seeing turb?

[Canadian eh]

question for any pilot out there. a pilot today requested to dev. 5-8 miles north of course for turb. the controller working him at the time said "confim you want dev. north of course?" and he came back and said "no i want to dev. 5-8 miles north of course for turb, i can see it's a smooth ride there" it wasn't a conflict with other traffic so he gave it to him. how can he see turb? we got thinking about it and the only thing we could come up with was maybe he had another aircraft on his tcas and was in his wake. that being said he was at fl250 and we display all targets up to fl302, the only wake he could have been in would have been a guy at fl310 or higher, 6000' should be enough to kill a wake.  another controler when told about this later thought maybe he was or the great lakes and that would take him beyond the shore but that wasn't the case cause he was still a good 25 miles from shore after dev. any ideas how he could "see" the turb

[KSYR-pjr]

any ideas how he could "see" the turb

Two ideas come to mind:

1)  There was a towering cumulus cloud directly in his path and deviating 5 miles north would take him around it.  All pilots know that flying into a cumulus cloud will result in teeth chattering turbulence.

2)  (just a SWAG based on some aviation mag reading)  The aircraft is equipped with a type of radar that does detect turbulence. 

[KSYR-pjr]

Oh, forgot to mention previously - one other type of cloud is also indicative of turbulence.  It is called a standing lenticular cloud and it typically forms above very strong turbulence near or downwind of mountains. 

Here is a link to a dramatic picture of a lenticular cloud and a brief explanation of how they form.  Note that these clouds can form way above mountains, not just at the peak as shown in this picture.

http://www.crystalinks.com/lenticular.html

[rpd]

I would say he could see clear sky to deviate into.  It seems lately that even airline pilots don't want to fly through any clouds, regardless of type cloud.  They are always asking for deviations, or you can see small course changes on radar.

[Unbeliever]

It probably was a cloud avoidance divert, but there's a trick for those with strikefinders. You can 'see' clear-air-turbulence coming. 

The triboelectric buildup and discharge around the CAT layers will set off a lightning strikefinder. If you're in the right mode, and there's not a cloud ahead of you, and your strikefinder is tagging multiple strikes where there are no clouds, there's a good chance of CAT.

--Carlos V.