Geel Kerneels, the Pax, and the Gust Front

[Bundy]

Seems you are not alone James...I hope to never experience what you went through! made me go research a little and here is some interesting stuff related to the discussion.

Gust F radar.jpg (68.31 KiB) Viewed 1163 times

Gust front radar.jpg (84.84 KiB) Viewed 1163 times

shelfcloud.jpg (27.57 KiB) Viewed 1163 times

From the radar images above (all in USA) it is clear how the gust front occurs....and just how dangerous it is. The following videos are of similar weather...James I think we are lucky to still have you around!

Check how quickly it changes…see the slow (at first) increase in wind speed….then it hits you… just as Asterix described.

http://www.youtube.com/watch?v=9Nhdjv24UPw

Perfect footage of a shelf cloud… watch for the Quantas flight that passes around in front! This thing is bad news!

http://www.youtube.com/watch?v=1499p903jWw

I must admit I’ve seen some hectic storms up on the Highveld but I have never seen cloud formations like the ones on the “prairies” in USA.

http://www.youtube.com/watch?v=RqqCESro-rc

Watch this timelapse footage of a Huge CB developing….gives you a great idea of the forces involved.

http://www.youtube.com/watch?v=36vGiE5J ... re=related

Some more timelapse stuff… flipping amazing, and beautiful…as long as you on the ground!

http://www.youtube.com/watch?v=8j2Xp2nH ... re=related

[Asterix]

Some more info:

From Wikipedia:

"A gust front is the leading edge of cool air rushing down and out from a thunderstorm. There are two main reasons why the air flows out of some thunderstoms so rapidly. The primary reason is the presence of relatively dry (low humidity) air in the lower atmosphere. This dry air causes some of the rain falling through it to evaporate, which cools the air. Since cool air sinks (just as warm air rises), this causes a down-rush of air that spreads out at the ground. The edge of this rapidly spreading cool pool of air is the gust front. The second reason is that the falling precipitation produces a drag on the air, forcing it downward. If the wind following the gust front is intense and damaging, the windstorm is known as a downburst."

GO READ THIS:

http://www.aviationweek.com/aw/generic/ ... t%20Fronts

If you look at the first pic below it shows the stages of a gustfront. Stage 1 formative, in the main picture, is basically underneath the storm - not what happened. But if you look at the thumbnails - I was probably caught in stage 3, with the storm behind me, towards my 07 o'clock. Stage 3 and 4 occurs MILES away from the actual storm itself.

This would make sense in terms of my experience, since those red arrows whirling up, caught up with me from behind, inducing the sudden increase in airspeed and vertical velocity, followed by the purple arrows as it moved pass me and made my airspeed drop like a stone, leaving me stalled. In quite a high nose-up attitude, I may ad, as I was pushing bar to bleed airspeed.. )

[Asterix]

From my link above - the following seems relevant to what I encountered:

"Old gust fronts can be found in clear air more than 20 miles away from the generating thunderstorm(s). These gust fronts can still produce a strong shear zone and cause the surface wind to change rapidly." (This is probably what happened - I was in stable air at the time, and the thunderstorm was towards Bethal, miles away)

"Turbulence Threat: Definition: Encounter with man-made or atmospheric scales of motion that cause intense, short-lived, random accelerations on the aircraft." (Thus the sudden uncontrollable increase in speed and vertical speed)

"Wind-Shear Threat:Definition: Encounter with atmospheric events that cause critical reduction in airspeed or altitude, such as to threaten the ability of an aircraft to remain airborne." (Thus the stall. Although I might have induced it whilst pushing on the bar trying to keep down airspeed)

Bottom line: Dis nie lekker nie - voel soos doodgaan! So moenie gaan vlieg as daar groot Cumulonimbus aan die bou is nie - al dink jy hulle is ver. The minute that bugger starts to collapse on itself and produces a thunderstorm, you are screwed. , even if you are miles away.

You are gonna join the , physically and spiritually.!

[Asterix]

removed. double posting