Your Storm Forecast Is Going to Get More Precise

iStock
iStock

Just about every alert you hear before a storm creeps up on the horizon was issued by the National Weather Service (NWS). We use this federal agency's services almost every day without thinking about it. Daily forecasts, storm alerts, weather radars, and satellite images are all produced by thousands of meteorologists who work day and night to keep us safe. One part of keeping us safe is making sure we understand what they're trying to tell us. After all, what good is a warning if you don't know exactly what they're trying to say? The NWS is working to simplify the warning process to give us better information and help us make better decisions to stay safe during hazardous weather.

Right now, the NWS issues dozens of different alerts that cover all sorts of dangerous conditions. These alerts are called watches, advisories, and warnings, with each respective category carrying a greater sense of urgency. There are alerts for tornadoes, severe thunderstorms, floods, hurricanes, winter storms, and even conditions like dense fog or blowing dust.

The sheer number of alerts can be daunting, not to mention the sometimes-convoluted language forecasters use to tell us what's going on. It's easy to miss the distinction between a tornado watch and a tornado warning, for example. The Hazards Simplification Project is an ongoing effort within the National Weather Service to whittle down the number of alerts and use clearer language to give us a leg-up on dangerous weather conditions.

The first couple of changes will go into effect later in 2017. The NWS currently issues 10 different alerts for winter weather events such as blizzards, ice storms, lake effect snow, and snowstorms. In the winter, the agency will reduce the number of alerts to just six. They're getting rid of the blizzard watch, for example, merging it with the winter storm watch. Winter weather alerts will also be issued in a “what/where/when” format, outlining exactly how much snow or ice you can expect, where it's expected, and when it's expected to happen. Previously, you had to scour a few paragraphs of text to figure out what was coming your way.

The NWS will also look into changing their weather maps to display just four different colors when weather alerts are in effect—a dramatic change from the hodgepodge of colors that smear weather maps today. Each weather alert currently has its own unique color on weather maps, so these maps are almost indecipherable when there's a lot of active weather across the country. The agency may soon replace all of these colors with just four hues—yellow, orange, red, and purple—to convey the severity and urgency of the alert in effect.

improved hazardous weather map from the NOAA
A swath showing the probability of a tornado near Birmingham, Alabama, under the new FACETs project. The old tornado warning polygon is outlined in red.
NOAA/NSSL

There are also some big changes in the works for warnings in the future. Meteorologists used to issue tornado and severe thunderstorm warnings for entire counties, which didn't work out too well as some counties in the United States are enormous compared to the size of a single thunderstorm. About a decade ago, they reduced these warnings to polygons that covered just the area expected to be impacted by the storm. This greatly reduced false alarms and helped warn only the people who needed to take shelter.

In the next couple of years, the NWS will roll out a project called Forecasting a Continuum of Environmental Threats (FACETs). This project will reduce those old warning polygons even further into a swath that shows the probability that a certain area will be affected by a tornado, large hail, or damaging winds. The resulting warning area, seen above, looks similar to the cone of uncertainty forecasters use ahead of hurricanes and covers a much smaller area than the old polygons. This will allow forecasters to warn only those directly affected by the approaching hazards, reducing false-alarm rates even further and giving people greater confidence that they should take action right away instead of waiting it out.

Storm Leaves Homes Along Lake Erie Covered in Up To Three Feet of Ice

Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
John Normile/Getty Images

This past weekend, lakeside residents of Hamburg, New York, awoke to find their neighborhood transformed into a full-scale replica of Frozen’s ice-covered kingdom, Arendelle.

According to CNN, gale force winds produced giant waves that sprayed the houses along Lake Erie with sheets of water for two days straight, covering them in layers of ice up to three feet thick.

“It looks fake, it looks surreal,” Hamburg resident Ed Mis told CNN. “It’s dark on the inside of my house. It can be a little eerie, a little frightening.”

While the homeowners are anxious for the ice to melt, they’re also concerned about what could happen when it does.

“We’re worried about the integrity, of structure failure when it starts to melt, because of the weight on the roof,” Mis said.

He added that this is the worst ice coating he’s seen since he moved to the area eight years ago—but it’s not because they’ve had a particularly harsh winter. In fact, just the opposite is true. According to The Detroit News, warm winter temperatures have caused ice cover on the Great Lakes to drop from 67 percent in 2019 to less than 20 percent this year.

“Lake Erie typically has significant ice cover by this time of the year, and that protects the shoreline from these battering storms,” The Weather Channel’s winter weather expert Tom Niziol explained in a video.

The phenomenon has created another unforeseen issue for Hamburg’s coast, too: Tourism. The local police department posted a message on Facebook on Sunday, March 1, asking people to keep off both the “extremely unsafe and unstable” ice and people's private property.

[h/t CNN]

What is Lake-Effect Snow?

Tainar/iStock via Getty Images
Tainar/iStock via Getty Images

As you probably guessed, you need a lake to experience lake-effect snow. The primary factor in creating lake-effect snow is a temperature difference between the lake and the air above it. Because water has a high specific heat, it warms and cools much more slowly than the air around it. All summer, the sun heats the lake, which stays warm deep into autumn. When air temperatures dip, we get the necessary temperature difference for lake-effect snow.

As the cool air passes over the lake, moisture from the water evaporates and the air directly above the surface heats up. This warm, wet air rises and condenses, quickly forming heavy clouds. The rate of change in temperature as you move up through the air is known as the "lapse rate"; the greater the lapse rate, the more unstable a system is—and the more prone it is to create weather events.

Encountering the shore only exacerbates the situation. Increased friction causes the wind to slow down and clouds to "pile up" while hills and variable topography push air up even more dramatically, causing more cooling and more condensation.

The other major factors that determine the particulars of a lake-effect snowstorm are the orientation of the wind and the specific lake. Winds blowing along the length of a lake create greater "fetch," the area of water over which the wind blows, and thus more extreme storms like the one currently pummeling the Buffalo area. The constraints of the lake itself create stark boundaries between heavy snow and just a few flurries and literal walls of snow that advance onto the shore. The southern and eastern shores of the Great Lakes are considered "snow belts" because, with winds prevailing from the northwest, these areas tend to get hit the hardest.

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