Buoyancy/Shear Ratio

[Soartech]

What do you think about the BLIPMAP Buoyancy/Shear Ratio parameter?
Is it accurate that less than 7 makes the day difficult to work?
I have found lately that this seems to be true but my sample size
is small. I am in the northeast US. Location is probably a factor.

[Steve Leonard]

I had heard 5 was where it started to get tough. I have gone cross country on days with the forecast of 2. Not easy, but if cross country was easy, any monkey could do it! I would not pass on a day just because the forecast B/S ratio is low. I have had fairly smooth thermal climbs with winds of 35 to 40 MPH here in the midwest. I have also had very rough and broken climbs with winds less than 10 MPH.

Steve Leonard
Wichita, KS

[Tony]

Usually accurate but like Steve I've had good thermals on days with very low B/S, like when I flew 525 miles in a 30-40mph tailwind

[Tango Eight]

The best thermals on any given day have better buoyancy, so better B/S ratio.

Days with a lot of shear put an absolute premium on thermal selection. I'd put the number where things start getting choppy at around 5.

-Evan Ludeman / T8

[Papa3]

Agree with Evan and Steve above. A lot depends on your course selection as well. Crosswind legs on low B/S ratio day can be brutal. Upwind/downwind usually better. Also depends a lot on pilot thermaling ability. Low B/S days typically require "dynamic" thermalling (push/pull/stomp - whatever it takes to go up).

P3

[Ramy]

Agree with all the comments above. In general windy blue days are more difficult. I normally don't check the B/S ratio as the BLtop, wind, cu potential and cu base (as well as convergence and total cloud cover) provide sufficient information.

Ramy