While these storms didn't look all too impressive on reflectivity images - they were moving fast, and dumping a good deal of rainfall. In fact, 2.14 inches of rain was recorded at San Antonio International Airport, and several wind gusts through the area were reported to be over 60 miles per hour - and a few reports of hail were also documented.
Originally Posted on DanielSchreiber.org
Yes, a lot of news media does tend to hype up the forecast. In fact, straight from a TV meteorologist himself: “we have to lead them [viewers] on…I tease them that way they stick around for 15 or 20 minutes, that way they watch the newscast, see the advertisements, and we make our money”. You can watch that entire shameful video here.
So yes, the media won’t necessarily be the most honest when it comes down to storm coverage. Perhaps that’s why many people seem to blatantly ignore important weather warnings.
One of the toughest parts of my job as a meteorologist is explaining that just because some sort of weather – especially severe weather – is in the forecast, doesn’t always mean that an exact location will be impacted – but rather the general area.
According to the first frame, if it rains on Larry’s Used Car Lot on Saturday as prescribed, Larry will probably gain confidence in the TV weatherman. But, let’s say that it doesn’t rain at Larry’s Used Car Lot, but rather 10 miles away in every direction (top right frame), then Larry will probably be upset if he cancelled his party, because it didn’t rain at his car lot. On the other hand – the meteorologist will probably say his forecast was pretty accurate, since there was rain all over the surrounding area. In this case, it’s an easy conclusion to say that meteorologists shoot for accuracy – and as a result are generally accurate – while the end user, like Larry, also expect precision. That makes a weatherman’s job very difficult.
Imagine if the forecast above showed “Partly Cloudy”, with a 70% appended to it. What would the reaction be? Likely much different than the reaction to the graphic above, even though they literally mean the same thing. Why is this?
Well, after reading what some psychologists had to say about graphics, it looks like we may have a clue. Written information is processed by the analytical side of the brain. Every human being can make a conscious choice whether or not to process that information. But, graphics are processed immediately and involuntarily by the right side of the brain – and provide an initial impression regardless of the written content.
I believe this is why many people don’t trust meteorologists – and why many people don’t heed storm warnings. In the case of the Thunderstorm Chance graphic above – if no thunderstorms are observed by the end user – which is a 70% chance – then the trust for the National Weather Service by that end user many suffer. But, if the National Weather Service remains silent about the 30% chance of thunderstorms, and thunderstorms do in fact occur, then the trust also suffers. Kind of a debacle.
I deal with this all the time…
In the above graphic from May 25th, 2015, the Storm Prediction Center highlighted areas across the United States that would see thunderstorms, and in some cases, severe thunderstorms and tornadoes. These areas are in darker green, yellow, orange, and red, each with a corresponding percentage – or chance – of occurring.
For example, a “Marginal” threat means that there is less than a 15% chance of a severe thunderstorm occurring within 25 miles of a point within the highlighted area. In other words, “isolated”. Likewise, “Slight” generally encompasses percentage of severe storms occurring between 15% and 30%, within a 25 mile radius. And so on.
In the above May 25th, 2015 forecast, we can see that most of the severe weather reports occurred in the areas highlighted in orange and red – since these areas highlighted the highest potential.
However, there is also a noted large swath of area – like much of Deep South Texas and Louisiana and a good bit of the Central Plains – that didn’t receive a reported severe thunderstorm, despite being highlighted with potential. Even parts of the orange (enhanced potential) and red (moderate potential) didn’t observe a severe storm, but it doesn’t necessarily mean that the forecast was inaccurate.
The problem is, combined with media hype and a game of social-media gossip, 15% of severe storm potential (within 25 miles, mind you) – while literally meaning 85% chance of no severe storm – can be misinterpreted to “a severe storm is expected to occur”. After time and time again of these misunderstood “false alarms”, folks loose faith, and may even disregard an imminent severe weather warning – like taking shelter for a tornado headed toward them.
I’m not suggesting that anyone should disregard low-end chances of severe weather! All I’m saying is: Take the forecast at face value, read the description, and be aware of the potential.
-Meteorologist Dan Schreiber
Dan Schreiber is an operational meteorologist, with experience