Extended Forecast and Chase Results from this Week

Welp, not a lot to look forward to right now if you’re a storm chaser. It’s hard to believe how slow this season has been. Minus one significant tornado on Tuesday this week, the plains has been dead. I made a critical error on Tuesday and missed that tornado. I think my forecasting was solid leading up to the event. My forecast maps with the greatest tornado potential really never changed in the 5 days leading up to the event and ended up being pretty accurate. Below was my forecast map and the actual storm reports. I’m a chaser and focus on zeroing in on exactly where the greatest tornado potential will be, since that’s what I’m after, so anytime I get the area right where that will happen (red box below), then I’m pretty happy with my forecast. I think that was the case here where the best tornadic storm tracked right down the middle of the area I highlighted.

My plan leading up to the event was to hug the I70 corridor. That notion was further reinforced with Rich Thompson at SPC pointing out the only subtle difference between this setup and the analogs of significant tornado events was slightly better moisture quality. Anytime you are forecasting and there is a weakness with the setup/paramaters, a big part of my strategy is identifying the target that mitigates that weakness. In this case, hugging up close to the triple point where moisture pooling could increase dewpoints a few degrees was a priority for me. The models hinted at a cluster of storms along I70 in the last few runs before Tuesday’s event, so I was prepared for that (vs. a more discrete cell) and knew to stay with the lead supercell or more dominant storm on the southern flank. I largely executed on that strategy and stayed with a supercell from Rush Center all the way over to Wilson. The storm was tornado warned off and on and had a few decent wall clouds, but it never really got close to actually producing. It had a very wet RFD and the updraft base was a little skimpy, which led me to believe we just needed low level shear to ramp up, which I knew would happen as the evening progressed. I did several phones and streamed video of the storm back to KWCH, so did alright on coverage as the storm approached I70 at Wilson. There is a major void of roads off the SW side of Wilson and we knew we’d have to drop south a bit to swing around that void and tie back in with the storm off the east side of Wilson. This is where the error occurred. The storm had gotten high based and was getting ready to go through a merger on top of being embedded in a cluster of supercells. As we dropped off the storm temporarily to swing around it’s south side and get east of Wilson, we had a discussion about the storm to our south and whether or not it would have better tornado potential. That storm south of us was all alone, it had gone tornado warned way faster than the storms coming off the triple point area, mesoscale analysis maxed out sig tornado parameters ahead of it, etc. Virtually everything you would consider in making a decision as to which storm would pose a greater tornado threat pointed towards taking the south discrete storm. The one thing that didn’t point towards that storm was my forecasting target/strategy leading into the chase. We had a discussion and bailed south for the discrete storm rather than swinging back up to the east side of Wilson at that point. As soon as we got about half way to the storm it started to struggle with CINH or drier air, not sure which. At the same time the storm along I70 we left became dominant after it went through the merger and planted a wedge. That one hurt. I still think we made the logical decision, but the lesson here is to stick to your forecast and strategy leading into the day and don’t get sidetracked with short term trends as the day unfolds.

Missing that wedge would be a lot easier to swallow if we had an active stretch coming up, but unfortunately that does not appear to be the case. It’s impossible to get into details right now because the models have been jumping around a lot, but the general trend has been for the polar front jet to stay north and then be fairly weak with any waves that do cross the Rockies. There is a weak disturbance in a NW flow aloft pattern across the plains that may trigger some low end severe storms next Tuesday and Wednesday. Nothing major there though and it’s unlikely we’ll see much out of it. Then there is some hint that a weak trough will dig south about 7 days from now over the plains and possibly break off from the polar front jet becoming a closed low over the plains. Closed lows are not generally good tornado producers due to vertical stacking, so again probably no dice here. The GFS then has this closed low parking over the plains, somewhat reminiscent of a blocking ridge as the polar front jet arcs up and over the plains completely. As the low wraps back in to the polar front jet around May 20th, the upper air pattern begins to look a little more like you’d expect in May. If there is a single stretch of spring that always seems to produce in the plains it is May 20-30. I hardly ever get skunked during that 10 day stretch. I don’t trust this far out and we could very easily be chasing next weekend if the GFS doesn’t have a good handle on the upper air pattern, but if that doesn’t happen then my money says we’ll get back into action around May 20th or shortly there after. The only silver lining with the GFS is that with high pressure anchored in off the SE US for the next week or so and favorable trajectories up through the Caribbean and across the gulf over the duration of the forecast period, the Gulf should be primed and ready to go whenever the jet stream does get active again in the plains. Besides that, there isn’t a whole lot to be happy about lol. I did look at the CFS and ECMWF, but there’s no reason to make a long post detailing each model. We are in hurry up and wait mode. That’s the bottom line.

Alright, I’ll update again Sunday with an extended forecast. I’m checking model data daily so as soon as there is something to talk about I’ll be on it like a duck on a June bug so check back for updates.

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