Conceptual Model of a TUTT Low
Upper-level cyclones normally have convergence into their centers producing downward motion and clear skies. Divergence normally occurs along the periphery of the cyclone with rising motions causing cloudy skies and precipitation, as shown in Figure 2-41. Over land, however, convective activity is often present near the centers in the afternoon when enough instability is produced by a combination of daytime surface heating and the upper-level low's cold core. The strongest convection normally occurs along the western periphery ahead of westward-moving cyclones.