Large-Amplitude Gravity Waves as an Unclassified Type of Storm: Observations and Inferences from Three Decades of Synoptic Data Monitoring Applying Pattern Recognition

The hazardous weather associated with the passage of large-amplitude inertia gravity waves (IGW), particularly surface winds that may reach 20–30 m s^-1, constitute a storm by standard definition yet remain unclassified as such. Along with their relative rarity (~1–3 events per year in the conterminous USA), the lack of formal designation contributes to the IGW phenomenon remaining relatively obscure and poorly understood by most meteorologists and other operational warning personnel. Real-time high-temporal resolution observational networks (e.g. the USArray, MADIS, MesoWest) now facilitate detection and monitoring of IGW events in progress, and operational mesoscale and medium-range forecast models have successfully predicted several recent events. However, the uptake of this guidance by human forecasters appears to be limited. This limitation points to benefits that could potentially be derived by improving forecaster awareness through IGW classification as a storm type, and the development of algorithms to detect characteristic IGW signals in operational mesoscale model output. This presentation will build the case for a storm classification scheme, introducing case studies of large amplitude (6-15 hPa surface pressure change) IGWs identified in real-time over the past three decades using conventional synoptic meteorological observations, and propose a new model of their structure in the lower troposphere.