Revised Virtual Institute for Satellite Integration Training (VISIT) Lesson

The Virtual Institute for Satellite Integration Training (VISIT) Lesson titled “Forecasting Convective Downburst Potential Using GOES Sounder Derived Products” has been revised by K. Pryor to include new case studies and new instructional material pertaining to the Graphyte Toolkit and the Geostationary Operational Environmental Satellite (GOES) channel 3 – channel 4 brightness temperature difference (BTD) product. The objective of the lesson is to provide better understanding of techniques for predicting the risk of convective downbursts utilizing Geostationary Operational Environmental Satellite (GOES) sounder derived data. The guide for the lesson as well as the revised version of the lesson are available on the VISIT web site.

Figure 1. Page 29 from VISIT lesson “Forecasting Convective Downburst Potential Using GOES Sounder Derived Products” displaying the new Geostationary Operational Environmental Satellite (GOES) imager channel 3 – channel 4 brightness temperature difference (BTD) microburst product.

Figure 1 shows new instructional material from the VISIT lesson “Forecasting Convective Downburst Potential Using GOES Sounder Derived Products”. This page compares a Geostationary Operational Environmental Satellite (GOES) imager channel 3 – channel 4 brightness temperature difference (BTD) product to a pre-convective GOES sounding profile during the afternoon of 5 August 2010. Note that the dry-air notch in the product image on the left is pointing southeastward toward a convective storm moving through the Washington, DC area. The presence of mid-tropospheric dry air was established by the GOES sounding profile over Washington, DC about two hours prior to strong downburst occurrence. The channeling of dry air into the rear of the convective storm most likely played a significant role in generating downdraft energy. Downburst wind gusts of 42 knots were recorded by the Washington Tide Station and the Upper Potomac River (white cross) buoy during the afternoon of 5 August 2010.

2010 Microburst Product Assessment Results

The 2010 assessment of the GOES microburst products has been featured in a research paper titled “Recent developments in microburst nowcasting using GOES” published in the electronic journal “ArXiv.org” and the preprints of the 17th Conference on Satellite Meteorology and Oceanography. The paper provides an updated assessment of the Geostationary Operational Environmental Satellite (GOES) Microburst Windspeed Potential Index (MWPI) and new GOES brightness temperature difference (BTD) algorithm, presents case studies demonstrating effective operational use of the microburst products, and presents validation results for the 2010 convective season over the United States Great Plains and Atlantic Coast regions. Favorable results presented in the paper include a correlation between MWPI values and measured wind gusts of 0.62 that was found to be statistically significant near the 100% confidence level. The very high confidence level indicates a high likelihood that the correlation represents a physical relationship between MWPI values and downburst magnitude and is not an artifact of the sampling process.

Figure 1. Poster titled “Recent developments in microburst nowcasting using GOES” presented by K. Pryor at the 17th Conference on Satellite Meteorology and Oceanography in Annapolis, Maryland on 30 September 2010.

Figure 1 displays the poster presented by K. Pryor at the 17th Conference on Satellite Meteorology and Oceanography. The poster presents a new visualization of the MWPI product as generated by the Graphyte Toolkit, two case studies of significant downburst events, and validation results. Favorable validation results include a statistically significant correlation between index values and measured downburst wind gust speeds with a confidence level near 100%. The poster also introduces a new GOES-imager derived brightness temperature difference (BTD) product that highlights the physical process of dry air entrainment into deep, moist convective storms and its role in the generation of downbursts.