EWP Blog

Luckily, we were able see real-time data with the LMA, CASA, and PAR systems, along with the WDSS-II multi-radar algorithms. When compared to the archived cases, real-time operations provided a much better picture of the challenges operational forecasters will have in base data interpretation, primarily due to the more realistic warning environment. Below are some of the main points that I would like to make about each system:

LMA:  With its quick updates, the 1km data aided in locating areas of updraft intensification and deviant motion trends. The ability to see the trend data was also a good indicator of storm strength/trend, especially in radar-sparse areas.  Future research will hopefully lead to additional tools for storm/warning forecasting and warnings.

CASA:  Although rapid updates from multiple radars can be overwhelming at times, the increased temporal and spatial resolution are well worth it.  To alleviate the rapid-fire of new radar scans from 4 separate radars, the multi-radar composite was utilized with success.  Especially in areas with sparse/distant radar coverage, this system should easily increase probabilities of detection and lead-times of severe weather events.  However, due to the detection of features not previously seen on the 88D, an increase in false alarm rate is also expected.  I also found that the sector scanning strategies took away from base data interpretation. Perhaps being able to manually control what sector is scanned would help in these situations.

PAR:  The rapid scans, along with higher resolutions above the traditional “spit-cuts”, were outstanding.  This helped increase the confidence of meso-cyclone and core strengths.  The ADAPTS strategy appeared to work quite well without compromising the base data moments.  Hopefully in the not-so-distant future, additional panels will be added to alleviate the beam broadening on the edges of our current panel, and allow a greater radar coverage area.

Multi-radar/Multi-sensor algorithms:  In my experience, the use of MESH and reflectivities at 0C and -20C increase warning confidence tremendously.  Other diagnostic products, such as MESH Swath, Rotation Tracks, etc… are also great tools to help with warning confidence and warning polygon construction.  Especially in areas where radar coverage is sparse/distant with respect to your targets, these algorithms are needed.  After using the multi-radar data in this workshop, and also in real-time operations at my office, I feel the products greatly enhance warning and non-warning decisions.

Kevin Brown (NWS Norman OK – 2009 Week 3 Evaluator)

The EWP was a great experience and I couldn’t really ask for much more. As a meteorologist from outside of the United States I was somewhat uncertain what to expect but what I found impressed me. Technologies that we used throughout the week were useful and the exchange of ideas between researchers and meteorologists is something we too should strive for. The highlight was Wednesday when several tornadic supercells developed over Oklahoma with one passing through the CASA domain. The 3Dvar set the stage for the supercell entering the CASA domain and had us thinking about a tornado potential before appearing on the casa radars.  When the cell moved into the CASA domain the rotation was apparent and we were able to send the warning quickly. The strong winds that followed the tornado were easy to identify in the CASA dataset and warnings could likely be narrowed down as confidence increases with the use of these x-band radars. The WSR-88D data also showed the TVS however it was after the CASA data showing an obvious potential to improve lead times. PAR data and scanning strategies didn’t have any apparent faults and with the improved resolution and frequency I feel features would be singled out earlier in an event and once again lead times would increase. The LMA data has potential but I felt that I would have to get more comfortable with it and develop a conceptual model of what to expect with larger supercells. Picking out a peak in the LMA data would prove to be difficult but the graphical tool on Google earth was useful and could increase confidence in warnings already issued. There may be potential to use the LMA data for storm splitting since it would show the two updrafts however cases showing a split were limited. Last of all were the multi-radar/sensor algorithms. Returning to my office without products such as the MEHS, Reflectivity at -20, MEHS and rotation tracks will prove to be a difficult experience.

Chris Wielki (Prairie and Arctic Storm Prediction Center, Edmonton, AB – 2009 Week 3 Evaluator)

Being part of the EWP was very worthwhile with the four separate test beds each offering unique opportunities. The phased array radar was extremely useful. The highlight of the week for the phased array was Wednesday night’s live event. I was working with Kevin Brown from the Norman office using the phased array to simulate test warnings for the storms. There are a number of very good features with the phased array, the fast temporal updates of 1 minute per volume scan and the higher resolution brings much better identification to features. The radar has the ability to quickly change where the range folding was occurring from one volume scan to the next which meant at most just one minute of bad data. We were able to view animated cross sections through WDSSII and actually watch the reflectivity cores rise and then come back down to the ground causing downburst signatures. The current phased array radar only has one panel so it had limited viewing as the number of storms increased. We only looked briefly at a tornadic storm in the CASA area but focused on the storm coming south from Oklahoma City to Norman which also had tornadic potential. This storm we could see the original outflow move out ahead of the storm then slow down as the storm caught up and reintensified. This is when the tornado developed which we could clearly track in the velocity and as it got close to the radar we even saw the debris swirl on the radar.

The CASA network with 4 low power Doppler radars each about 40 km apart was surprisingly useful. The fact that a 3DVAR wind analysis is done with the radar scans was very helpful. This analysis clearly showed gust fronts and rear flank downdrafts. It also picked up very well on the tornado. I had some hesitation about the system because it completes a volume scan in 1 minute and if there are numerous echoes in range it only does 1 to 2 elevation scans. I think in hail situations this could be a problem. The software is programmed to look for individual cells then scan up several cuts but we had too many cells in the area so that only 1 or 2 elevations were possible. There is also a numerical forecast of various fields which utilizes the radar data and goes out 1 hour in the future. This helps significantly improve situational awareness.

While the previous two systems are only available at Norman there are two other systems which we at Wakefield hope to access locally. The enhanced lightning detection network which includes in cloud and cloud to ground strokes has one domain centered over Washington DC. The VILMA or lightning density product helped with updraft detection and provides another reality check on storm structure. Being a coastal office and talking with the scientist about the fact that in cloud lightning almost always precedes any ground strokes, we could use this product to give some lead time at the beaches during the summer time about when lightning might occur. The lightning tied to individual cells producing trends helped in predicting intensification or weakening of cells. If the cell numbers could be color coded to indicate increasing or decreasing lightning trends this would help with quick identification of which cells might be increasing.

The final data set was multi sensor multi radar data. For now one domain is centered over Washington DC and covers all of our CWA. Some of the most useful products included real time MESH or hail forecast tracks and instantaneous size estimates. In the cases and two real time events it appeared a good estimator of hail size something always needed. These tracks could also be very useful in the proper shaping for a polygon warning. The circulation tracks are so dense it was hard to use it much but would like to look at it in more detail. There are numerous other products as well which will need to be examined but we ran out of time in Norman. We are working to set this up here for real-time use.

John Billet (NWS Wakefield VA – 2009 Week 3 Evaluator)