UPPER LEVEL DIVERGENCE

As we’ve discussed before on the 4029 weather blog, there are two “sweet spots” associated with a jetsteak; the right entrance region and the left exit region. Both regions develop broad scale convergence and rising motion at the surface due to divergence aloft. They are favorable spots to keep an eye on for thunderstorm development. Sometimes these regions can become overlapped when two jetstreaks are near each other, causing super-enhanced rising motion over an area. Many record breaking snowstorms are a product of such an overlaying of these “sweet spots”.

Take note of the correlation between where the moderate risk is on the map from the SPC and how well it correlates with the positioning of the jetstreak. This is not an accident. In particular, note how the area is more or less superimposed over the right entrance region. Aloft, winds diverge or spread out and at the surface they come together or converge. This region of enhanced lift, coupled with strong wind shear, ample moisture, and a cold front will likely be where most the action is tomorrow.

We may still pop some storms with the heat of the day, though the high test stuff will remain out to our west.

Posted by Ted Zarras at 3:57 PM