Colorado State University Tropical Weather and Climate Research
We are analyzing a WRF simulation of a Meiyu front event near Taiwan during June 2017. We objectively identify the Meiyu front through time in order to test the importance of several mechanisms in heavy rainfall production.
To be, or not to be, that is the question of tropical cyclogenesis. Only about 15-20 % of African Easterly Waves develop into tropical cyclones (TCs). A WRF ensemble was created with multiple TC simulations spanning the relevant parameter space for three variables; 1) the VWS magnitude, 2) the environmental humidity, and 3) the initial vortex intensity. Unmeasurable random perturbations result in widely diverging scenarios in TC genesis in moderately sheared and dry environments. Here we hypothesize that the combination of moderate shear and dry air makes an unstable condition for a vortex to intensify or decay, which implifies that TC genesis in such environments may be intrinsically unpredictable in deterministic sense. We are currently looking at the link between the deep convection and the realignment of mid-level and low-level vortices comparing the developing and non-developing ensemble members.