[Ed. – David’s post is taken from his daily journal notes during his week at the HWT.]

2010_0517

I’m in Norman, Oklahoma, for EWP2010 to forecast severe weather scenarios using new technologies and software. This should be both exciting and challenging and I’m looking forward to the experience.

Much of the day was spent with an overview of the various products we will be using and testing and there is much that is new and potentially very useful. By early evening we switched into forecast mode and loaded up real-time data of the ongoing convection and severe weather in southwest Texas and southeast New Mexico. Not surprisingly, there were a few software glitches but there always are with these type of programs and we just worked our way through it. Eventually we were able to view the multi-radar data fields and the new satellite tools. These included convective initiation products and overshooting convective cloud tops. Because these are new tools that we have not used before, it takes some time to learn how to use them and how they can be used to improve severe weather warnings.

2010_0518

We started with a debriefing of yesterdays events over the southern High Plains. Next we briefed on todays expected weather which should include supercells with tornadoes possible over the southern and central High Plains.

We received a brief overview of some of the new satellite products including the simulated satellite data generated from model output. It uses NSSL 4km WRF data to simulate all IR bands and produces results that are very similar to true radar data. It is, however, very compute intensive and requires many hours to generate. It’s unlikely that we will see this product on any operational workstation in the near future.

After the EFP weather briefing, we began forecasting operations for the day. Our group of four broke into 2 groups of two with our group forecasting for AMA and the other for PUB. Within a short time, we had convective initiation but were unable to use the satellite CI products — or any others — because of excess cirrus cloud obscuring the low cloud. We switched to MRMS products and began the forecast. These new products are a challenge to use at first — as with any new product — but have great potential value. It requires that we load and these tools alongside the more conventional tools as we prepare our warnings.

There are simply too many products to attempt to use and view all.  One needs to judiciously choose a few and work with these during the forecast and warning session. To select too many will result in information overload. I suspect that the products that I selected today and that worked for me today may not be the same on another event. For today, I found the MESH and ROTATIONAL products to be useful as well as the REFLECTIVITY -20C for warning on large hail and tornadoes.

2010_0519

The debriefing today included comparisons between the warnings we issued and those issued by the NWS offices. Our team was warning for AMA and the other team was warning for PUX. There were only a few supercells and these quickly became severe and then tornadic so that warning was fairly easy. I’m not sure that any conclusions can be drawn from this event since we were competing against forecasters familiar with the area and consequently our warnings were usually a few minutes behind theirs in issuance time.

Today poses a Moderate to High Risk across portions of the central Plains and both teams will be forecasting for the OUN warning area. We sectorized by storms as necessary. The strongest storms of the day were generally north of the I-40 corridor and the other team handled most of these. We did warn on one storm in that area but our warning was almost 30 minutes later than that issued by the WFO and I believe ours was more timely. MRMS parameters suggested that this storm was not severe and not tornadic when initially warned. It’s possible that their upgrade to a warning was predicated upon the evolution of an earlier storm that quickly became tornadic. All or most of the storms in this area eventually became tornadic and VORTEX2 was operating in this area which allowed us to receive timely reports of large hail and tornadoes.

We warned on a storm that began near Lawton then moved towards Chickasha and eventually moved across south Norman. It was very slow to evolve and we delayed warnings until MRMS and base state data convinced us that the storm had finally evolved into a severe storm. First warnings were SVR, then extended, then finally TOR, extended, then dropped back to SVR. No tornadoes were reported by experienced chasers and spotters but large hail was reported 3S of NWC. I think holding back on the warning was an improvemnt on FAR for individual counties and cities early in the life cycle of the storm.

2010_0520

With the front now stalled across Texas we focus on that section of the country using KFTW as a localization. Severe storms form on the front and we warn on them using the new radar products. Not too different from the previous days. But there is one interesting feature and that is an outflow boundary and fine line moving westward. The AzShear and RotationTracks products both show this feature well and it could serve as an initition point for convection later in the afternoon. By the time we break, however, it has not yet done so.

In the evening we switch to KHSV so that we can use the pseudo-GLM (global lightning mapper). These are tools that we have not yet used and it maps all lightning channels including CG, CC, and IC.  The most interesting thing we notice is that there is substantial lightning being detected in the trailing stratiform region. The echo line is oriented north-south and during the evening a few low reflectivity notches develop on the rearward side followed by very strong winds on the leading edge of convection. It appears that rear inflow jets (RIJ) are developing under the mesoscale anvil. Reminds me of some Pre-STORM events.

2010_0521

Today we discuss and debrief on all the weeks activities. There is general consensus that the radar products are good tools and become more useful with use. We’re not yet certain of the value of the satellite products since they aren’t telling us much more that we can see with other products but it may be that there will be events in which they outperform the radar. So, other groups may see some value that we didn’t get to experience.

David Blanchard (Lead Forecaster, NWS Flagstaff AZ – 2010 Week 6 Evaluator)