Mesoscale aspects of a dry intrusion within a vigorous cyclone

摘要: The results of a diagnostic study using radar and satellite imagery, together with surface reports output from regional mesoscale models, are presented for an occasion rapidly deepening cyclone that crossed the British Isles. shows how air descended near-tropopause level in form dry intrusions which appeared to overrun parts warm conveyor belt ahead cold front. One is analysed detail, because it thought have led large changes were observed character wide frontal rain band: some places precipitation was entirely suppressed, whilst other became convective, tornadic squall line developing. Although effect intrusion seen most clearly distribution as determined by radar, approach also detected water-vapour foreshadowed model forecasts. model, despite limitations, reproduced many features. It provided insight into detailed behaviour associated line. showed characterized filament high potential vorticity (PV) extruded lower part region PV near low tropopause. anomaly plunged within kilometre where overran belt. relatively wet-bulb temperature, θ w , instability air. itself not only but separate strip generated locally, mainly condensation. quality mesoscale-model simulation gives grounds optimism such models capable principle predicting severe weather events when, this case, they orchestrated resolved larger-scale dynamics