Upper-Level – Wind

On upper-level maps at 250mb, upper-air observations of winds, temperatures, and dew point temperatures are plotted. The most important feature on upper-level maps are the wind speeds and directions showing where the jet stream and jet streaks are located. Jets of stronger wind speeds are indicated by the blue shading where weather balloons recorded stronger wind speeds at the 250mb level. In addition, the SPC 250mb maps show solid gray lines representing streamlines. These streamlines simply represent the direction of the flow of upper-level winds.

In the above 250mb analysis, there is a jet of strong upper-level winds extending from the Pacific Northwest down into the Gulf of Mexico. This jet rounds an upper-level trough and extends northward into the Carolinas along the East Coast of the United States. This upper-level trough lines up with the mid-level trough seen on the 500mb analysis seen in previous lessons. A jet streak of strong upper-level winds is present along the coast of Georgia and South Carolina. This jet streak may provide some increased support for rising air leading to precipitation and thunderstorms. As discussed in previous courses, the most favorable regions of the jet streak for rising motion are in the right entrance region and left exit region. Analyzing 250mb maps to find these jet streaks is often important to understanding where severe weather is likely given other supportive factors are present, such as moisture, instability, and lifting mechanisms.