The jet steam maps produced by NOAA are among the ?upper air? weather
maps and are indicated by the pressure, measured in millibars (of
Typically the maps that you see on television portraying the jet
stream are at the 500 millibar level ? about 18,000?. Though might
some consider this as too low for the actual ?jet stream,? which is
considered to be at the base of the troposphere, my experience as a
pilot indicates that by that altitude the higher level air flows are
consistent in both speed and direction. (Speeds tend to be lower and
change by 90 degrees or more at lower altitudes.)
?Power from Above ? the Jet Stream,? (Carr, undated)
The charts produced for the 500mb and higher levels don?t quite look
like the neat diagrams that we see on TV weather forecasts, but give
an precise depiction of wind flows. You?ll find the 4-level summaries
on the Ohio State weather pages to be a good summary of all of the
upper air maps:
Ohio State University
?Upper Air Data?
You can also find forecasts here at the San Francisco State University
site, these done at the 300 mb level. These cover worldwide data:
?Jet Stream Analyses and Forecasts at 300 mb?
Note too, that a large number of other NOAA and even FAA reports rely
on this data. Pilots can pull winds aloft reports as part of their
DUATS briefings that provide winds at levels up to about 50,000?.
Google search strategy:
Jet stream + ?winds aloft?
?upper air? + jet stream
?jet stream? + millibars + definition
?jet stream? + forecasts