2009 Preliminary Microburst Product Validation Results

Preliminary validation results for August 2009 have been completed for the Geostationary Operational Environmental Satellite (GOES) Microburst Windspeed Potential Index (MWPI) and imager microburst products. GOES sounder-derived MWPI values have been compared to mesonet observations of downburst winds over Oklahoma and Texas for 156 events between June 2007 and August 2009. The correlation between MWPI values and measured wind gusts was determined to be .64 and was found to be statistically significant above the 99% confidence level, indicating that the correlation did represent a physical relationship between MWPI values and downburst magnitude and was not an artifact of the sampling process. Comparison of GOES-11 imager microburst risk values (output brightness temperature difference (BTD) in degrees K) to measured downburst wind gusts for 49 events in Oklahoma between June and August 2009, yielded a correlation of .42. This correlation was higher than the correlation computed between MWPI values and downburst wind gusts (.32) for the same time period. The correlation between output BTD and measured wind gusts was determined to be statistically significant at the 85% confidence level. The results of this t-test also indicated a high likelihood (85%) that the correlation represented a physical relationship between output BTD values and downburst magnitude.

The images above are scatterplots of Geostationary Operational Environmental Satellite (GOES) Microburst Windspeed Potential Index (MWPI) values (top) and GOES-11 imager output BTD values (K) (bottom) versus observed downburst wind gust speed as recorded by mesonet stations in Oklahoma and Texas between June 2007 and August 2009 (top) and mesonet stations in Oklahoma between June and August 2009 (bottom). The MWPI scatterplot identifies two clusters of values: MWPI values less than 50 that correspond to observed wind gusts of 35 to 50 knots, and MWPI values greater than 50 that correspond to observed wind gusts of greater than 50 knots. Similarly, the GOES-11 imager microburst risk scatterplot identifies two clusters. The dominant cluster contains output BTDs less than 50K that correspond to observed wind gusts between 35 and 50 knots. The scatterplots illustrate that both microburst products demonstrate effectiveness in distinguishing between severe and non-severe convective wind gust potential.