Morphology and evolution of cold‐frontal misocyclones

• Published in: Quarterly journal of the Royal Meteorological Society 2009-01, Vol.135 (639), p.381-393
• Main Authors: Smart, D. J., Browning, K. A.
• Format: Article
• Language: English
• Subjects: cold front; Earth, ocean, space; Exact sciences and technology; External geophysics; gravity current; Meteorology; NWP; Physics of the high neutral atmosphere; severe winds; tornadogenesis
• ISSN: 0035-9009; 1477-870X
• DOI: 10.1002/qj.399

A numerical simulation of an intense, narrow cold‐frontal rain band (NCFR) is presented. This front was associated with localized wind damage as it moved eastwards across the United Kingdom on 24 September 2007. The model used was the operational and research Weather Research and Forecasting‐‐Advanced Research (WRF‐‐ARW) mesoscale model, initialized with Global Forecast System (GFS) operational model output data. The simulation produced a front strongly resembling that seen in radar imagery and conforming to previous studies and conceptual models of the ana‐cold front. In the simulation, a strong surface horizontal wind‐speed maximum is located along the southern flank of a misocyclone; this is shown to be typical of a number that form along the front. Using trajectory analysis, descending cold air parcels, which originate in the rear inflow jet and accelerate within the circulation of the misocyclone, are identified as the origin of the strongest winds. In addition to the localized strong straight‐line winds, circumstantial evidence is presented for the possible occurrence of weak tornadogenesis. The results are discussed in relation to recent studies of NCFRs, squall lines and misocyclones. Copyright © 2009 Royal Meteorological Society