BRN Shear ?

[Jon Miller]

I see that the SPC Mesoanalysis page has BRN shear as one of the analyzed parameters. Their description says that it relates to supercell developement - was wondering if it can be an indicator for tornadogenises or is it of less importance and not directly related ? Thanks.

Jon Miller
KT8NDO

 

[Michael P. Morris]

The BRN Shear is the denominator in the formula for the Bulk Richardson Number, a ratio of instability (measured in CAPE) to deep layer shear (6km wind - sfc wind)^2. It's not really an indicator of imminent tornadogenesis, but more a parameter indicating where the most shear is present, much like helicity or the 0-6 km shear vector. I am not sure how it is used operationally, however.