DOI: 10.5061/dryad.wpzgmsbxw
title: HAFS Storm Precipitation and Trajectories, 2020 and 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: This dataset includes the data from HAFS in the manuscript
 "Verification of Operational Forecast Models in cases of
 Extratropical Transition of North Atlantic Hurricanes" for the
 analysis of precipitation throughout the entire TC life cycle.
 This dataset enables the analysis of precipitation throughout the
 entire tropical cyclone (TC) life cycle, including points during and after
 extratropical transition (ET) occurs. The ET process enables TCs to lose
 their tropical characteristics and be sustained by midlatitude
 forcing. The files beginning with
 "traj_**********" are trajectories for the entire TC and PTC
 life cycle. TCs are first tracked with TempestExtremes, and these files
 are the TC trajectories extended using ExTraTrack to include all points
 during and after ET occurs. Further information about the contents of
 these files can be found here: https://github.com/zarzycki/ExTraTrack.
 Finally, the netCDF files (beginning in "masked" and ending in
 ".nc") contain the isolated TC and PTC precipitation that
 exceeds the 95th percentile threshold for the model simulations. The 95th
 percentile varies by location and is calculated from all days, regardless
 of the presence of rainfall or not, for each set of simulations-
 historical and future. Precipitation exceeding the 95th percentile is
 tracked using TempestExtremes, then co-located with TCs and PTCs using a
 dynamical radius calculated around the trajectories included in this
 dataset. A full description of the methods can be found in the full
 manuscript.
description: # HAFS Storm Precipitation and Trajectories, 2020 and 2021
 [https://doi.org/10.5061/dryad.wpzgmsbxw](https://doi.org/10.5061/dryad.wpzgmsbxw) ## Description of the data and file structure This dataset contains the storm-related rainfall and trajectory files from the HAFS model runs 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_hafs_${DATE}*${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. * HAFS data provided to Bower by Bin Liu, Zhan Zhang, and Matthew Green (NOAA EMC and WPC).