Despite the common perception of the wayward weatherperson, meteorology has evolved into a robust scientific discipline. For a system as large as Earth or a continent, the prognosticative abilities of the forecaster have become impressively accurate.
Still, we love to kvetch about a misinterpretation of the sky’s tea leaves, perhaps because we’re actually used to precise predictions. When an anticipated weather event does not transpire, we might file it away to become part of an availability heuristic, a cognitive bias in which we overestimate how often something happens because we can think of specific examples of that thing happening.
We should cut the weather people some slack.
The preceding screed does not mean they get it universally correct. In fact, the National Weather Service would be the first to tell you they have much to improve.
In 2014, the NWS began focus groups related to their advisory system. The result was clear: when it comes to weather warnings, the public is easily confused.
So, the service started a program called “Hazard Simplification.” Internally, they shortened it to the internet-ready “Haz Simp,” giving us an eye-catching title for today’s article. The goal of Haz Simp was simple: consolidate warnings to make it easy for people to prepare for inclement weather.
Haz Simp has slowly made progress through the years. In October 2024, NWS announced an overhaul of its winter advisory terminology.
In the past, missives about the cold might have included any or all of the following:
- Extreme Cold Watch
- Extreme Cold Warning
- Wind Chill Watch
- Wind Chill Warning
- Wind Chill Advisory
- Freeze Watch
- Freeze Warning
- Hard Freeze Watch
- Hard Freeze Warning
Examining the above issues on their own might not cause much confusion. An advisory is the lowest level of notice; something might occur. When an event is likely to develop, they issue a watch. And, if an event is about to happen or already chugging, we get a warning. If you just received one of the above notices, you’d likely realize it was going to be cold. What if you got a Wind Chill Warning, a Freeze Warning, and a Hard Freeze Watch, all at once? Obviously, it’s going to be nippy, but can you disambiguate the terminologies? How would seeing all three impact your decisions when it comes to the weather?
Outside of professionals and weather wonks, the focus groups divined that the specificity did not change how the general population prepared for bad weather.
So, the National Weather Service streamlined these cold advisories. Wind Chill now falls under Extreme Cold, while Freeze will cover Hard Freeze.
For the curious, a Freeze was defined as the temperature dropping below 32 degrees Fahrenheit, which could “result in significant damage to many unprotected plants, especially if the temperature remains at-or-below freezing for several hours.” Things had to be chillier for a Hard Freeze: under 28 degrees for at least one hour. A Hard Freeze was more likely to affect outdoor plumbing and to destroy plants. Makes sense, but how much difference would it cause in your preparations?
Wind Chill was always a tough sell to the public. It describes how a temperature feels when combining the actual mercury reading and wind speed. Obviously, the harder the wind, the colder it feels. Temperature can remain constant and the Wind Chill can decrease as air speed increases. Again, does it change how one approaches cold?
The public said, “No!”
Will anyone miss the old terminology?
Haz Simp has already impacted other weather realms and, likely, most people don’t notice much. In 2017, the NWS nixed a stratification of Lake Effect Snow, Winter Weather, and Freezing Rain, opting to put them all under Winter Weather Advisory. Blizzard Watch and Lake Effect Snow Watch joined the Winter Storm Watch squad, too. Rounds of changes occurred in 2019 and 2021, regarding marine weather and flooding. Gone are the days of separating regular floods from flash floods!
For the record, the difference between a flash flood and a regular flood is one of duration and form. Floods can last for days or weeks, covering wide swaths; flash floods happen within hours of rainfall, can appear as raging torrents, and then disappear.
These simplification measures will likely allow forecasters to show severe weather more clearly on maps. When seconds matter, keeping things straightforward can save lives.
We will miss Wind Chill, though.
Further Reading and Exploration
Hazard Simplification – National Weather Service
Cold Criteria & Frost/Freeze Changes in Effect October 1, 2024 – National Weather Service
What Does NWS Consolidation Mean For the Extreme Cold, Freeze, and Wind Chill Product Suites? – NOAA
Freeze Definitions – National Weather Service
Wind Chill – National Weather Service
Flood and flash flood definitions – National Weather Service