Your Storm Forecast Is Going to Get More Precise

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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.

What Is a Bomb Cyclone?

Maddie Meyer/Getty Images
Maddie Meyer/Getty Images

The phrase bomb cyclone has re-entered the news this week as parts of the central U.S. face severe weather. Mountain and Midwestern states, including Colorado, Nebraska, Wyoming, and South Dakota, all fall in the path of a winter storm expected to deliver tornadoes, hail, heavy snow, flooding, and hurricane-force winds on Wednesday, March 13 into Thursday. It seems appropriate for a storm that strong to have bomb in its name, but the word actually refers to a meteorological phenomenon and not the cyclone's explosive intensity.

According to The Denver Post, the bomb in bomb cyclone stands for bombogenesis. Bombogenesis occurs when a non-tropical storm experiences at least a 24 millibar (the unit used to measure barometric pressure) drop within 24 hours. Low pressure makes for intense storms, so a bomb cyclone is a system that's built up a significant amount strength in a short length of time.

This type of storm usually depends on the ocean or another large body of water for its power. During the winter, the relatively warm air coming off the ocean and the cold air above land can collide to create a sharp drop in atmospheric pressure. Also known as a winter hurricane, this effect has produced some of the worst snowstorms to ever hit the U.S.

The fact that this latest bomb cyclone has formed nowhere near the coast makes it even more remarkable. Rather, a warm, subtropical air mass and a cold, Arctic air mass crossed paths, creating the perfect conditions for a rare bombogenesis over the Rockies and Great Plains states.

Central U.S. residents in the bomb cyclone's path have taken great precautions ahead of the storm. Over 1000 flights have been canceled for Wednesday and schools throughout Colorado have closed.

[h/t The Denver Post]

Watch a Rare ‘Ice Tsunami’ Slam Lake Erie

Clean Lakes Alliance, Flickr // CC BY 2.0
Clean Lakes Alliance, Flickr // CC BY 2.0

A combination of freezing cold temperatures and high winds is creating an unusual phenomenon along Lake Erie. As KDKA reports, ice tsunamis are toppling onto lake shores, and many locals have been asked to stay inside and even evacuate their homes.

On February 24, 2019, the National Weather Service in Buffalo, New York issued a warning about dangerous wind gusts in the Lake Erie area. The service urged citizens to seek shelter indoors and avoid traveling if possible. Winds peaked at 74 mph earlier this week, the level of a Category 1 hurricane, and tore down trees and power lines throughout the region.

People who got close to Lake Erie during the windstorm witnessed a rare event known as an ice tsunami. When wind pushed ice on the lake's surface toward the retaining wall, the sheet broke apart and dumped massive ice chunks on the shore. The video below captures the phenomenon.

In some areas, the ice piles grew so large that roadways had to be closed. Residents of Hamburg, New York's Hoover Beach area were asked to voluntarily evacuate due to the encroaching ice.

Ice tsunamis, or ice shoves, are rare, but in some cases they can be life-threatening. In 2013, waves of ice shards from a Minnesota lake destroyed people's homes.

[h/t KDKA]

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