The last week of the EWP2010 was a successful one with ample opportunities to test and evaluate the latest technologies soon to become available to operational meteorologists. As a SCEP at the NWS Tallahassee, FL, I had little previous warning experience. Initially, the program was a bit overwhelming, with so many new products to evaluate and only one short week to do so, however, by the later part of the week, certain products became favored over others and the process of developing situational awareness became more natural and comfortable. Our week was the last of the program and was geared toward the GOES-R and MRMS products. My comments on each of these can be found below. We had a very busy couple of days on June 16th and 17th with a long lived tornadic supercell over South Dakota and a widespread tornado outbreak on the 17th. These two days were challenging and the products in development at the HWT were very useful in the warning decision process. I’d like to thank all who were involved in putting the program together as well as those who stayed around for support. It was a lot of fun and I hope I can make it out again soon.
MRMS Products
The Multi-Radar Multi-Sensor algorithms were an excellent tool during the warning process. In particular, those which emphasized reflectivity at the 0°C, -10°C, and -20°C isotherms were instrumental in assessing hail potential. These combined with products such as the 50 dBZ echo top height above -20°C and layer average reflectivity at the various isotherms highlighted major storms versus those that posed a lesser severe threat. In terms of MESH versus MESHb, storm reports showed that MESH outperformed MESHb when considering more classic supercellular/tornadic storms while MESHb worked well in multicell/linear MCS type events where updraft strength was not as robust. These tools were also useful in terms of delimiting severe warned areas. Looking at reflectivity well above the freezing level allowed forecasters to notice non-descended cores that may produce severe weather downstream. This improved overall polygon size and orientation considering future threats.
In terms of analyzing tornado potential, rotation tracks and the low and mid level shear products were good to reference when orienting polygons. With these tools, storm rotation trends could be derived and tornado warnings could more accurately reflect the individual threat from the tornado. These products complimented base reflectivity and velocity data well and provided extra guidance on the location and motion of potential tornadic circulations.
Overall, the MRMS products were most useful during the warning phase of the experiment. They provided a good quick look when analyzing traditional radar data and a confidence booster when issuing warnings for severe hail and tornadoes. Products geared toward reflectivity thresholds provided an overview of which cells tended to be more severe and how they were growing/decaying over time. This prevented possible oversight of minor severe storms while focusing on those that were producing the most severe weather at the time. I hope to see these products move into the operational realm so more forecasters have an opportunity to test them in real severe weather scenarios.
GOES-R Products
The GOES-R tools were mainly geared toward convective activity. A convective initiation algorithm was developed to discern areas of likely impending thunderstorm development. This product would be very useful, especially for aviation interests when making short-term changes to TAFs to reflect thunderstorm threats. It would also be a good reference for putting out watches/mesoscale discussions when forecasting short-term probability of severe weather given a volatile thunderstorm environment. Unfortunately, we were unable to effectively evaluate this product as the shifts took place in the afternoon after most convection had already initiated. Verification was carried out the day after to see how severe reports lined up with the CI detections. Overall, I feel that visible satellite would likely clue me in on convective initiation, but the tool performed well in retrospect.
In addition to these, overshooting top (OT)/cloud top cooling and enhanced-v signature products were developed to indicate the likelihood of severe weather for particular storm cells. OT detections were widespread with very few enhanced-v signatures detected. Enhanced-v detections were always associated with severe weather, mainly in supercell thunderstorms. Some overshooting tops on visible satellite were missed, but overall it performed fairly well. The real question is how useful would such a product be in a warning situation. I would not feel comfortable warning solely on an OT or enhanced-v detection without some base radar data or perhaps MRMS imagery to back it up. These products would have been better before the event began and in a regional sense to get a feel for where the strongest convection was occurring, or where the greatest potential for severe weather would begin. One glaring limitation of the GOES-R products is that they only work under clear skies with no cirrus present. Overall, I found these products to be more interesting than useful in terms of issuing warnings; however I was not able to evaluate them thoroughly due to time limitations.
Marcus Austin (Student Career Employment Program, NWS Tallahassee FL – 2010 Week 9 Evaluator)