Dynamics of Tornadic Thunderstorms

A time-split nonhydrostatic atmospheric model for weather research and forecasting applications

“…The perturbation variables, along with (18), are substituted into the prognostic equations and lead to the acoustic time-step equations: d s U 00 þ P x ðp 00 ; a 00 ; / 00 ; l 00 Þ s ¼ Àr Á ðVuÞ…”

“…Most obvious is that the simulated reflectivity for the 4 km simulation depicts cells that are significantly larger and stronger than was observed. The 4 km grid also does not allow resolution of some of the defining characteristics of supercell storms, in particular the low-level mesoscyclone (storm-scale cyclonic circulation in the storm, see [18,21]) and propagation to the right of the low-level windshear vector (see [18]). Higher resolution does alleviate some of these problems.…”

How does mid-tropospheric dry air affect the evolution of supercellular convection?

“…3a-d); which was the result of the storm splitting (not shown). Subsequently, the right-moving (southeast) cell dominated over the left-moving (northwest) cell because the base state had a veering shear (e.g., Klemp, 1987). In DRY40 and DRY10, low-θ e air (θ e b 330 K), in which the anomaly of water vapor mixing ratios (q v ′) was less than −6 g kg −1 , was found in the forward-flank region of the rightmoving cell (Fig.…”

“…This sounding has large CAPE and strong veering shear, which promotes the development of deep, right-moving supercellular convection rather than left-moving convection (e.g., Klemp and Wilhelmson, 1978;Klemp, 1987). The storm relative environmental helicity was 101 m 2 s −2 .…”

Sensitivity of tropical cyclone intensification to inner-core structure

“…This indicates that there is vertical shear of the primary circulation and thus horizontal vorticity. Once the deep convection is triggered, each updraft will induce vorticity dipoles with negative and positive sign on either flank of the updraft, which is due to the tilting term in the vorticity tendency equation (Klemp, 1987). These vorticity dipoles will be split due to the vorticity segregation process (Schecter and Dubin, 1999;Van Sang et al, 2008).…”