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Environmental Influences on Deep Convective Upscale Growth Rate in Central Argentina From a Convection‐Permitting Simulation.

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Title: Environmental Influences on Deep Convective Upscale Growth Rate in Central Argentina From a Convection‐Permitting Simulation.
Authors: Sasaki, Clayton R. S.1 (AUTHOR), Rowe, Angela K.2 (AUTHOR) akrowe@wisc.edu, McMurdie, Lynn A.1 (AUTHOR), Varble, Adam C.3 (AUTHOR), Zhang, Zhixiao4 (AUTHOR)
Source: Journal of Geophysical Research. Atmospheres. 1/16/2026, Vol. 131 Issue 1, p1-19. 19p.
Subject Terms: *Climate change, Mesoscale convective complexes, Vertical wind shear, Numerical weather forecasting, Atmospheric physics, Natural heat convection
Geographic Terms: Argentina
Abstract: This study uses a convection‐permitting model simulation to describe the environmental conditions under which convective upscale growth occurs in central Argentina, particularly examining environmental parameters when deep convection initially forms that could differentiate the rate of initial upscale growth. Simulated mesoscale convective systems (MCSs) are separated into slow and rapid growth by the rate of spatial growth from convection initiation until reaching the MCS scale. A low‐level jet (LLJ) is found more frequently near the deep convection that experiences rapid growth to an MCS, but its presence alone is not predictive of rapid growth. Using spatially‐averaged parameters, we find that rapid growth to MCSs also occurs in environments that are significantly more thermodynamically favorable with greater low‐level moisture and instability. Fewer significant differences are found in the kinematic environment with only the 0–2 km vertical wind shear magnitude being significantly larger for rapid growth MCSs compared to slow growth MCSs, potentially related to LLJs often peaking near this height. When focusing only on MCSs with the slowest and fastest growth rates, elevated‐layer shear is significantly smaller for very rapid growth MCSs, suggesting elevated‐layer shear may help discriminate between the upper and lower bounds of growth rate. Finally, when upscale growth occurs near the Sierras de Córdoba (SDC) with a LLJ present, rapid growth is also supported by favorable wind shear orientation. However, this does not hold for upscale growth occurring away from the SDC, highlighting the importance of interpreting shear direction relative to the orientation of features initiating deep convection. Plain Language Summary: Understanding the environments that support spatial growth of storms is crucial for predicting their impacts. This study uses a 6.5‐month‐long high‐resolution model simulation to examine the environments of simulated storm systems separated based on their rate of spatial growth. Results show that environments with a faster growth rate have greater moisture and instability. While vertical wind shear, defined as the change in wind speed and/or direction with height, is a well‐known factor in storm organization, its magnitude does not vary strongly with growth rate when shear is averaged over a large area, likely due to the large spread in values present. However, the direction of wind shear is likely an important factor in the rate of growth, and faster spatial growth is found for storms growing near the mountains when a favorable shear direction (parallel to the mountain range) is present. A low‐level jet, an area of stronger wind speeds elevated off of the surface, is found more frequently in environments with a faster growth rate and is likely an important mechanism that facilitates differences in thermodynamics and wind shear. Key Points: Using a seasonal convection‐permitting simulation, environments are compared for storms with slow and rapid spatial growth to mesoscale convective systems (MCS)Rapid growth is favored in environments with greater low‐level moisture and instability, likely related to the presence of a low‐level jet (LLJ)Favorable vertical wind shear orientation when a LLJ is present near the mountains likely also supports rapid MCS growth [ABSTRACT FROM AUTHOR]
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Database: GreenFILE
Description
Abstract:This study uses a convection‐permitting model simulation to describe the environmental conditions under which convective upscale growth occurs in central Argentina, particularly examining environmental parameters when deep convection initially forms that could differentiate the rate of initial upscale growth. Simulated mesoscale convective systems (MCSs) are separated into slow and rapid growth by the rate of spatial growth from convection initiation until reaching the MCS scale. A low‐level jet (LLJ) is found more frequently near the deep convection that experiences rapid growth to an MCS, but its presence alone is not predictive of rapid growth. Using spatially‐averaged parameters, we find that rapid growth to MCSs also occurs in environments that are significantly more thermodynamically favorable with greater low‐level moisture and instability. Fewer significant differences are found in the kinematic environment with only the 0–2 km vertical wind shear magnitude being significantly larger for rapid growth MCSs compared to slow growth MCSs, potentially related to LLJs often peaking near this height. When focusing only on MCSs with the slowest and fastest growth rates, elevated‐layer shear is significantly smaller for very rapid growth MCSs, suggesting elevated‐layer shear may help discriminate between the upper and lower bounds of growth rate. Finally, when upscale growth occurs near the Sierras de Córdoba (SDC) with a LLJ present, rapid growth is also supported by favorable wind shear orientation. However, this does not hold for upscale growth occurring away from the SDC, highlighting the importance of interpreting shear direction relative to the orientation of features initiating deep convection. Plain Language Summary: Understanding the environments that support spatial growth of storms is crucial for predicting their impacts. This study uses a 6.5‐month‐long high‐resolution model simulation to examine the environments of simulated storm systems separated based on their rate of spatial growth. Results show that environments with a faster growth rate have greater moisture and instability. While vertical wind shear, defined as the change in wind speed and/or direction with height, is a well‐known factor in storm organization, its magnitude does not vary strongly with growth rate when shear is averaged over a large area, likely due to the large spread in values present. However, the direction of wind shear is likely an important factor in the rate of growth, and faster spatial growth is found for storms growing near the mountains when a favorable shear direction (parallel to the mountain range) is present. A low‐level jet, an area of stronger wind speeds elevated off of the surface, is found more frequently in environments with a faster growth rate and is likely an important mechanism that facilitates differences in thermodynamics and wind shear. Key Points: Using a seasonal convection‐permitting simulation, environments are compared for storms with slow and rapid spatial growth to mesoscale convective systems (MCS)Rapid growth is favored in environments with greater low‐level moisture and instability, likely related to the presence of a low‐level jet (LLJ)Favorable vertical wind shear orientation when a LLJ is present near the mountains likely also supports rapid MCS growth [ABSTRACT FROM AUTHOR]
ISSN:2169897X
DOI:10.1029/2025JD044251