Wind in general, and jet streams in particular, are ultimately driven by temperature contrast [and of course modified by earth rotation].
I have no idea if jet streams are becoming faster: the period of accurate measurement is too brief to be very informative [only Aireps or whatever, many and often, give enough data, and then only on busy routes].
If they are becoming faster, surely the circulations outside the cores will also be faster, as part of the global mechanism for distributing the unequal heating of the planet polewards.
This being so, I cannot see why sheers [contrasts] of wind vector might be increasing.
And I still don't know what these "intersections" are.