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Mesoscale analysis of arc rainbands in a dry slot
Author(s) -
Browning K. A.,
Roberts N. M.
Publication year - 1999
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49712556118
Subject(s) - mesoscale meteorology , mesoscale convective system , rainband , geology , climatology , radiosonde , mesocyclone , meteorology , extratropical cyclone , cold front , radar , tropical cyclone , atmospheric sciences , doppler radar , geography , telecommunications , computer science
A series of almost concentric, are‐shaped narrow rainbands was observed travelling at 140 km h −1 and producing severe wind gusts over parts of England. Their structure and environment have been analysed using radar and satellite imagery, mesoscale‐model diagnostics, surface observations and additional rawinsonde ascents obtained during the Fronts and Atlantic Storm‐Track EXperiment (FASTEX). the multiple‐rainband event is shown to have been associated with part of a dry intrusion characterized by a mesoscale vortex/cold pool. the event occurred within the ‘dry slot’ region of a small frontal cyclone where the mesoscale pool of cold dry air was overrunning warm‐sector air. Continuous wind profiles from a UHF radar, together with a well‐located rawinsonde at the ‘epicentre’ of the arc rainbands, showed that the major anomaly in the cold pool was an area of locally stronger winds (>40 m s −1 ) at 800 hPa colocated with the temperature minimum at that level. the observed orientation of the rainbands is explained in terms of the cold‐frontal structure at this level triggering ascent of the underlying warm moist air. the multiple nature of the arc rainbands remains unexplained; the possibilities of mesoscale gravity waves and conditional symmetric instability are both considered.