Buoyancy/Shear Ratio

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.

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

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

On Saturday, August 1, 2015 at 10:55:32 AM UTC-4, Soartech wrote:
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.

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

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

On Saturday, August 1, 2015 at 11:50:46 AM UTC-4, Tango Eight wrote:
On Saturday, August 1, 2015 at 10:55:32 AM UTC-4, Soartech wrote:
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.

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

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