As Tinstaafl said, on sig Wx charts and the like there is usually a 'geostrophic wind scale' for equating the isobar spacing and latitude with the windspeed. Doesn't account for Jets though, but they should be on the chart anyway.
If yoyu've got access to Met charts anyway, it's far easier just to get the upper wind charts as well as a synopsis!
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...proceeding below Decision Height with CAUTION...