Singhai et al. (2026) Conditional Weather Regimes and Moisture Pathways Associated With Summer Rainfall Over the Southeastern United States

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: International Journal of Climatology
• Year: 2026
• Date: 2026-11-02
• Authors: Priyanshi Singhai, Kathy Pegion, Akintomide A. Akinsanola, Bohar Singh, Thierry N. Taguela
• DOI: 10.1002/joc.70659

Research Groups

Not specified in the provided abstract.

Short Summary

This study identifies four distinct conditional weather regimes responsible for persistent summer rainfall over the southeastern United States (SEUS) from 1979 to 2023. It reveals that similar regional wet conditions can arise from fundamentally different large-scale atmospheric circulation and moisture transport configurations.

Objective

• To examine the distinct large-scale circulation configurations and associated moisture pathways that lead to persistent summer rainfall over the southeastern United States (SEUS).

Study Configuration

• Spatial Scale: Southeastern United States (SEUS), North Atlantic, North Pacific, North America.
• Temporal Scale: Summer season, 1979–2023, with persistent wet periods identified from 5-day mean rainfall anomalies.

Methodology and Data

• Models used: Rossby wave source and wave activity flux diagnostics.
• Data sources: 5-day mean rainfall anomalies and 850- and 200-hPa geopotential height anomalies (likely derived from reanalysis or observational data).

Main Results

• Four distinct conditional regimes (CRs) were identified, each characterized by unique coupled lower- and upper-tropospheric circulation anomalies.
• CR A exhibited a western ridge of the North Atlantic Subtropical High (NASH) located farther west, near 85° W. CR B, CR C, and CR D had NASH ridge locations clustered near 80° W and 26°–27° N.
• In CR A and CR B, an anomalous ridge along the northern flank of the NASH was associated with stronger zonal moisture convergence, which was the dominant contributor to net moisture convergence over the SEUS.
• In contrast, CR C and CR D showed a weaker or absent ridge-like anomaly, reduced zonal convergence, and a relatively more important meridional moisture contribution.
• All four regimes were characterized by tropospheric ascent over the SEUS, indicating rainfall-supporting vertical motion.
• Regime-dependent upper-level wave environments were observed across the North Pacific and North America, with CR A displaying the clearest trans-Pacific wave-activity pathway.

Contributions

• Reveals distinct circulation–moisture pathways that lead to persistent summer rainfall over the SEUS.
• Underscores that similar regional wet states can originate from fundamentally different large-scale dynamical configurations.
• Introduces a conditional weather-regime framework for analyzing persistent wet periods.

Funding

Not specified in the provided abstract.

Citation

@article{Singhai2026Conditional,
  author = {Singhai, Priyanshi and Pegion, Kathy and Akinsanola, Akintomide A. and Singh, Bohar and Taguela, Thierry N.},
  title = {Conditional Weather Regimes and Moisture Pathways Associated With Summer Rainfall Over the Southeastern United States},
  journal = {International Journal of Climatology},
  year = {2026},
  doi = {10.1002/joc.70659},
  url = {https://doi.org/10.1002/joc.70659}
}