Denver, Colo. (WAVE) - Hello from Denver, Colorado! Tomorrow begins my 12th annual Great Plains Storm Chase, and I’m taking you along for the ride.
When I was 17 years old I was asked to become a part of the Storm Chasing Adventure Tours team, explaining weather phenomena and forecasts to tour guests during their weeks of storm chasing. This apprenticeship of sorts taught me an incredible amount about severe weather forecasting and mechanics, putting me way ahead of my peers when it came time to formally solidify my meteorological education in college.
Now, all these years later with a meteorology degree under my belt, I still come out to chase storms each year because of the educational enrichment it continues to provide me, which in turn results in better forecasts and severe weather coverage for those in WAVE Country. Additionally, we storm chasers act as eyes and ears for the National Weather Service and local emergency management in the areas that we chase in. Our storm reports provide crucial heads up to these organizations for warning decision assistance and emergency preparedness.
The context of this year’s chase is different than the past couple of years. 2017 and 2018 were below-normal severe weather and tornado years, full stop. This year has been a wild reversal of that trend, with tornado warnings issued in May numbering over 1,000 and tornado reports well over 600. This no doubt is an above normal severe weather season when it comes to tornadoes.
You’ve likely seen the destruction and the heart-breaking stories of those who’ve survived these tornadoes this year, and heard about those who didn’t. Parts of larger cities like Kansas City, St. Louis, and Dayton have all been affected by tornadoes this season, continuing to disprove the myth that cities are immune from tornadoes.
With this context in mind, it’s important that our chase group this week remain respectful, helpful, and safe as ever. When we stop at gas stations, check in at hotels, and pull over for a quick bite we want to make sure that people know that we’re guests in their community, not the other way around. Our goal is to not impede the efforts and safety of those who make a living in the Great Plains.
With the ever-increasing number of storm chasers, and worse, storm chaser traffic jams, it grows tougher each year to not become a part of the problem. Leading by example is key in this more chaotic environment, and being dedicated to safety and courtesy is a must. I’m proud to say that the group I chase with has always been a leader in this regard by knowing when to break off from a storm when it’s too dangerous, pulling off the road in safe places that don’t impede others, and by choosing storms that may attract less chaser traffic to them when possible.
Guests from all around the world come on these storm chasing tours to witness the awesome power of the atmosphere, take a few pictures, and learn about why the weather is so active in the central part of the United States. This is no joy ride, especially when you consider all the thousands of miles of driving and scarfed-down fast food you’re forced to endure.
The educational enrichment is my favorite part of this experience every year. I always learn something new or put new research to the operational test in the real world.
This year the latter is the case as I’ve been reading through research papers about best practices about how to interpret tornado debris detected on radar. The radar product that detects this debris is called correlation coefficient, and simply put it uses information returned by the Doppler radar beam to determine if an area contains objects of many different sizes and shapes, an extremely good proxy for debris like trees, dirt, dust, and sadly construction material.
The most recent research that was presented just earlier this year by Emmerson et al was able to draw the conclusion that you can roughly assign an EF-rating estimate to a tornado in progress based on how high in the atmosphere the tornado was lofting debris, as detected by radar. This is incredibly useful for us TV meteorologists and NWS meteorologists alike because we can now get a rough sense as to how strong a tornado is based on that tornado.
Frankly, the exact rating of a tornado isn’t the important part of this, but comparatively this is important because the tone and messaging of a warning or TV coverage will change drastically if you can tell a tornado may be a strong, violent EF-4 or EF-5 versus something closer to an EF-1 or EF-2.
All tornadoes are dangerous, regardless of the rating, but it’s certainly more powerful to have a sense of how bad a tornado is when you’re on the air because that has implications on how widespread the damage is and just how long the tornado will likely last.
I was able to put this research into action this past week by analyzing the Lawrence, KS tornado’s radar imagery in 3D (see below), seeing with the correlation coefficient product that the debris was lofted up to 20,000+ feet in the air, indicating an EF-3 or higher tornado at the time of the radar scan. The final survey results from the NWS found EF-4 tornado damage, which matches up with the research and what was seen on radar. While I hope not to see a damaging tornado this week (or ever), having this research in mind while analyzing a storm’s radar imagery will be something new to this year’s chase.
So, where are we going? With our starting point in Denver on Sunday morning we’re in good shape. It appears that the upslope flow regime where east or southeast winds create upslope lift in the atmosphere as they go up toward the Rocky Mountains to the west, will be the main driver of Sunday afternoon’s storm setup.
A weak trough of low pressure over the Southwest will provide southwesterly winds over the plains of Colorado, the Oklahoma Panhandle, and even parts of the Texas Panhandle. Moisture is plentiful given our elevation in these spots (you need less moisture for storm growth as your elevation increases), but given how weak the trough is over the Southwest the wind shear will be rather marginal.
Storm cells will fire up near the Rocky Mountains where this upslope flow is maximized, and drift east out over the western Plains. Our goal is to find the spot where these storms will have the best ingredients of wind shear and instability to stay individualized as supercells. It’s tough to say right now where exactly that location will be as surface observations, radar, and satellite data the morning of the event (tomorrow morning) will be critical.
The Storm Prediction Center’s outlook for Sunday has a Slight Risk of severe weather all up and down the High Plains east of the Front Range of the Rockies and even down to the South Plains of the Texas Panhandle. The SPC says...
That’s not bad considering how weak the wind flow is in the mid levels. The outlook for the rest of the week continues to be rather marginal, but things can change in a hurry this many days in advance. Honestly it’s a good thing that the severe weather pattern out here has calmed down compared to previous weeks. It’s been so dangerous for residents and storm chasers alike lately.
This upcoming week will be an easier one to chase with as storms won’t be moving as fast nor will they be as numerous. As I’ve said for years, severe weather outbreaks are usually bad days for storm chasing since the safety risk and the issues with storm speed and chaser traffic can outweigh the reward.
Be sure to keep up with my storm chase by following my social media accounts...
And of course at select times during our evening newscasts on WAVE 3 News this upcoming week I’ll be streaming video of our chase when possible. Daily (shorter than this post!) updates right here on the WAVE 3 Weather Blog (bookmark this link) will be available as well.