Convective Downburst Potential Using GOES Sounder Derived Products Convective Downburst Potential Using GOES Sounder Derived Products Kenneth L. Pryor and Gary P. Ellrod Office of Research and Applications (NOAA/NESDIS) Camp Springs, MD Andrew A. Bailey Raytheon ITSS, Landover, MD Date Submitted: January 10, 2002 Abstract Retrieved profiles of temperature and moisture obtained from the Geostationary Operational Environmental Satellite (GOES) Sounders have been shown to be useful in assessing the potential for convective downbursts. Sounder-derived parameters used for this purpose include the Wind Index (WINDEX) for estimating the maximum wind gusts, a Dry Microburst Index (DMI) and maximum Theta-e Difference (TeD) for dry and wet microburst potential, respectively. These parameters are conditional on the development of convection, however, thus requiring analysis of other environmental factors as well. The experimental indices are plotted on regional GOES images (Visible, Infrared, or Water Vapor) and made available on the GOES Microburst Products web page( URL: http://orbit-net. nesdis.noaa.gov/arad/fpdt/mb.html). This paper briefly reviews each of the GOES microburst products, describes recent improvements, provides updated verification and a case study, and discusses future plans. Recent improvements include a change in the first guess numerical model, use of single field-of- view retrievals, a filter for removing high DMI values where convection is unlikely, animation of many sectorized products, and color-coding of TeD or WINDEX ranges for data plots. A case study on a dry microburst event that occurred in southern Idaho and produced wind gusts of over 50 kt is presented. Validation continues by comparing product output values to preliminary severe weather reports from the Storm Prediction Center, surface observations, and summaries from the Cape Canaveral, FL mesonet. Mean error, determined from the difference between mean GOES WINDEX and mean measured wind reports, was <3 kt for 92 daytime events during Summer 2001, but GOES WINDEX underestimated wind gusts for 38 out of 55 nighttime events. In addition, mean error for GOES WINDEX is about 2 kt less than mean error for WINDEX derived from the National Centers for Environmental Prediction (NCEP) Aviation (AVN) model first guess. A planned enhancement is to calculate WINDEX at night using data from the top of the boundary layer instead of the surface to reduce the negative bias. Also, the microburst products are scheduled to be implemented in the Advanced Weather Interactive Processing System (AWIPS) at National Weather Service Forecast Offices as part of Build 5.2. 1. Introduction The downburst is defined as a strong convective downdraft that induces an outburst of damaging winds http://www.orbit.nesdis.noaa.gov/smcd/opdb/kpryor/mburst/cdp/cdp.htm (1 of 11)08/11/2005 4:11:02 AM