Polar Jet Stream
Once you load the
bundle, go to the Side Legend in the Display Window. Then move ahead to 6z (1 AM EST)
on January 30th by hitting the next image button of the toolbar (next to the play
button in the top right corner of the display window). Uncheck the box next to the 55 m/s wind speed and the 45 m/s wind speed. This should give you an
image similar to Figure 3. Looking at the 300 mb pressure and surface temperature,
notice the upper-level ridge in the western part of the country and the trough
in the eastern part of the country. Note that the western states are experiencing
warmer temperatures than the eastern states. Also, note that the polar jet
stream appears to be in the area of the largest surface temperature gradients
and where the 300 mb geopotential height contours are tightest, making
it more important to forecasters than the sub-tropical jet stream. During
the winter months, the surface temperature gradients are strongest and farthest
south, causing the polar jet stream to be stronger in the winter than the summer.
