Wiles et al. (2026) Multiscale Dynamics Organizing Heavy Precipitation During Tropical Cyclone Hilary’s (2023) Remnant Passage over the Southwestern U.S.

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Identification

• Journal: Atmosphere
• Year: 2026
• Date: 2026-01-14
• Authors: Jackson T. Wiles, Michael L. Kaplan, Yuh-Lang Lin
• DOI: 10.3390/atmos17010082

Research Groups

Not explicitly stated in the provided text.

Short Summary

The study used the WRF model to simulate Tropical Cyclone Hilary's (2023) remnant passage over the southwestern United States, revealing that differential surface heating induced a mesoscale mid-level jet that transported tropical moisture over 1000 km, causing anomalous flooding in an arid western plateau.

Objective

• To simulate the synoptic to mesoscale evolving atmosphere of Tropical Cyclone (TC) Hilary’s (2023) remnant passage over the southwestern United States.
• To extensively study the atmospheric dynamic processes conducive to precursor rain events, specifically determining the effects of mid-level jetogenesis.
• To study the dynamics of mesoscale processes related to the interaction of TC Hilary over the complex topography of the western United States using sensitivity simulations.

Study Configuration

• Spatial Scale: Synoptic to mesoscale, southwestern United States, western United States complex topography; nested 2 km × 2 km grid for mesoscale processes; moisture transport over 1000 km.
• Temporal Scale: Tropical Cyclone Hilary’s (2023) remnant passage.

Methodology and Data

• Models used: Weather Research and Forecasting Model (WRF-ARW) version 4.5.
• Data sources: Not explicitly stated in the provided text.

Main Results

• Differential surface heating between the cloudy California coast and clear/elevated Great Basin plateau profoundly impacted the lower-mid-tropospheric mass field, resulting in mid-level jetogenesis.
• Diagnostic analyses of ageostrophic flow supported the importance of both isallobaric and inertial advective forcing of the mid-level jetogenesis in response to differential surface sensible heating.
• This ageostrophic mesoscale jet ultimately transported tropical moisture in multiple plumes more than 1000 km poleward beyond the location of the extratropical transition of the storm.
• This moisture transport resulted in anomalous flooding precipitation within a massive arid western plateau.

Contributions

• Identified differential surface heating as a critical mechanism for mid-level jetogenesis during tropical cyclone remnant passages over complex topography.
• Elucidated the role of both isallobaric and inertial advective forcing in the development of this mid-level jet.
• Demonstrated how this ageostrophic mesoscale jet can transport tropical moisture over vast distances (more than 1000 km) into arid regions, leading to anomalous and severe precipitation events.
• Provided new insights into the complex atmospheric dynamics governing the interaction of tropical cyclone remnants with the topography of the western United States.

Funding

Not explicitly stated in the provided text.

Citation

@article{Wiles2026Multiscale,
  author = {Wiles, Jackson T. and Kaplan, Michael L. and Lin, Yuh-Lang},
  title = {Multiscale Dynamics Organizing Heavy Precipitation During Tropical Cyclone Hilary’s (2023) Remnant Passage over the Southwestern U.S.},
  journal = {Atmosphere},
  year = {2026},
  doi = {10.3390/atmos17010082},
  url = {https://doi.org/10.3390/atmos17010082}
}