March 2019 President’s Message

Annual Meeting Abstract Idea?

Paul Schlatter, NWA President

You still have time…the deadline to submit an abstract for the NWA Annual Meeting in Huntsville, Alabama, is March 7. Recall from the February newsletter that the Annual Meeting Steering Committee, which leads the process to accept talks and posters and assign them to sessions, is looking for abstracts that are interactive, jointly presented, and tie into this year's theme of “Pay it Forward.” You also have the option to recommend a session or special event. Whatever you do, make plans to attend and finish that abstract you keep putting off for tomorrow. There are only a few tomorrows left!

I want to make another plug for the Mentor/Mentee Special Session at the upcoming Annual Meeting. If you ever wanted to pay it forward for someone who was instrumental in your career, this is a fantastic way to do it. We are looking for mentor/mentee pairs to be a part of a panel discussion moderated by yours truly. My goal is to get a discussion going that highlights how you met your mentor, what makes the relationship special, and how it’s mutually beneficial. I truly believe everyone in attendance will benefit from hearing about mentorship from both sides of the coin. Submitting an application is easy: just answer a few simple questions about you and your mentor. The best part is that there is no fee for it, so what do you have to lose? To submit an application, go to the call for abstracts page on the NWA Annual Meeting page and click on the button for “Mentor and Mentee Session Form.”

For the remainder of this month’s message, I wanted to share a story from the forecast desk. I was working an evening shift that started at 1 p.m. on Saturday, Feb. 16. I mention the start time because I used the first and probably most important tool in any forecaster’s toolbox: a visual inspection of the atmosphere! Before looking outside to the west, I had briefed myself on the weather message of the day via the morning Area Forecast Discussion issued by my office (NWS Boulder). Extremely cold air aloft was being advected over the foothills west of Denver and forecast to be over the plains during the afternoon (forecast to be -30 C at 500 mb, and -17 C at 700 mb). At the surface, temperatures had warmed to 40 F by midday with the strong mid-February sun. While numerical models indicated the potential for convective snow showers, they were unable to predict the intensity, timing, and evolution of the activity we saw that day. This is not unusual for model forecasts of this type. In events like this, we take what we can get from numerical weather prediction, but most of the time using observational data is the only way to understand what the atmosphere is about to do.

On my drive into work, I saw convective towers just west of Denver over the mountains. It reminded me of a summer day when convective storms form over the mountains midday and move east over the plains by early afternoon. Only, this was February, and the convective showers were dropping heavy snow in brief bursts. Our conceptual model of convective snow showers forming over the mountains on the leading edge of the cold air aloft and then moving east over Denver was occurring in real-time when I arrived at work. It would be feast or famine—anyone directly under one of those showers would experience 1/4-mile visibility and a quick inch of snow in roughly 20 minutes. It would be over about as quickly as it started. While in the office, we used radar and satellite data to monitor the progression of the convective snow showers. Operational meteorologists are in the business of predicting impacts, so we also utilized webcams from across Denver to see what was going on in the worst of it. The Colorado Department of Transportation has webcams on every interstate in the metropolitan area spaced approximately every mile. We also used Twitter, because citizens across the front range of Colorado love tagging our office (or via broadcast meteorologists retweeting the photos as we follow them) with weather-related photos, videos, and other useful information. As the showers moved across Denver, we found webcams showing the heavy snow and low visibility. We were posting across social media platforms on what to expect: brief near white-out conditions, wet to perhaps slushy conditions, and we urged drivers to slow down. We were sending out radar updates every 30 minutes or so as the showers organized into a line, reiterating that drivers should slow down when they encounter the snow squall.

Some of you may wonder if we issued a snow squall warning. Wait, what’s a snow squall warning? The NWS is experimenting with a new short-fuse warning product called a snow squall warning that is similar to a severe thunderstorm warning but issued when rapidly deteriorating conditions are expected from convective snow showers. The warning is for heavy, short-duration snow that reduces visibility to 1/4 mile or less, contains gusty winds, and/or results in treacherous travel on roads that are expected to quickly ice up either from the intense rate or the cold road temperatures. NWS Boulder is not one of the offices experimenting with these warnings; otherwise we would have issued one given the intense snow and potential for icy roads. By 4 p.m., the snow band continued to the east and approached Peña Blvd, the freeway that connects Denver to Denver International Airport. The band slowed down with intense 40-45 dBZ echoes right over the freeway. Unfortunately, there are no webcams along the route so we weren’t sure how bad it was when Twitter came through for us with a photo of the conditions.

The roads were clearly slushy, snow packed, and likely slick with severe restricted visibility. Winds were not contributing to the lower visibility (10 mph at the time), confirming the sheer amount of snow falling all at once. In about 45 minutes, 2 to 3 inches fell over that stretch of freeway. The low visibility and slick conditions led to a 49 car pileup of people trying to get to the airport. While 17 people were injured, thankfully none of the injuries were serious. It was a sobering moment for our office because up until that point there were no accidents as the heavy band moved across the metropolitan area until the band slowed down over the freeway. I tell this story to illustrate that this event was tailor-made for a snow squall warning. Would a snow squall warning have helped prevent the 49 car pileup? That’s up for discussion, but I think it would be unlikely given the intensity of the snow and desire the drivers had to get to the airport at that time on Saturday afternoon. It only takes one car going too fast for the conditions to cause an accident like that. In the near future (hopefully by next snow season) these new products will be available across the country and, as an enterprise, we’ll need to band together to explain to the public what the warnings mean and what to do when they are issued. Maybe someone from one of the offices that issue these warnings will team up with a broadcast meteorologist or emergency manager to share their experiences at the Annual Meeting? "You are welcome" for that abstract idea!

Read the full March Newsletter. 

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