Using TOTS for verification at the Global Graphics desk

In the international branch of our aviation operations, forecasters issue 12 hour forecasts of jets, tropopause heights, turbulence, icing, and convection. For the summer experiment one of our desks is issuing these products, but focusing mainly on the convection forecast. As is typical for the international branch, the forecasting is a challenge but the verification is nearly impossible. With much of the global domain over ocean there are very few surface observations with which to verify the presence of convection.

For this reason we explored using the Tropical Overshooting Tops (TOTs) as a verification tool. Shown below is yesterdays global graphics convection forecast, valid 12Z this morning. Overlaid is the TOTs from 1130 - 1200 Z. Note the area near the Yucatan Peninsula that was very well forecast and also the area in the mid-Atlantic within the ITCZ that was missed.

The 20130813 12Z global graphics convection forecast valid at 12Z today (blue scalloped bubbles), overlaid with Tropical Overshooting Tops from 1130 - 1200Z. Note the TOTs within the bubbles as well as the TOTs not within the forecasted zones (particularly in the Atlantic). In this particularly case the forecasters did relatively well, missing only one significant area in the Atlantic along the ITCZ