6.2 Operational Predictability of Explicit High Shear, Low CAPE Convection

Thursday, 14 January 2016: 1:45 PM
Room 338/339 ( New Orleans Ernest N. Morial Convention Center)
Lindsay Blank, North Carolina State University, Raleigh, NC; and G. Lackmann

High Shear, Low CAPE (HSLC) environments are characterized by 0-6 km shear vector magnitude > 18 m/s, surface-based convective available potential energy (CAPE) < 500 J/kg, and most unstable parcel CAPE < 1000 J/kg. These environments pose a difficult challenge for National Weather Service (NWS) forecasters. HSLC environments occur during all seasons, primarily during the cool season, and predominantly during the overnight hours. This timing creates a particularly dangerous situation for the public at large. HSLC environments occur nationwide, but most often occur in the Southeast and lower Mississippi Valley. These environments can be accompanied by severe weather, including significant tornadoes, but determining when an HSLC environment will produce severe weather is difficult. Numerical weather prediction (NWP) and convection-allowing models (CAMs) have been successful at predicting rotating convection in high-CAPE environments. The aim of this study is to determine whether or not NWP at operational resolutions yields predictive skill with regards to the explicit prediction of HSLC rotating convection at operational resolutions. The Weather Research and Forecasting (WRF) model is run at varying resolutions for four different HSLC cases (two hit cases and two null cases). These model simulations are compared to observations to test their accuracy using a variety of metrics including composite radar reflectivity, hourly precipitation totals, and rotational tracks. The results of these comparisons are presented.
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