First Alert Weather In-Depth: Tracking your summer

“What does it take for severe weather to form?”

By Alex Bielfeld

Severe weather can occur all year round here in Western New York, but our chances for strong storms increase during the Summer months. Just like every other weather phenomenon, we need the right ingredients.

A major ingredient for severe weather to form is moisture. Just like how your car runs on gas, thunderstorms need moisture in the low levels of the atmosphere. The way meteorologists measure moisture in the atmosphere is by the dew point. Typically, we need dew points 55 degrees or greater as this gives us the best chance to destabilize the atmosphere. The higher the dew point, the greater the chance for thunderstorms.

Just because there is moisture in place doesn’t mean that thunderstorms will pop. We need clouds to grow. The spicy ingredient that lets clouds grow is instability. Instability occurs when cold and dry air overrides the warm and moist air at the surface. The temperature gradient, or difference, forces the warm moist air to rise then cool and condense into clouds. An analogy that can help you imagine this is boiling a pot of water. When you put the pot of water on the stove at first, nothing happens. However, when you turn the stovetop on, it begins to heat the surface of the pot. Then as time progresses, the water boils and the steam that comes out of the pot is the water vapor rising, cooling, and condensing.

So we are halfway through our weather recipe, but we still need those clouds to explode into thunderstorms. Just like baking soda in a cake, or yeast in bread, things need to rise. Although we have moisture and instability, we need this energy to rise and lift provides just that. Lift in the atmosphere can come from the jet stream, low-pressure systems, and frontal boundaries such as warm and cold fronts.

Our severe weather soufflé is coming together nicely, but there is one more kick we need in order for the strongest of the storms to roll through. For the strongest storms to roll through, a maintain strength, we need it to spin. Wind shear will provide the rotation needed for strong storms, and for storms to potentially become super-cellular. There are two types of wind shear. Vertical speed shear, and vertical directional shear. Vertical speed shear is when winds generally maintain the same wind direction as you move up in the atmosphere, but increase with speed as you move up. Vertical directional shear is when the wind direction changes as you move up in the atmosphere. Both of these play a role in tilting the updrafts of a thunderstorm, and this tilt is important because it allows the updrafts and the downdrafts of a storm to maintain and gather strength. Directional wind shear is important too as this is what rotates the updrafts and allows them to become super-cellular at times. These storms can then move through with strong gusty winds, damaging hail, and on occasion locally a tornado.

We will continue to track these ingredients throughout the Summer months and deliver that information to you. Tune into News10NBC as we alert you days in advance of any impending severe weather with our First Alert threat Tracker and download the free First Alert Weather App for the latest weather information and real-time radar data at your fingertips. Oh, and one more thing, when thunder roars go indoors! Stay safe and have fun this summer!

Extreme weather

By Glenn Johnson

You know that on any given day we are talking about extreme weather across the country. It could be heavy snow, some flash flooding, tropical storms or maybe high winds.

But how many people are directly affected by extreme weather? The folks at Gallup Polling decided to take a close look at this and what they found was revealing. Gallup did a survey of a good portion of the U.S. population. That poll showed that one out of three people has reported being affected by some amount of extreme weather in the last two years. To get that information they surveyed more than 1,000 people across all 50 states. That works out to be the equivalent of 60 million Americans having had some kind of direct impact when it comes to severe weather.

We can break this down regionally. Let’s start with the Northeast where 24% have experienced some kind of extreme weather. And the elements that had a direct impact were floods and hurricanes.

Now to the Midwest and you see that 27% have experienced some kind of severe weather. The extreme weather that they experienced was heavy snow, freezing rain and ice, floods, and of course tornadoes.

The numbers are starting to increase when you reach the far West. Some 35% of the population has experienced severe or extreme weather. And it has been wildfires, extreme heat and drought making the impact. We know this has been a long-term problem for that part of the country.

Then we head to the Deep South. Upwards of 40% of the Americans there have experienced some kind of extreme weather in the last two years. The elements that they have been dealing with is extreme cold. That may seem kind of counterintuitive, but remember back in 2020 in Texas they had a severe cold snap and that effectively shut down the power grid for a long period of time. And the other element is hurricanes. The National Hurricane Center has stated that there were 19 tropical storms that made landfall in this portion of the country over the two-year period.

So what about the people in Rochester? We have certainly had our share of flooding rain and the high winds, but what about Lake Ontario flooding in 2017 and 2019? These were two events where water levels were more than two feet higher compared then where the level is today. We know that thousands of folks right along the shoreline of Lake Ontario were dealing with significant flooding. This is the kind of flooding that actually changed the shoreline of Lake Ontario.

If you look at it look at this in terms of the national survey, 63% of the victims of extreme weather across the county stated that they were now more likely to worry about climate change. That is according to Gallup Poll.

The history of the Mount Morris Dam and Hurricane Agnes

By Stacey Pensgen

Rochester sits nestled along the Genesee River, which makes the Flower City picturesque, but also prone to frequent floods. That is, until the Mount Morris Dam was completed 70 years ago this summer. The massive dam in Letchworth State Park stretches 1,028 feet across and rises 245 feet up from the valley floor. It had never been pushed to the limit until the remnants of Hurricane Agnes swept through the Southern Tier 20 years after completion of the dam.

Steve Winslow, Manager of the Mount Morris Dam, describes what happened.

"All of a sudden, it just starts dumping torrential amounts of rain, and the first thing it did was take out the gauge stations in Scio and Wellsville upstream of the dams," Winslow said. "So now the operators here don’t know what’s coming."

What is normally just a muddy river bed upstream of the dam, turned into a torrent.

The water behind the dam built up so quickly, that within a matter of three days, it went from virtually nothing to the water almost spilling over the top. There was a lot of debris in that, as well. So in order to alleviate the worst of the flooding, dam managers opened up the conduits below the dam in order to allow the debris-free water to flow through a little quicker, and while there was some flooding downstream, the worst of it was prevented.

"If we hadn’t held back that additional water, this 302,000 acre feet of water that was stored behind the dam, that would have caused catastrophic flooding," Winslow said. "City streets flooded, infrastructure just completely inundated."

Even so, downstream communities sustained $2.9 million worth of flood damage.

"To put it in perspective – was the dam useful during that event? Yeah, it prevented another 205 million dollars in damages and helped save lives, livelihood and structures, as well," Winslow explained.

In its 70 years the Mount Morris Dam has prevented an estimated $3.9 billion worth of flood damage. And it is constantly being maintained, and inspected daily, to make sure it is ready when it needs to be, just like it was in 1972.

After a hiatus during COVID, the Mount Morris Dam is now fully open for visitors to tour the dam once again.