Comparing wind speed with geopotential height and temperature, migration of the subtropical and polar jet streams may be inferred. During winter months, geopotential height values and the stratosphere lower, while upper-level westerly winds increase considerably. The opposite is true during the summer months of July and August when the polar jet stream is over northern latitudes and the subtropical ridge extends across Florida. This leads to a pronounced decrease in upper level winds and more directional variability. Wind speeds increase with height up to 200 mb then decrease at 150 and 100 mb.
All levels have winter maxima and summer minima.
In the lowest levels, wind direction is much more variable during winter, but in middle levels wind direction is more variable during summer. At 200 mb, winter wind directions show a consistent westerly flow associated with the subtropical jet stream. During spring and fall, winds aloft become more variable in direction, while lower level winds are primarily from the northeast and southeast quadrants. Winds are evenly distributed at 500 mb, and the mean subtropical ridge position produces northeast to east winds above 500 mb during summer. Average 1200 UTC mandatory level temperature, wind, and dewpoint data were plotted from 1000 mb to 100 mb.