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Surprise storm?

Over the last few days, thunderstorms blossomed over two very different parts of the country resulting in tornadoes and subsequent damage. While there were injuries, fortunately, there were no fatalities. You may have seen the dramatic images from Tulsa, Oklahoma from storms as several tornadoes struck, including an EF2 (estimated winds 130 mph) just after 1 am local time (images courtesy @BostonHeath);

That was followed two days later by an EF1 tornado (estimated winds 110) in Salisbury, Maryland (images courtesy @mcmanus_tommy):

 

In the aftermath, some people in the affected areas expressed concern that there was “no warning”. Is that true?

In the era of 24/7 monitoring of weather and advances in radar detection technology, there really are very few surprises. Often, there is great awareness among those in the weather community that there is an imminent threat, but the general public sees the outcome as “sudden” and “coming out of nowhere”. So where is the disconnect? In this digital age, the real challenge is communication. These two are both examples of a good job from the weather forecasting point of view, which wasn’t fully relayed to the general public. Let’s take each of these episodes and break them down:

First in Tulsa, Saturday August 5 going into early Sunday morning August 6 –

A severe thunderstorm watch had been issued at 9 pm on that Saturday night. The watch means there was a potential for dangerous storms to develop with damaging wind gusts and hail as the main threat which was expected until 2 am Sunday. Here’s the area it covered in Oklahoma shaded in blue:

It was a Saturday night, so how many people knew about this? Perhaps some of the local TV stations announced it some way, but many may not have been aware. Additionally, severe thunderstorm watches are fairly common in the summertime and often lead to noisy, but not particularly destructive storms forming in the heat of the day. In “Tornado Alley”, the “T”-word gets people’s attention; few change plans otherwise.

At roughly 1 am, a line of storms moved into northeast Oklahoma, targeting Tulsa and the surrounding areas. Unlike the single “super-cell” storms that spawn tornadoes common in the plains, these thunderstorms formed a kind of line. Often, along the line, fast-developing vortexes of wind can form. This was the case early Sunday morning. To cover the broad effects of a line of storms like this, the National Weather Service office issued a Severe Thunderstorm Warning at 1:08 am. The yellow outline below represents the warned area. The bright red, yellow and orange colors are the strongest parts of the storm and the white is the area where the tornado formed:

That was followed by a tornado warning (outlined in red) at 1:25 am, but by that time, the damage in Tulsa had already occurred:

Those WeatherCall customers within the yellow box received their call letting them know that the thunderstorm they were experiencing wasn’t just an “ordinary” thunderstorm. This effectively gave them a 15-minute lead time on the tornado that eventually struck, which would have given them ample time to take safety action. Often, but not always, a storm like this can escalate and the warning will be upgraded to a tornado warning. However, in most cases, the general public rarely pays attention to a severe thunderstorm warning and few even get these kind of notifications sent to their phones. The main way people know about a severe thunderstorm warning is by the scrolling words that interrupt their favorite TV program. Again, in this case, it was late Saturday night and few were likely watching at this hour.

So the bottom line in the Tulsa case – yes, there wasn’t a tornado warning at the time the storm produced the tornado, but there was “a” warning. The fact that the line of storms produced a tornado might have been a surprise, but the fact that there were severe thunderstorms moving through was not.

Now, let’s look at the Salisbury case –

On Monday, August 7, parts of Delaware, Maryland and Virginia were under a Slight Risk for severe weather indicated by the yellow shading:

This classification of “slight risk” means that storms may develop that could produce severe thunderstorms where the main threat is gusty wind, hail and isolated tornadoes. I wonder how many people were even aware of this? Unless they very diligently watched local news reports or visited the National Weather Service’s Storm Prediction page, they likely did not know weather of this scope was a possibility.

As storms developed from low pressure dragging a cold front through the region, heavy rainfall and flash flooding began to develop in Maryland and Delaware. At 1:37 pm, the National Weather Service issued a Severe Thunderstorm Warning which included Salisbury. The warning, again, is highlighted in the yellow line and brighter red colors represent the storm that produced the tornado and wind damage:

 

 

How many received the severe thunderstorm warning notice and if so, knew that they should take action? In this case, a tornado warning was never issued for this storm, but again, “a” warning was in effect.

Both of these cases were isolated within the scope of the overall storms that formed, but the fact that everyone could see the damage via social media and the perception of a “lack of warning” is garnering some attention.

The collective weather Enterprise comprised of government agencies and the private sector need to do a better job of sending effective messages to the public and continuing to educate them as to what to do. These cases also underscore why it is critical to have multiple ways to get weather warnings and to be aware of changing conditions. Summer tornadoes aren’t common, but severe weather can and does happen year-round.

Are there instances where storm threats develop suddenly? Yes, but they are becoming more and more rare. As technology improves, so will the ability to refine warnings, track evolving threats and communicate more completely so there will likely be fewer “surprises”.

Regardless of how you receive warnings, consider adding WeatherCall to your process and choose to receive notifications for both severe thunderstorm and tornado warnings. Sometimes, within the text of the severe thunderstorm warning, there may be an indication that a storm is capable of producing a tornado so you can take appropriate action.

 

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