Observations of Mergers between Squall Lines and Isolated Supercell Thunderstorms
نویسندگان
چکیده
A set of 21 cases in which an isolated supercell merged with a squall line were identified and investigated using analyses from the Rapid Update Cycle (RUC) model, archived data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network, and severe storm reports. This analysis revealed two primary environments associated with these mergers: a weak synoptic forcing, weak to moderate shear environment (WF) and a strong synoptic forcing, strong shear environment (SF). These environments bear a strong resemblance to those identified for progressive (WF) and serial (SF) derechoes in past studies. Radar reflectivity data revealed a spectrum of storm evolution patterns that generally lead to the merged system organizing as a bow echo. At one extreme, observed exclusively in the WF environment, the entire squall line evolved into a large bow echo following the merger. At the other extreme, observed for several cases in the SF environment, a localized bowing segment developed embedded within the larger squall line. The remaining cases exhibited characteristics best described as a hybrid of these extremes. Storm rotation generally weakened and became concentrated in low levels following the merger, although the exact evolution differed between the two background environments. Finally, an analysis of storm reports revealed that hail reports were maximized premerger and severe wind reports postmerger in both environments, while the distribution of tornado reports varied. In the WF environment a larger fraction of tornado reports occurred postmerger, while tornado production was maximized premerger in the SF environment. This suggests an evolving severe weather threat during the course of the merger, the details of which depend on the background environment.
منابع مشابه
A comparison of the midlevel kinematic characteristics of a pair of supercell thunderstorms observed by airborne Doppler radar
The midlevel kinematic characteristics of two supercell thunderstorms observed during the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX), one tornadic and the other nontornadic, are compared using airborne pseudo-dualDoppler wind retrievals. The most significant difference between the two cases was that a midlevel rear-inflow jet was observed in the nontornadic superce...
متن کاملUse of Doppler Radar in Meteorological Observations
The U.S. IVeather Bureau has been experimenting with a radar operating on the Doppler principle t o dc%ermine whether apparatus of this type would detect and uniquely identify tornadoes. The principles of Doppler radar as applied to meteorology and results of recent experiment,s with equipment of this type are discussed. Calculations of anomalous wind speeds of 206 m.p.h. in a funnel cloud and ...
متن کاملComparison of Thunderstorm Simulations from WRF-NMM and WRF-ARW Models over East Indian Region
The thunderstorms are typical mesoscale systems dominated by intense convection. Mesoscale models are essential for the accurate prediction of such high-impact weather events. In the present study, an attempt has been made to compare the simulated results of three thunderstorm events using NMM and ARW model core of WRF system and validated the model results with observations. Both models perfor...
متن کاملThe tempest unmanned aircraft system for in situ observations of tornadic supercells: Design and VORTEX2 flight results
This paper reports results from field deployments of the Tempest Unmanned Aircraft System, the first of its kind of unmanned aircraft system designed to perform in situ sampling of supercell thunderstorms, including those that produce tornadoes. A description of the critical system components, consisting of the unmanned aircraft, ground support vehicles, communications network, and custom softw...
متن کامل