A case study of the interaction of a mesoscale gravity wave with a mesoscale convective system

James H. Ruppert, Lance F. Bosart

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12 Scopus citations

Abstract

This study documents the high-amplitude mesoscale gravity wave (MGW) event of 7 March 2008 in which two MGWs strongly impacted the sensible weather over a large portion of the Southeast United States. These MGWs exhibited starkly contrasting character despite propagating within similar environments. The primary (i.e., long lived) MGW was manifest by a solitary wave of depression associated with rapid sinking motion and adiabatic warming, while the secondary (short lived) MGW was manifest by a solitary wave of elevation ("MGWEL"), dominated by rising motion and moist adiabatic cooling. Genesis of the primary MGW occurred as a strong cold front arrived at the foot of Mexico's high terrain and perturbed the appreciable overriding flow. The resulting gravity wave became ducted in the presence of a low-level frontal stable layer, and caused surface pressure falls up to ~4 hPa. The MGW later amplified as it became coupled with a stratiform precipitation system, which led to its evolution into an intense mesohigh-wake low couplet. This couplet propagated as a ducted MGW attached to a stratiform system for ̃12 h thereafter, and induced rapid surface pressure falls of ≥10 hPa (including a fall of 6.7 hPa in 10 min), rapid wind vector changes (e.g., 17ms-1 in 25 min), and high wind gusts (e.g., 20ms-1) across several states. MGWEL appeared within the remnants of a squall line, and was manifest by a sharp pressure ridge of ̃6 hPa with a narrow embedded rainband following the motion of a surface cold front. MGWEL bore resemblance to previously documented gravity waves formed by density currents propagating through stable environments.

Original languageEnglish (US)
Pages (from-to)1403-1429
Number of pages27
JournalMonthly Weather Review
Volume142
Issue number4
DOIs
StatePublished - Apr 2014

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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