Convection-Allowing and Convection-Parameterizing Ensemble Forecasts of a Mesoscale Convective Vortex and Associated Severe Weather Environment

被引:53
作者
Clark, Adam J. [1 ]
Gallus, William A., Jr. [1 ]
Xue, Ming [2 ,3 ]
Kong, Fanyou [3 ]
机构
[1] Iowa State Univ, Dept Geol & Atmospher Sci, Ames, IA USA
[2] Univ Oklahoma, Sch Meteorol, Norman, OK 73019 USA
[3] Univ Oklahoma, Ctr Anal & Predict Storms, Norman, OK 73019 USA
关键词
WARM-SEASON PRECIPITATION; LIVED MESOCONVECTIVE VORTICES; TORNADIC THUNDERSTORM SYSTEM; PART II; EXPLICIT FORECASTS; ADJUSTMENT SCHEME; JOHNSTOWN FLOOD; MODEL PHYSICS; CORE VORTEX; ETA-MODEL;
D O I
10.1175/2010WAF2222390.1
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
An analysis of a regional severe weather outbreak that was related to a mesoscale convective vortex (MCV) is performed. The MCV-spawning mesoscale convection system (MCS) formed in northwest Kansas along the southern periphery of a large cutoff 500-hPa low centered over western South Dakota. As the MCS propagated into eastern Kansas during the early morning of 1 June 2007, an MCV that became evident from multiple data sources [e. g., Weather Surveillance Radar-1988 Doppler (WSR-88D) network, visible satellite imagery, wind-profiler data, Rapid Update Cycle 1-hourly analyses] tracked through northwest Missouri and central Iowa and manifested itself as a well-defined midlevel short-wave trough. Downstream of the MCV in southeast Iowa and northwest Illinois, southwesterly 500-hPa winds increased to around 25 m s(-1) over an area with southeasterly surface winds and 500-1500 J kg(-1) of surface-based convective available potential energy (CAPE), creating a favorable environment for severe weather. In the favorable region, multiple tornadoes occurred, including one rated as a category 3 storm on the enhanced Fujita scale (EF3) that caused considerable damage. In the analysis, emphasis is placed on the role of the MCV in leading to a favorable environment for severe weather. In addition, convection-allowing forecasts of the MCV and associated environmental conditions from the 10-member Storm-Scale Ensemble Forecast (SSEF) system produced for the 2007 NOAA Hazardous Weather Testbed Spring Experiment are compared to those from a similarly configured, but coarser, 30-member convection-parameterizing ensemble. It was found that forecasts of the MCV track and associated environmental conditions (e. g., midlevel winds, low-level wind shear, and instability) were much better in the convection-allowing ensemble. Errors in the MCV track from convection-parameterizing members likely resulted from westward displacement errors in the incipient MCS. Furthermore, poor depiction of MCV structure and maintenance in convection-parameterizing members, which was diagnosed through a vorticity budget analysis, likely led to the relatively poor forecasts of the associated environmental conditions. The results appear to be very encouraging for convection-allowing ensembles, especially when environmental conditions lead to a high degree of predictability for MCSs, which appeared to be the case for this particular event.
引用
收藏
页码:1052 / 1081
页数:30
相关论文
共 134 条
[1]  
[Anonymous], 1982, Aust. Meteor. Mag.
[2]  
Baldwin ME, 2002, WEATHER FORECAST, V17, P1063, DOI 10.1175/1520-0434(2002)017<1063:POTCSI>2.0.CO
[3]  
2
[4]  
Bartels DL, 1997, MON WEATHER REV, V125, P193, DOI 10.1175/1520-0493(1997)125<0193:SOAMVI>2.0.CO
[5]  
2
[6]  
BARTELS DL, 1991, MON WEATHER REV, V119, P104, DOI 10.1175/1520-0493(1991)119<0104:MCVGBM>2.0.CO
[7]  
2
[8]  
Benjamin SG, 2004, MON WEATHER REV, V132, P495, DOI 10.1175/1520-0493(2004)132<0495:AHACTR>2.0.CO
[9]  
2
[10]  
Benjamin SG, 2004, MON WEATHER REV, V132, P473, DOI 10.1175/1520-0493(2004)132<0473:MWPWTR>2.0.CO