Convection Initiation Caused by Heterogeneous Low-Level Jets over the Great PlainsSource: Monthly Weather Review:;2018:;volume 146:;issue 008::page 2615DOI: 10.1175/MWR-D-18-0002.1Publisher: American Meteorological Society
Abstract: AbstractObservations from three nights of the Plains Elevated Convection at Night (PECAN) field campaign were used in conjunction with Rapid Refresh model forecasts to find the cause of north?south lines of convection, which initiated away from obvious surface boundaries. Such pristine convection initiation (CI) is relatively common during the warm season over the Great Plains of the United States. The observations and model forecasts revealed that all three nights had horizontally heterogeneous and veering-with-height low-level jets (LLJs) of nonuniform depth. The veering and heterogeneity were associated with convergence at the top-eastern edge of the LLJ, where moisture advection was also occurring. As time progressed, this upper region became saturated and, due to its placement above the capping inversion, formed moist absolutely unstable layers, from which the convergence helped initiate elevated convection. The structure of the LLJs on the CI nights was likely influenced by nonuniform heating across the sloped terrain, which led to the uneven LLJ depth and contributed toward the wind veering with height through the creation of horizontal buoyancy gradients. These three CI events highlight the importance of assessing the full three-dimensional structure of the LLJ when forecasting nocturnal convection over the Great Plains.
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contributor author | Gebauer, Joshua G. | |
contributor author | Shapiro, Alan | |
contributor author | Fedorovich, Evgeni | |
contributor author | Klein, Petra | |
date accessioned | 2019-09-19T10:04:49Z | |
date available | 2019-09-19T10:04:49Z | |
date copyright | 6/28/2018 12:00:00 AM | |
date issued | 2018 | |
identifier other | mwr-d-18-0002.1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl1/handle/yetl/4261298 | |
description abstract | AbstractObservations from three nights of the Plains Elevated Convection at Night (PECAN) field campaign were used in conjunction with Rapid Refresh model forecasts to find the cause of north?south lines of convection, which initiated away from obvious surface boundaries. Such pristine convection initiation (CI) is relatively common during the warm season over the Great Plains of the United States. The observations and model forecasts revealed that all three nights had horizontally heterogeneous and veering-with-height low-level jets (LLJs) of nonuniform depth. The veering and heterogeneity were associated with convergence at the top-eastern edge of the LLJ, where moisture advection was also occurring. As time progressed, this upper region became saturated and, due to its placement above the capping inversion, formed moist absolutely unstable layers, from which the convergence helped initiate elevated convection. The structure of the LLJs on the CI nights was likely influenced by nonuniform heating across the sloped terrain, which led to the uneven LLJ depth and contributed toward the wind veering with height through the creation of horizontal buoyancy gradients. These three CI events highlight the importance of assessing the full three-dimensional structure of the LLJ when forecasting nocturnal convection over the Great Plains. | |
publisher | American Meteorological Society | |
title | Convection Initiation Caused by Heterogeneous Low-Level Jets over the Great Plains | |
type | Journal Paper | |
journal volume | 146 | |
journal issue | 8 | |
journal title | Monthly Weather Review | |
identifier doi | 10.1175/MWR-D-18-0002.1 | |
journal fristpage | 2615 | |
journal lastpage | 2637 | |
tree | Monthly Weather Review:;2018:;volume 146:;issue 008 | |
contenttype | Fulltext |