Supporting data for: A big chill: Examining an extremely sharp cold front from three perspectives
Data files
Apr 07, 2025 version files 2.04 GB
-
cys.d02.TS
3 MB
-
GLY04.d02.TS
3 MB
-
namelist.input
7.96 KB
-
README.md
5.53 KB
-
STN01.d02.TS
3 MB
-
tslist
3.52 KB
-
usda_akron_21dec22_share.csv
21.01 MB
-
wrfbdy_d01
382.55 MB
-
wrfinput_d01
575.65 MB
-
wrfinput_d02
1.05 GB
Abstract
On 21–22 December 2022, an extremely strong cold front moved southward through the High Plains of the United States. The frontal passage was associated with rapid temperature decreases that rivaled or exceeded the largest that have been reported in the literature. In many locations in Wyoming and Colorado, the temperature dropped from above freezing to below zero Fahrenheit (below –17.8°C) in a few hours. High-resolution observations from an eddy covariance tower in Akron, Colorado revealed a 2-m air temperature drop of 13.8°C in 10 s and 15.4°C in 30 s, showing that this front effectively represented a discontinuity in temperature. Operational forecast models indicated the potential for a strong cold front up to 9 days in advance, but displayed considerable run-to-run variability and uncertainty in the timing of frontal passage. Forecasts from data-driven weather prediction models (trained using deep learning) were generally more accurate than those from physics-based models in terms of the timing and location of the front, but did not represent the extreme temperature gradients that occurred. Short-term operational model forecasts provided a detailed depiction of the front, but predicted the frontal passage to be slightly slower and weaker than was observed. A high-resolution numerical simulation reveals a frontal structure akin to a density current with a hydraulic head, consistent with past observations of intense cold fronts to the east of the Rocky Mountains. In total, this study provides climatological context and a detailed picture of forecast performance and physical processes for one of the sharpest cold fronts in U.S. records.
Supporting data for: A big chill: examining an extremely sharp cold front from three perspectives
https://doi.org/10.5061/dryad.xksn02vrv
Description of the data and file structure
Included here are the files required to configure and reproduce the numerical simulation presented in this manuscript. (Full model output is not included owing to its large size.) The manuscript includes analysis of a simulation from the Weather Research and Forecasting model, version 4.3. The WRF model is available from the National Center for Atmospheric Research at: https://www.mmm.ucar.edu/models/wrf
Also included is a file with the observations from the Akron, Colorado eddy covariance tower presented in the manuscript. Additional parameters, such as the wind direction using meteorological convention, and air temperature derived from the sonic temperature, are included along with the standard parameters described in the LI-COR documentation.
Files and variables
File: STN01.d02.TS
Description: WRF model time series output at the grid point nearest to the CoAgMET station in Stratton, Colorado. The specific latitude/longitude location of each of these time series is given in the first line the file.
File: GLY04.d02.TS
Description: WRF model time series output at the grid point nearest to the CoAgMET station in Greeley, Colorado. The specific latitude/longitude location of each of these time series is given in the first line the file.
File: cys.d02.TS
Description: WRF model time series output at the grid point nearest to the ASOS in Cheyenne, Wyoming. The specific latitude/longitude location of each of these time series is given in the first line the file.
File: namelist.input
Description: WRF model configuration file.
File: wrfbdy_d01
Description: lateral boundary conditions for the WRF model in the standard WRF netCDF format (domain 1).
File: wrfinput_d01
Description: initial conditions for the WRF model in the standard WRF netCDF format (domain 1).
File: wrfinput_d02
Description: initial conditions for the WRF model in the standard WRF netCDF format (domain 2).
File: usda_akron_21dec22_share.csv
Description: Observations from the USDA eddy covariance tower located near Akron, Colorado.
Variables
- TIMESTAMP: time stamp
- Temperature (C): temperature from the thermistor
- Pressure (kPa): pressure
- U (m/s): component of the wind, with positive being 2 degrees west of north
- V (m/s): component of the wind with positive values 90 degrees counter-clockwise from the U component
- W (m/s): vertical wind component
- T (C): sonic temperature
- wspd: wind speed (calculated) in m/s
- wdir_corr: wind direction, corrected to meteorological convention where a wind from the north is zero degrees.
- uuu_corr: u-component of the wind, where positive is pointed to the east
- vvv_corr: v-component of the wind, where positive is pointed to the north
- spfh: specific humidity (kg/kg)
- Ta_sonic: air temperature from the sonic anemometer, calculated as Ta = Ts/(1+0.51q), where q is the specific humidity
File: tslist
Description: WRF “tslist” file, with a listing of the locations where time series are recorded at each model timestep, for the nearest model grid point.
Code/software
The format of the WRF time series (.TS) files is described at https://github.com/wrf-model/WRF/blob/master/run/README.tslist. The specific latitude/longitude location of each of these time series is given in the first line of each file. The “tslist” configuration file that describes the latitude/longitude of each location (also described at the WRF model link above) is also included. These are plain text files that can be viewed or manipulated with any text editor, and can also be imported to tools like Excel using “from text” or using R or python/pandas “read.table” functions.
WRF-formatted netCDF files can be viewed using tools like ncview, or read and analyzed in xarray for python.
The WRF namelist.input file is a plain text file that can be viewed or manipulated with any text editor (e.g., Linux less command, Nano, Vim, Text Editor). The format follows the WRF model specifications.
usda_akron_21dec22_share.csv is a comma-separated text file that can be imported using tools like Excel, R, or the pandas package in python.
A github repository that includes jupyter notebooks used to prepare many of the figures in this manuscript is at: https://github.com/russ-schumacher/dec2022_coldfront/. In particular, the notebook wrf_hrrr_asos_tser_compare_loop.ipynb includes code for reading the WRF time series files, as well as output from the HRRR model and station observations, and plotting comparisons between them. The notebook akron_ec_tser_pub.ipynb includes code for reading and plotting the data from the Akron eddy covariance tower in the file usda_akron_21dec22_share.csv.
This dataset includes the information required to reproduce the model simulation presented in the manuscript. This includes the namelist and initial and lateral boundary conditions for the WRF model simulation. Time series output at each model timestep is also included for the locations shown in the manuscript.
Also included are observations from the eddy covariance tower at the USDA research facility Akron, Colorado, provided by David Poss of USDA.