DOI: 10.5061/dryad.q573n5ts9
title: GFS Storm Precipitation and Trajectories, 2021

description: Operational forecast models are necessary for the prediction of weather
 events in real time. Verification of these models must be
 performed to assess model skill and areas in need of improvement,
 particularly with different types of weather events that may occur.
 Despite the devastating impacts that can be caused by tropical
 cyclones (TCs) that undergo extratropical transition (ET) and
 become post-tropical cyclones (PTCs), these storms have not been
 extensively studied in the context of short-term weather prediction. This
 study completes the first analysis of the Global Forecast System
 (GFS) and a pre-operational version of the newly operational Hurricane
 Analysis and Forecast System (HAFS) models in forecasting the occurrence
 of ET and the rainfall associated with ET storms in the North
 Atlantic basin. GFS’s skill exceeds that of HAFS in forecasting
 the occurrence of ET, but HAFS tends to have lower track and rain rate
 errors in the fully tropical phase of ET storms’ life cycles.
 Both models simulate rain rates that are often too high near the storm
 center and fail to capture the larger area of moderate rain rates that
 greatly contributes to total rainfall accumulation. The
 discrepancies in rain rates between the models and IMERG could be
 attributed to the models’ tendency to keep storms too intense and too
 compact with an overly strong warm core, even throughout the ET process.
description: The data that support the findings of this study are available at
 the following URLs: IMERG Final Run: https://gpm1.gesdisc.eosdis.nasa.gov/data/GPM_L3/GPM_3IMERGHH.06/ IBTrACS v4: https://www.ncdc.noaa.gov/ibtracs/index.php?name=ib-v4-access ERA5 reanalysis: https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=dataset GFS data was accessed from the UCAR Research Data Archive: https://doi.org/10.5065/D65Q4TSG TempestExtremes is publicly available on GitHub at:<br>https://github.com/ClimateGlobalChange/tempestextremes ExTraTrack software is available at https://github.com/zarzycki/ExTraTrack
description: # GFS Storm Precipitation and Trajectories, 2021
 [https://doi.org/10.5061/dryad.q573n5ts9](https://doi.org/10.5061/dryad.q573n5ts9) ## Description of the data and file structure This dataset contains the storm-related rainfall files from the GFS model runs from 2021 as well as the storm trajectories used in the associated manuscript. These files are generated by tracking the TC of interest in each operational simulation, including the extension of the TC trajectory into the post-tropical phase. Rainfall is then tracked using a 1 mm/hr threshold for identifying precipitation objects. The area over which to extract the storm-related rainfall is created by identifying the locations around the storm center where the geopotential height at 500 hPa (Z500) increases by 10 m from the value at the center of the storm (Z500 mask). Finally, the rainfall objects and the Z500 mask are overlaid, thus co-locating rainfall with its respective storm. The TC tracking, precipitation tracking, Z500 mask generation, and co-location are all accomplished using TempestExtremes. The extension of TC trajectories to include the post-tropical phase is done using ExTraTrack. The files named "`masked_precip_gfs_${DATE}*${STORM}ET_1MMHR.nc`" include only the precipitation related to the storm in the file name for the model run initialized at the time in the file name when using a 1 mm/hr threshold. These files include the ET phase of the storm life cycle, while the `xxx_TC_1MMHR.nc` files only include the TC phase of the storm life cycle. Files entitled "`traj``ET*${STORM}``${DATE}.txt`" include the storm trajectory information for the storm named in the file name for the model initialization time in the file name. Any files with the name "`traj_et_ERA5_${STORM}_avg`" are the observed storm trajectories extended to include the ET phase using ERA5 reanalysis. The "`masked***.nc`" files include precipitation in mm/hr, latitude, longitude, and time. This precipitation is filtered out so that only rainfall associated with the storm of interest is included. The "`traj_***`" files are in TempestExtremes/ExTraTrack format. The header line is in the format "start number_of_timesteps year_start month_start day_start hour_start". The rest of the lines are in the format "lon_index lat_index lon lat pressure wind blank year month day hour" The indices are unitless, latitude and longitude are in degrees, pressure is in Pa, wind in knots, then there's a blank column, and the date. ## Code/software While no special software is required for viewing this data, the following resources were used to create it: TempestExtremes: [https://github.com/ClimateGlobalChange/tempestextremes/tree/master](https://github.com/ClimateGlobalChange/tempestextremes/tree/master) ExTraTrack: [https://github.com/zarzycki/ExTraTrack](https://github.com/zarzycki/ExTraTrack) ## Access information Other publicly accessible locations of the data: * N/A Data was derived from the following sources: * IMERG Final Run: [https://gpm1.gesdisc.eosdis.nasa.gov/data/GPM_L3/GPM\\](https://gpm1.gesdisc.eosdis.nasa.gov/data/GPM_L3/GPM\\)\_ 3IMERGHH.06/. * IBTrACS v4: [https://www.ncdc.noaa.gov/ibtracs/index.php?name=ib-v4-access](https://www.ncdc.noaa.gov/ibtracs/index.php?name=ib-v4-access). * ERA5 reanalysis: [https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=](https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=) dataset. * GFS forecast archive available from NCAR Research Data Archive: [https://doi.org/10](https://doi.org/10). 5065/D65Q4TSG.