DOI: 10.13012/b2idb-3906187_v2
title: Radar analyzed quasi-linear convective system mesovortices during the Propagation, Evolution, and Rotation in Linear Storms (PERiLS) Project

description: This is a collection of 31 quasi-linear convective system (QLCS) mesovortices (MVs) that were first manually identified and analyzed using the lowest elevation scan of the nearest relevant Weather Surveillance Radar–1988 Doppler (WSR-88D) during the two years (springs of 2022 and 2023) of the Propagation, Evolution, and Rotation in Linear Storms (PERiLS) field campaign. This analysis was completed using the Gibson Ridge radar-viewing software (GR2Analyst). Throughout the two years of PERiLS, a total of nine intensive observing periods (IOPs) occurred (see https://catalog.eol.ucar.edu/perils_2022/missions and https://catalog.eol.ucar.edu/perils_2023/missions for exact IOP dates/times). However, only six of these IOPs (specifically, IOPs 2, 3, and 4 from both years) are included in this dataset. The inclusion criteria were based on the presence of strictly QLCS MVs that from a cursory analysis were within the C-band On Wheels (COW) domain, one of the research radars deployed in the field for the PERiLS project. The 31 QLCS MVs identified using WSR-88D data were also examined using data from the COW radar (using Solo3 software). The lowest elevation angle was not always useable in the COW data, and sometimes the second lowest elevation angle was used. Further details on how MVs were identified are provided below, and a very detailed methodology is published in Blind-Doskocil et al. (2025). 

Each MV had to be produced by a QLCS, defined as a continuous area of 35 dBZ radar reflectivity over at least 100 km when viewed from the lowest elevation scan. The MVs analyzed also had to pass through/near the COW’s domain at some point during their lifetimes to allow for additional analysis using the COW data. Tornadic (TOR), wind-damaging (WD), and non-damaging (ND) MVs were analyzed over their entire lifetime and subsequently during the pretornadic, predamaging (wind damage), and prewarning phase (classified altogether as the prephase) of each MV. The prephase MVs were classified based on the first damage report or lack thereof associated with them. ND MVs were ones that usually had a tornado warning placed on them (all but one case) but did not produce any damage and persisted for five or more radar scans; this was done to target the strongest MVs that forecasters thought could be tornadic. 

The QLCS MVs were identified using objective criteria, which included the existence of a circulation with a maximum differential velocity (dV; i.e., the difference between the maximum outbound and minimum inbound velocities at a constant range) of at least 20 kt over a distance ≤ 7 km. The following radar-based characteristics were catalogued for each QLCS MV at the lowest elevation angle of the nearest WSR-88D: latitude and longitude locations of the MV, the genesis to decay time of the MV, the maximum dV across the MV, the maximum rotational velocity (Vrot; i.e., dV divided by two), diameter of the MV, the range from the radar of the MV center, and the height above radar level of the MV center. 

In the Excel workbook titled “nexrad_analyzed_mvs_perils_illinois_data_bank”, there are a total of 36 sheets. 31 of the 36 sheets are for each MV that was examined. The 31 MV sheets that were used to calculate MV statistics are labeled following the convention 'mv#_iop#_qlcs'. ‘mv#’ is the unique number that was assigned to each MV for clear identification, 'iop#' is the IOP in which the MV occurred, 'qlcs' denotes that the MV was produced by a QLCS, and the 2023 IOPs are denoted by ‘_2023’ after ‘qlcs’ in the sheet name. In these sheets, there are notes on what was visually seen in the radar data, damage associated with each MV (using the National Centers for Environmental Information (NCEI) database), and the characteristics of the MV at each time step of its lifetime. The yellow rows in each of the sheets indicate the last row of data included in the prephase statistics. The orange boxes in the notes column indicate any reports that were in NCEI but not in GR2Analyst. There are also sheets that examine pretornadic and predamaging diameter trends; box and whisker plot statistics of the overall characteristics of the different types of MVs; and the overall characteristics of each MV, with one Excel sheet (‘combined_qlcs_mvs’) examining the characteristics of each MV over its entire lifetime and one Excel sheet (‘combined_qlcs_mvs_before_report’) examining the characteristics of each MV before it first produced damage or had a tornado warning placed on it. 

In the Excel workbook titled “cow_analyzed_mvs_perils_illinois_data_bank”, there are a total of 33 sheets. 31 of the 33 sheets are for each MV that was examined, with a similar naming convention to those analyzed using WSR-88D data. The data documented in each sheet is also similar to that in the WSR-88D sheets. Due to the very tedious and time-consuming nature of analyzing radar data manually, we mainly focused on cataloging only the times where the MVs were detectable in the COW data during the prephase. In the WSR-88D data, we examined the MVs over their entire lifetimes and during their prephases. Not all the MVs analyzed in the WSR-88D data ended up being detectable in the COW data, and we focused on comparing the prephase MVs in the COW data and WSR-88D data. Therefore, there are sheets that are missing values and note that the MV was not in the COW’s domain, not detectable during the prephase, only focused on cataloging the prephase, etc. There are also sheets that examine characteristics of each MV during the prephase (‘combined_qlcs_mvs_before_report’) and box and whisker plot statistics of the prephase characteristics of the MVs (‘box_whisker_stats).