Normally jet streams depicted on the high-level SWC are marked with the wind speed symbols (50, 10, 5 knot symbols) and the pressure altitude of the core. However, some have an additional piece of information that I do not know its meaning. Below the FL410 of the core for example, there would be for example 260/550. What do they stand for?
Take a look here for example: (Jet streams over Libya, Atlantic ocean and Caribbean and some others have this extra "thing" while others do not)
