Shikhov et al. (2025) Climatology and Formation Environments of Heavy Snowfall Events in the Ural Region (Russia)

Identification

• Journal: Atmosphere
• Year: 2025
• Date: 2025-12-08
• Authors: Andrey Shikhov, N. A. Kalinin, Евгения Владимировна Пищальникова
• DOI: 10.3390/atmos16121386

Research Groups

• Faculty of Geography, Perm State University, Perm, Russia

Short Summary

This study provides the first comprehensive climatology and synoptic-scale environment analysis of hazardous heavy snowfall (HHS) events (≥20 mm 12 h−1) in the Ural region (1981–2025), revealing that 46% of events are linked to cyclones from the Caspian and Aral seas, leading to higher HHS frequency east of the Ural Mountains.

Objective

• To summarize the main characteristics of hazardous heavy snowfall (HHS) events (≥20 mm 12 h−1) and their related synoptic-scale environments in the Ural region between 1981 and 2025.
• To present the climatology and synoptic-scale environments of snowfall extremes in the Ural region, using ground-based observations and ERA5 reanalysis data.

Study Configuration

• Spatial Scale: Ural region, Russia, encompassing the Perm, Sverdlovsk, Chelyabinsk, and Kurgan regions, including the Ural Mountains, East European Plain, and West Siberian Plain.
• Temporal Scale: 1981–2025 (45 years).

Methodology and Data

• Models used:
  • NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model (for 72 h backward trajectories)
  • NCEP/NCAR reanalysis (for HYSPLIT, 1984–2005)
  • Global Data Assimilation System (GDAS) (for HYSPLIT, 2006–present)
• Data sources:
  • Ground-based observations from Roshydromet weather stations (87 stations, with 36 reference stations providing data for the entire period)
  • ERA5 reanalysis data (daily snowfall amount, air temperature at 850 hPa (T850), total precipitable water (PW), 700-hPa geopotential height (H700), pressure at mean sea level (MSLP))
  • Annual reports on hazardous weather events (HWE) and monthly reviews of HWE
  • Media news (damage reports)
  • Database of windthrow events in the forest zone of Russia
  • Worldclim 2.0 dataset (mean annual air temperature, annual precipitation)
  • ERA5-Land data (snow water equivalent)

Main Results

• A dataset of 116 HHS reports, associated with 56 distinct HHS events, was compiled. 12-hourly snowfall intensities ranged from 20 mm to 47.6 mm, with a mean of 25.4 mm and a median of 23.1 mm.
• The strongest 12 h snowfall was 47.6 mm (wet snow with rain) on 6 June 1995; the strongest pure snowfall was 38.8 mm on 25–26 April 2014.
• 24-hourly snowfall amounts ranged from 20 mm to 70.9 mm, with a mean of 35.8 mm and a median of 36.3 mm.
• Over 90% of HHS events occurred when 2 m air temperatures ranged from -5 °C to 1 °C.
• No statistically significant trend was found in the frequency of HHS events or the annual maximum daily snowfall (Smax_annual) over the study period. However, the frequency of the most damaging late spring and early autumn snowfalls has decreased.
• The seasonal distribution of HHS events shows two pronounced peaks in April–May and October.
• The spatial distribution of HHS events does not correspond to the mean annual snowfall (Sannualmean); most HHS events occurred east of the Ural Mountains, where Sannualmean is lower.
• 47.5% of HHS reports are related to the "S type" (southern advection from the Caspian and Aral Seas), which explains the higher frequency of HHS events in the eastern part of the region.
• "NW-type" events (Arctic intrusions from the Kara Sea) are the least frequent but most damaging, occurring in late spring/early summer with the highest average snowfall amounts (mean 29.6 mm 12 h−1).
• Compound extremes (heavy snowfall with severe winds ≥25 m s−1 or wet snow accumulation ≥50 mm diameter) are rare but cause significant damage. The 6 June 1995 snowstorm, an NW-type event, involved 47 mm 12 h−1 snowfall, 26 m s−1 wind gusts, and 190 mm wet snow accumulation, causing USD 32.6 million in damage and destroying 19,600 hectares of forest.

Contributions

• Provides the first comprehensive climatology and synoptic-scale environment analysis of hazardous heavy snowfall (HHS) events for the entire Ural region (1981–2025).
• Compiles a unique dataset of 116 HHS reports and 56 events by integrating ground observations, reanalysis data, scientific literature, and media reports.
• Classifies HHS events into five types based on HYSPLIT-based backward trajectories, establishing a link between air mass origin and the spatial and seasonal distribution patterns of these events.
• Conducts a detailed composite analysis of synoptic-scale environments (H700, MSLP, PW, T850) for each HHS type, explaining regional differences in HHS occurrence.
• Summarizes damage characteristics associated with HHS events in the Ural region for the first time, highlighting the significant impact of compound extremes and late spring/early autumn events.
• Demonstrates that the spatial distribution of HHS events is primarily determined by synoptic-scale environments rather than the mean annual snowfall amount.

Funding

• Russian Scientific Foundation, Project Number 24-27-00054

Citation

@article{Shikhov2025Climatology,
  author = {Shikhov, Andrey and Kalinin, N. A. and Пищальникова, Евгения Владимировна},
  title = {Climatology and Formation Environments of Heavy Snowfall Events in the Ural Region (Russia)},
  journal = {Atmosphere},
  year = {2025},
  doi = {10.3390/atmos16121386},
  url = {https://doi.org/10.3390/atmos16121386}
}