When to fly

From ParaWiki

Ask seasoned pilots

As a beginner it's a little intimidating to find out the sweet spot between a mediocre and a dangerous day for flying. Join a social media group (there are an endless amount on WhatsApp / Facebook) and observe. Some pilots are very happy to share their flying forecasts, others less so.

For Cape Town the surrounding area, consider the Glen Country Club's paragliding WhatsApp groups by scanning the QR codes on the website with your phone: https://www.glenclub.co.za/paragliding/

Also, don't ask: "Where can we fly tomorrow?" (then you're just giving your work to other people). Rather say: "I looked at the surface winds, winds at elevation, temperature, and rain forecast, and I think that site X might work tomorrow. I'd appreciate it if you can tell me if I'm completely off the mark here or if anyone has other suggestions."

Below is how I plan for an upcoming flight, starting about three or four days before a planned flight.

Surface wind and gusts

You need to safely launch and land, so this is a good place to start.

  • I use Windy and monitor it until the moment of launching (and sometimes during my flight if my flight plan changes).
  • RASP (The South African Regional Atmospheric Soaring Prediction) shows the surface wind and often can be more accurate about incoming afternoon gusts than Windy. It's most accurate for the next day's flying (updated 6pm, SA time) and the actual day of flying.
  • There are also a good amount of "wind talkers", remote weather stations around South Africa that report actual current weather conditions.
    • iWeathar (a list of stations, but also a free app for iOS and Android - highly recommended to check wind changes before and during your flight)
    • Cape Kiting - the Glen (a new weather station at the Glen Country Club for Lion's Head landings)
    • Kommetjie Weather Conditions (not very mobile friendly, but very useful for flying Cape Town's "Deep South")

The wind shouldn't be too light (especially for a ridge soaring site), but neither should it be too strong for you to safely launch or land.

Always write down the predicted (and/or actual) wind speed and other weather conditions after flying a site to find your personal sweet spot.

Wind and gusts at elevation

Wind speed, gusts, and direction can be significantly different at different altitudes. Both Windy and RASP (and other sounding forecasts) allow you to see predicted wind at elevation.

Wind at altutide with Windy

On Windy, select the date and time of your planned flight. Move to the area and select (right click on web, tap and hold on the mobile app) "Show weather picker" (this will show the wind speed, for the Basic forecast as below; wind lines and speed will show on that point if you select Wind forecast). Then use the slider to see what the wind is going to do at higher elevation:

1. Select the weather picker
2. Select the right date, time and that it shows surface winds
3. Change the elevation (note the significant increase in wind speed)
Wind at altutide with sounding / Skew-T / RASP

(More on sounding charts further down)

The wind barbs on the right-hand side of sounding graphs have all the information you need. The long line ("flagpole" or "vector") shows you the wind direction, other lines show the wind speed: short lines mean 5 knots (9.3 km/h), longer ones 10 knots (18.5 km/h), triangular ones 50 knots (93 km/h), or a combination thereof.

Note that some sounding charts will indicate altitude in pressure -- hPa (hecto Pascal) or millibars-- others in feet, others in metres, etc. Just convert these as needed.

Windy.com sounding chart
RASP sounding chart

Precipitation

Paragliders sink, spin, and stall very easily when wet, so rain means no flying.

Some clouds are great for flying, others are very bad, others are neither good or bad. Learn to identify them.

I use a combination of Windy (the Basic forecast and Airgram views), RASP, and yr.no to predict cloud cover and probability of rain.

Sounding / Skew-T

Learn to interpret these diagrams, it's probably the most important out of the lot. They show you a multitude of information about the sky above you in one image, including:

  • temperature and dew point
  • wind speed and direction
  • instability (good) and inversions (bad)
  • cloud base and more

It will help you immensely in understanding what may make a good or a bad flying day.

Some videos:

Wind speed and direction in the Western Cape

Below are rough guidelines on surface wind speed for some Western Cape sites for licensed pilots. If you're a student, ask your instructor.

  • Hermanus: Up to 18-20km/h (and even 22-24km/h, but you'll have to have good ground handling and wing killing skills)
  • Porterville (Dasklip, Pampoenfontein, Kardoesie): Up to 18km/h
  • Piketberg. Max 12km/h.
  • Sir Lowry's Pass: Max 12km/h (but for beginners around 8km/h and below, since the wind creates a strong venturri at takeoff).
  • Franschhoek. Ideally 6-10km/h. Anything forecast in the double-digits means it will probably be PUMPING at launch (and makes bottom-landing a safer alternative), since the whole Franschhoek valley constricts at that point.
  • Langebaan. Max 24km/h (launch lower down the slope; one can fly and land in slightly stronger wind, depending on skill)

Here is a helpful wind rose for the Western Cape:

South-africa-windrose.jpg

More useful info

  1. A good day to fly? Go fly!
  2. A little strong? Find a place to practice ground handling (an hour on the ground = ten in the sky)
  3. Raining or too strong to ground handle? Watch videos, read books/articles, listen to podcasts, study meterology.