A Comparison of Several Analysis Schemes In Their Ability To Diagnose Boundaries

Abstract

There have been a number of recent additions and changes to analysis schemes available or potentially available to operational forecasters. The Local Analysis and Prediction System (LAPS) has been available on AWIPS at 10 km horizontal grid resolution since the late 1980s, but is now run at some National Weather Service (NWS) Weather Forecast Offices (WFOs) at a resolution of 5 km or even smaller. A new version of LAPS is being tested at NOAA/GSD at 1 km resolution. Another new scheme that is currently being run nationwide for aviation purposes, called STMAS (for Space and Time Multiscale Analysis System), is being run on a Colorado-area scale at GSD at 5 km horizontal resolution. Forecasters now have access to hourly output from the NCEP Real-Time Mesoscale Analysis (RTMA), run at 5 km horizontal grid resolution and available on AWIPS. The Rapid Update Cycle (RUC) Rapid Refresh model is now run hourly in an analysis and short-term forecast mode and available to forecasters at a 13 km horizontal grid resolution. Analyses from the RUC Rapid Refresh are now being used to run an experimental High-Resolution Rapid Refresh model (the HRRR) at a 3 km horizontal grid resolution out to 15 h. The analyses and forecasts are available in real-time on the RUC website, but many WFOs are also displaying selected grids on their AWIPS. There are variations among these schemes not only in resolution, but also in how they assimilate the various data sources. Forecasters often use an analysis scheme to help monitor derived quantities such as Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) to help determine convective potential. Analyses are also typically used to help better define boundaries, either stationary or moving boundaries such as larger-scale outflows. Derived surface fields of convergence and vorticity are often used to help better diagnose and quantify the strength of a boundary and determine its potential to influence the short-term weather (via convective initiation or forcing of a precipitation band, for example). In this study we will examine the various analysis schemes with a focus on how useful they are in diagnosing various types of boundaries. A subjective examination of a variety of both summer and winter cases in the Boulder WFO area will be used, focusing on whether the analysis scheme would be a useful forecast tool for monitoring and diagnosing boundaries and their potential to influence short-term weather.