, don't fly! In the same conditions as yesterday, I would not fly in the mountains, as the changes are harder to see coming with mountains obstructing your view ahead of what is approaching. In addition, you are likely to be higher off the ground when you recognise any change which means it takes you a lot longer to get down. At the Maioro site, you can be on the ground within a minute, it is easy to get out of the lift band, there is ample 30km to land safely in windy conditions, a luxury you seldomly have around inland sites. Valleys can accelerate the wind, strong wind can cause lift and turbulence in all sorts of places which make it hard to get down and into safety.
In winter, we get such conditions more regularly. To make it worth, the air is colder and denser which exaggerates the effect on the glider and pilot. It often results in less lift on the ridge but more compression and resulting horizontal speed with a similar forecast.
In Auckland, we typically have a few incidents every winter due to the change in conditions from summer. This is compounded by the fact that us pilots can be that little bit less current and hence that bit keener or even more desperate for a flight which diminishes our decision making ability. More often than not, the odd pilot feels ambushed by increasing wind or increased compression over the hill or Venturi effect through a gap or gully and ends up going backwards and behind the hill. Of course, in most instances we get away with a scare but there is certainly potential for damage.
So, please watch out, be aware of the conditions and the challenges, practice your observation skills, make good and safe decisions!
With careful timing, everybody had amazing flights in gorgeous winter conditions! Well done everyone!