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Convective Initiation in an Idealized Cloud Model Using an Updraft Nudging Technique

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  • 1 Department of Atmospheric Sciences, University of North Dakota, Grand Forks, North Dakota
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Abstract

Previous cloud modeling studies have noted difficulty in producing strong, sustained deep convection in environments with convective inhibition and/or midlevel dryness when the thermal bubble technique is used to initiate convection. This difficulty is also demonstrated herein, using 113 supercell proximity soundings—most of which contain capping inversions and some amount of convective inhibition. Instead, by using an updraft nudging initiation technique, substantially more supercells result and for a longer period. Additionally, the number of supercell-producing cases is maximized when updraft nudging is applied for only the first 15 min of cloud time near the top of the boundary layer instead of longer/shorter periods or when nudging is applied near the surface.

Corresponding author address: Jason Naylor, NorthWest Research Associates, 3380 Mitchell Ln., Boulder, CO 80301. E-mail: jnaylor@nwra.com

Abstract

Previous cloud modeling studies have noted difficulty in producing strong, sustained deep convection in environments with convective inhibition and/or midlevel dryness when the thermal bubble technique is used to initiate convection. This difficulty is also demonstrated herein, using 113 supercell proximity soundings—most of which contain capping inversions and some amount of convective inhibition. Instead, by using an updraft nudging initiation technique, substantially more supercells result and for a longer period. Additionally, the number of supercell-producing cases is maximized when updraft nudging is applied for only the first 15 min of cloud time near the top of the boundary layer instead of longer/shorter periods or when nudging is applied near the surface.

Corresponding author address: Jason Naylor, NorthWest Research Associates, 3380 Mitchell Ln., Boulder, CO 80301. E-mail: jnaylor@nwra.com
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