DOI: 10.5061/dryad.44j0zpcj2
title: Simulation datasets for: Intense surface winds from gravity wave breaking in simulations of a destructive macroburst

description: Shortly after 0600 UTC (midnight local time) 9 June 2020, a convective
 line produced severe winds across parts of northeast Colorado that caused
 extensive damage, especially in the town of Akron. High-resolution
 observations showed gusts exceeding 50 m s−1, accompanied by extremely
 large pressure fluctuations, including a 5-hPa pressure surge in 19 s
 immediately following the strongest winds and a 15-hPa pressure drop in
 the following 3 min. Numerical simulations of this event (using the WRF
 Model) and with horizontally homogeneous initial conditions (using Cloud
 Model 1) reveal that the severe winds in this event were associated with
 gravity wave dynamics. In a very stable postfrontal environment, elevated
 convection initiated and led to a long-lived gravity wave. Strong
 low-level vertical wind shear supported the amplification and eventual
 breaking of this wave, resulting in at least two sequential strong
 downbursts. This wave-breaking mechanism is different from the usual
 downburst mechanism associated with negative buoyancy resulting from
 latent cooling. The model output reproduces key features of the
 high-resolution observations, including similar convective structures,
 large temperature and pressure fluctuations, and intense near-surface wind
 speeds. The findings of this study reveal a series of previously
 unexplored mesoscale and storm-scale processes that can result in
 destructive winds. Significance Statement Downbursts of intense wind can
 produce significant damage, as was the case on 9 June 2020 in Akron,
 Colorado. Past research on downbursts has shown that they occur when
 raindrops, graupel, and hail in thunderstorms evaporate and melt, cooling
 the air and causing it to sink rapidly. In this research, we used
 numerical models of the atmosphere, along with high-resolution
 observations, to show that the Akron downburst was different. Unlike
 typical lines of thunderstorms, those responsible for the Akron macroburst
 produced a wave in the atmosphere, which broke, resulting in rapidly
 sinking air and severe surface winds.
description: This dataset includes the information required to reproduce the
 model simulations presented in the manuscript. This includes the namelist
 and initial and lateral boundary conditions for the WRF simulation, and
 the namelist and initial sounding for the CM1 simulation.
description: # Simulation datasets for "Intense surface winds from gravity wave
 breaking in simulations of a destructive macroburst" --- Included
 here are the files required to configure and reproduce the numerical
 simulations presented in this manuscript. (Full model output is not
 included owing to its large size.) The manuscript includes simulations
 from the Weather Research and Forecasting model, version 4.0.3
 () and Cloud Model 1
 (), version 20.1. ##
 Description of the Data and file structure For the WRF model, included are
 the 'namelist.input' configuration file, along with the
 'wrfinput' files (netCDF format) for domains 1 and 2 that
 contain the model initial conditions. Also included are the time series
 output (plain text) for the locations shown in the manuscript, along with
 the configuration file 'tslist' for outputting these time
 series. For the CM1 model, the 'namelist.input.cm1'
 configuration file and 'input_sounding' files are included,
 which can be used to initialize the model. The full fortran source code
 'onefile.F' is also included. ## Sharing/access Information
 Links to other publicly accessible locations of the data: N/A Was data
 derived from another source? No